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Gable Venting, Building “Installation” Included, and a “Livable” Barndo?

This week readers “ask the Guru” about how to best vent gable ends of a structure with no overhangs, if Hansen includes “installation” with purchase of a kit, and Mike asks if these barndos are “livable.”

DEAR POLE BARN GURU: I am working on a 30’x40′ pole barn that has no eave overhang/vented soffit. I am planning to renovate the barn for a customer of mine and want to make sure I order/install the correct gable end venting. Please let me know if you have any information regarding the project to make sure I best serve my customer! Let me know if you need any more information regarding the barn. Thank you! PEYTON in TRAVERSE CITY

DEAR PEYTON:

• R806.2 Minimum Vent Area. The minimum net free ventilating area shall be 1/150 of the area of the vented space. Exception: The minimum net free ventilating area shall be 1/300 of the vented space provided one or more of the following conditions are met:

1. In climate zones 6, 7 and 8, a Class 1 or 2 vapor retarder is installed on the warm-in-winter side of the ceiling.

2. At least 40 percent and not more than 50 percent of the required ventilating area is provided by the ventilators located in the upper portion of the attic or rafter space. Upper ventilators shall be located no more than 3 feet below the ridge or highest point of the space, measured vertically, with the balance of the required ventilation provided by the eave or cornice vents. Where the location of wall or roof framing members conflicts with the installation of upper ventilators, installation more than 3 feet below the ridge or highest point of the space shall be permitted.

• R806.3 Vent and Insulation Clearance. Where eave or cornice vents are installed, insulation shall not block the free flow of air. A minimum of a 1 inch space shall be provided between the insulation and the roof sheathing and at the location of the vent.

With 1200 square feet, if you vent ridge with at least 231 square inches of NFVA, but no more than 288 square inches, you can use gable vents to provide an air intake so total gable and ridge NFVA is 576 square inches (these values being bare minimums). Beware of gable vents as their actual physical dimensions are far greater than their NFVA.

 

DEAR POLE BARN GURU: Is installation included in kits? NICOLE in BRIGHTON

Hansen Buildings Construction ManualDEAR NICOLE: Hansen Pole Buildings is America’s leader in providing fully engineered, 100% custom designed, post frame building and barndominium kits, with multiple buildings in all 50 states. Your new building kit is designed for the average physically capable person, who can and will read and follow instructions, to successfully construct your own beautiful building shell (and most of our clients do DIY – saving tens of thousands of dollars – need a builder, we can probably help you there too https://www.hansenpolebuildings.com/builder-terms-conditions/). We’ve had clients ranging from septuagenarians to fathers bonding with their teenage daughters erect their own buildings, so chances are – you can as well! Your new building investment includes full multi-page 24” x 36” structural blueprints detailing the location and attachment of every piece (as well as suitable for obtaining Building Permits), the industry’s best, fully illustrated, step-by-step installation manual, and unlimited technical support from people who have actually built post frame buildings. Even better – it includes our industry leading Limited Lifetime Structural warranty! We would appreciate the opportunity to participate in your new pole building. Please email your building specifics, site address and best contact number to our Design Studio Manager Caleb@HansenPoleBuildings.com 1.866.200.9657 Thank you.

 

DEAR POLE BARN GURU: Are these barndos livable? MIKE in BETTENDORF

DEAR MIKE: Absolutely they are! I built my first one in 1990 as a combination ADU/Garage/Office and it has been in use continually now for 36 years! My most current personal one was built nearly 20 years ago, has 8000 finished square feet on two levels plus a mezzanine (it includes a basketball half-court and two elevators). Tens of thousands of barndominiums are now being built every year in America. We have provided them to clients in nearly every state.

This entry was posted in Building Styles and Designs, Barndominium, Constructing a Pole Building, Pole Barn Planning, Shouse, floorplans, Alternate Siding, Building Interior, Budget, Lumber, Pole Barn Questions, Pole Barn Homes, Pole Barn Design and tagged , , , , , , , , on by .

I Didn’t Plan on How to Ventilate My Pole Barn Attic

I Didn’t Plan on How to Ventilate My Pole Barn Attic

Reader BRANDON in MILAN writes:

“I am looking to install a metal ceiling on my pole barn and insulate. It’s is a 30x40x12 building with metal roofing and siding, with a radiant vapor barrier around the entire building. No soffits or ridge vent. Hindsight I should have had that done at install. So I am looking at adding gable vents with one side being a powered fan. On the gable end over my garage doors I am struggling to figure out a way to install them around the framing. What would be the best way to go about this? Thanks.”

Whoever built this building did you no favors. In order to properly ventilate, your building should have gable vents (air intakes) and a ridge vent (air exhaust). Gable vents, on their own, make for a very poor ventilation system – they work well immediately inside endwalls, however move very little air in center of building. Remove ridge cap and any closure strips, cut away radiant barrier at center and cut upper inch of ridge purlin out on both sides of ridge. Apply vented closure strips on each side of ridge and reinstall ridge cap. Install vinyl gable vents with snap rings in each endwall. You need to have one square foot of NFVA (Net Free Ventilation Area) for each 150 square feet of attic floor. One important note – attic floor area is just as it reads – area – not volume. This is a minimum requirement and does not stipulate required ventilation openings provide intake (low), exhaust (high), or both.

You can provide one square foot of NFVA for each 300 square feet of attic floor if both following conditions are applicable:

A Class 1 (≤ 0.1 Perm) or 2 (> 0.1 to ≤ 1.0 Perm) vapor retarder is installed on warm-in-winter side of ceiling when structure is located in climate zone 6, 7, or 8 (you are not). At least 40%, but not more than 50% of NFVA is provided by vents located not more than 3 feet below roof’s highest point.

Provision for a minimum one-inch air space between roof sheathing and insulation in attic at vent location.

This entry was posted in Trusses, Ventilation, Building Interior, Barndominium, Insulation, Pole Barn Questions, Pole Barn Design, Roofing Materials and tagged , , , on by .

Venting an Attic Without Soffit Air Intake

Venting an Attic Without Soffit Air Intake

Loyal reader KEN has an attic space with only air exhaust points – a vented ridge, and no air intake. His dilemma, how to adequately ventilate his attic without vented soffits.

Ken writes:

“I finally was able to make contact with the manufacturer of the open foam like material used under my ridge as a vent. The following is cut and pasted from their technical material: Net Free Area 1”nom.Thickness 8.5 sq.in.per lin.Ft.per side (17 sq.in .per lin.Ft.ridge).  Since I have a 60 foot ridge, that would equal 1020 sq. in. or 7 sq. ft. 

Given the ridge vent, do you still recommend 3 sq. ft.  venting on each end?

You note that an 18×24 would provide 140 sq in (or 0.97 sq. in.), but 18×24 is 432 sq in.  Do the louvers and other components reduce that by a factor of 3, just wanting to confirm.  With a 3 sq. ft. requirement, I would need a vent nearly 3 times an 18×24.  Maybe it just comes down to not the ideal but what can be practically installed. 

In order to prevent rust at the cut line, should I caulk the outside seam where the louver comes through the wall?”

Mike the Pole Barn Guru writes:

Another way of thinking about ventilation – view it like a straw. Obviously with best (and most) straws each end has an opening. What happens when a hole exists somewhere between ends? A reduction occurs in your ability to draw up water or soda. A similar effect happens when different vent types are employed over a shared air space.

Air and water are similar, their flow follows a path of least resistance. In a properly designed and installed attic ventilation system air flow travels from intake vents to exhaust vents, flushing out warm, humid air along roof deck (think underside of roof steel). However, if two or more different types of exhaust vents (gable and ridge) are used above a shared attic air space, one exhaust vent will likely to interrupt air flow to the other. In this arrangement it becomes another intake vent for a primary exhaust vent – leaving large sections of attic space incorrectly vented.

I would be inclined to seal ridge vent off and utilize gable vents. Dimensions of gable vents are overall unit dimension, not net free area (reduced from overall size by both exterior framework and louvers). Each endwall may require multiple vents in order to achieve an adequate airflow.

Caulking cut edges of endwall steel would certainly not hurt. A suggested caulking would be TITEBOND Metal Roof Translucent Sealant.

 

 

 

This entry was posted in Pole Barn Structure, Ventilation, Pole Barn Questions, Pole Barn Design, Building Overhangs and tagged , , , on by .

Attic Ventilation – Where Hindsight is Always 20-20

Attic Ventilation – Where Hindsight is Always 20-20

Reader CHRIS in TULSA writes:

“Hello! I have a question about attic venting that I’m just not experienced enough to answer properly. I have a new 24’x’40’x12′ post frame building I’m currently working on finishing out (fiberglass insulation, walls, ceiling, etc.). My hindsight was bad and I didn’t opt for getting an overhanging roof with soffit venting, etc. Instead I did have the builder install 2, 10′ ridge vent sections on both ends of the roof. The building will not have plumbing, but will be air conditioned with mini splits, etc. My question to you is regarding properly venting the “attic” space created once the ceiling is installed. Again, I have 2, 10′ ridge vent sections as the exhaust, but was wondering if I need to add some gable venting or something similar as the intake. I should also add the entire barn has been wrapped in Tyvek. Any help with this is greatly appreciated, or if you sell a product that would help I would be interested in more information on it. Thank you for your time!”

Sadly builders and building providers rarely take proper ventilation into consideration, leading to me getting lots of questions asked about solving later challenges.

vented-closure-stripYour ridge vents will only “work” when you have properly sized and placed air intakes. In your case, you will be limited to gable end vents. Gable vents are not nearly as effective as eave/soffit vents, so you are likely to experience poor air flow as you approach center of your building (and could have some condensation issues there as well). Tyvek would not have been my first choice in your roof, as it allows moisture to pass out and become trapped between it and your roof steel. This could potentially cause some premature degradation, over time.

At least 40% and no more than 50% of your ventilation can be located in upper portion of your attic space. You will need to know NFVA (Net Free Ventilating Area) of your ridge vents, then NFVA of your gable vents should be equal to, or slightly greater than your exhaust. Gable vents should be placed as low as possible, to achieve best airflow.

This entry was posted in Building Interior, Insulation, Pole Barn Questions, Building Overhangs, Barndominium, Pole Building How To Guides, Pole Barn Planning, Pole Barn Structure, Trusses, Ventilation and tagged , , , , , on by .

A Radiant Barrier Issue, Venting in Humidity, and Frost Walls

This week the Pole Barn Guru answers reader questions about insulating a building that already has reflective foil radian barrier, if one needs vents or exhaust fan in the gable ends of the roof with the high heat/humidity of Alabama, and requirements for frost wall or slab for frost heave.

Reflective InsulationDEAR POLE BARN GURU: I recently moved into a house with a 40×30 pole barn (wood post and wood trusses) with a metal exterior. The building has a reflective foil radiant barrier between the metal and wood structure. It is extremely hot in the summer and cold in the winter. I want to insulate and cannot afford spray foam. I also don’t have the ability to remove the walls to remove the foil barrier that way. I do have some Silvercote insulation that has an attached vapor barrier. It is just a fiberglass roll insulation that has an attached vapor barrier to it. It is sold around here for use as insulation in metal buildings. I was given enough to insulate the whole shop from someone that had left overs. I would like to install this insulation to help with temps in the shop. I have tried to research to get an answer on the best way to go about this. The shop builder said just put it up but I feel that would create a double vapor barrier. Is my best route to cut the foil radiant barrier out and then install the fiberglass insulation with vapor barrier facing the interior of the building? This would basically take the foil barrier out and install the fiberglass against the metal with the attached face vapor barrier to the inside of the building. I want to make sure I do it right. Thank you. DAVID in OKLAHOMA CITY

DEAR DAVID: If you are dead set on using this Silvercote insulation then you should cut out any foil radiant barrier. You never want to have a double vapor barrier situation as any trapped moisture will have no method of escaping. Downside of this is you do not have a Weather Resistant Barrier (aka housewrap) between framing and siding. An option to consider would be to resell your metal building insulation, then use unfaced Rockwool batt insulation, as it is unaffected by moisture.

 

DEAR POLE BARN GURU: I plan to build a 28×48 metal pole barn, concrete floor, 12′ eave with 8/12 pitch. Barn will have 6 3×4 windows, and two 10×10 roll doors, one roll door on each gable end. For now, the roof will be insulated with 3in closed cell foam. I plan to insulate the walls down the road with rigid foam board. The building will not have A/C. Question: Do I need vents or exhaust fan in the gable ends of the roof with the high heat/humidity of Alabama? There will be no ridge vent or soffit vents. I may not have the building open every day, either. Thank you. JASON in MONTGOMERY

DEAR JASON: While placing permanent vents might alleviate your possible mold/mildew/condensation issues, they will defeat your insulation investment. In reality, you should look to a qualified local HVAC provider to provide mechanical dehumidification, else you will have regrets forever. Make sure to have a vapor barrier under your concrete floor, to help reduce interior moisture gain.

 

DEAR POLE BARN GURU: FROST HEAVE, 44′ deep by 64 long pole barn 20 ceiling height, Tenant build, will be insulated but NO HVAC initially. However, is some type of concrete frost wall (downturn?) via monolithic slab required? Dimensions? MIKE in CINCINNATI

DEAR MIKE: Your slab on grade can be poured to a consistent thickness throughout and all you need to do is properly insulate your slab edge to meet IECC (International Energy Conservation Code) requirements.

This entry was posted in Building Interior, Budget, Pole Barn Homes, Insulation, Pole Barn Questions, Pole Barn Planning, Pole Barn Heating, Barndominium and tagged , , , , , , , , , , on by .

Attic Ventilation – Where Hindsight is Always 20-20

Attic Ventilation – Where Hindsight is Always 20-20

Reader CHRIS in TULSA writes:

“Hello! I have a question about attic venting that I’m just not experienced enough to answer properly. I have a new 24’x’40’x12′ post frame building I’m currently working on finishing out (fiberglass insulation, walls, ceiling, etc.). My hindsight was bad and I didn’t opt for getting an overhanging roof with soffit venting, etc. Instead I did have the builder install 2, 10′ ridge vent sections on both ends of the roof. The building will not have plumbing, but will be air conditioned with mini splits, etc. My question to you is regarding properly venting the “attic” space created once the ceiling is installed. Again, I have 2, 10′ ridge vent sections as the exhaust, but was wondering if I need to add some gable venting or something similar as the intake. I should also add the entire barn has been wrapped in Tyvek. Any help with this is greatly appreciated, or if you sell a product that would help I would be interested in more information on it. Thank you for your time!”

Sadly builders and building providers rarely take proper ventilation into consideration, leading to me getting lots of questions asked about solving later challenges.

vented-closure-stripYour ridge vents will only “work” when you have properly sized and placed air intakes. In your case, you will be limited to gable end vents. Gable vents are not nearly as effective as eave/soffit vents, so you are likely to experience poor air flow as you approach center of your building (and could have some condensation issues there as well). Tyvek would not have been my first choice in your roof, as it allows moisture to pass out and become trapped between it and your roof steel. This could potentially cause some premature degradation, over time.

At least 40% and no more than 50% of your ventilation can be located in upper portion of your attic space. You will need to know NFVA (Net Free Ventilating Area) of your ridge vents, then NFVA of your gable vents should be equal to, or slightly greater than your exhaust. Gable vents should be placed as low as possible, to achieve best airflow.

This entry was posted in Insulation, Pole Barn Questions, Building Overhangs, Barndominium, Pole Building How To Guides, Pole Barn Planning, Pole Barn Structure, Trusses, Ventilation, Building Interior and tagged , , , , , on by .

Challenges to Insulating an Existing Pole Building

Challenges to Insulating an Existing Pole Building

Reader TODD in STACY writes:

“Hello, I am looking to insulate and heat an existing 30x40x12 pole building that was built in the mid 2000’s. It does not have soffits or ridge vents. The way it is now it gets condensation on the inside quite often just with daily weather, I assume because of the lack of ventilation. I am planning on steel liner panel ceiling, poly vaper barrier and blown in fiberglass. But the problem is how do I achieve adequate ventilation without soffits? I am worried that once i get all the insulation in and still have condensation problems and end up with wet insulation. Also, last spring, as ALL the snow from last winter was melting the water was making it up and under the roof overlaps and was freezing and spreading them open and dripping inside! Would having it insulated have kept this from happening? I couldn’t help but think it was a good thing I didn’t have it insulated then or my insulation would of been soaked! But I thought maybe it wouldn’t of happened if it had been insulated, what are your thoughts on that? When it comes the wall insulation some say to wrap everything with a house wrap from the inside, insulate with fiberglass and then poly vaper barrier and then the steel liner panel. Others say the house wrap isn’t necessary just the inside poly. What do you recommend? Thank you for your help!”

It sounds like your building has several things going on, some of them easily fixable.

If your building does not have an under-slab vapor barrier – seal it. This is your top source of moisture inside of buildings. Think of concrete as a sponge rather than a solid (concrete being actually relatively porous). Pores in concrete (smaller than human hairs. so invisible to a naked eye) constitute 12 to 18% or more of a concrete slab!

Water coming through roof steel laps…this will normally only occur if steel has been overlapped incorrectly. Smaller, or partial, rib should go over top of larger full rib. This occurs all too often, even when supposedly professional builders are hired. If this is your case, it can be remedied – remove ridge caps (number them, so they get put back in same order they came off), then remove screws closest to laps. Pull up on edge of panel currently on top. While it is being held up, pull up on other panel edge, then put full lap edge down, overlapping it with partial lap. Use screws one size large diameter and 1/2″ greater in length to refasten steel panels.

vented-closure-stripWhile ridge cap is off, replace solid foam closure strips with vented ones. Use 1-1/4″ long #12 stitch (metal-to-metal) screws to reattach ridge caps.

Add gable vents for air intake, bottom edge of vents should be just above thickness of ceiling insulation you will be adding. You will need to add 144 square inches of NFVA (Net Free Ventilating Area) at each end.

I am guessing your roof steel has no means of controlling condensation currently. Your easiest solve, at this point, is to have two inches of closed cell spray foam applied directly to underside of roof steel. Otherwise, you could remove entire roof and install a thermal break. Some possibilities would be reflective radiant barrier (with seams taped), metal building insulation (with seams overlapped and stapled together), or solid sheathing (such as plywood or OSB) with 30# felt applied over top.

If you can obtain it, consider blowing in granulated rockwool, rather than fiberglass, as it is not affected by moisture.

Walls – while housewrap would have been nice, rather than pulling off all wall steel, I would use rockwool batts to entirely fill cavity, well-sealed interior vapor barrier, then your steel liner panels.

This entry was posted in Ventilation, Building Interior, Insulation, Pole Barn Heating, Pole Barn Questions, Barndominium, Roofing Materials, Pole Building How To Guides and tagged , , , , , , , on by .

Attic Ventilation, Shearwall Stitch Screws, and Adding Sheathing

This week the Pole Barn Guru addresses reader questions about ventilation needed for a new attic with metal ceiling and blown-in insulation, a confirmation for endwall needing stitch screws for shear, and if adding sheathing to an existing pole building would add value.

DEAR POLE BARN GURU: I bought a house with a pole barn that is unfinished inside. The metal walls were not wrapped and the only insulation in the barn whatsoever is double bubble on the underside of the barn roof. I am going to have a metal ceiling put in and then blown fiberglass insulation for an R30 value in what will then be the attic. There is currently no ridge vent nor gable vents either so I am concerned about air flow in the attic once the metal ceiling and blown insulation are complete. The eaves have perforated soffit so I’m hoping even after the blown insulation is done that will provide an air flow into the attic. So am I correct to think that I need to have gable vents put at each end or a ridge vent so that there is positive air flow through the attic? Thanks! BILL in STEVENSVILLE

DEAR BILL: Your thinking is absolutely correct – you need an adequate ventilation exhaust point. Ideally, this would be at your ridge. Gable vents, while meeting code requirements, actually only provide good ventilation immediately closest to vent locations.

This article covers requirements for attic ventilation: https://www.hansenpolebuildings.com/2023/06/274512/

In Queen Anne’s County – you are in Climate Zone 4A. 2021’s IECC (International Energy Conservation Code) specifies R-60 for ceilings in your climate zone. As so much of your cost of blown insulation is having installers show up, you may want to consider going with a greater R value than originally planned. Energy costs are not ever going to go down (nor cost of insulating).

 

DEAR POLE BARN GURU: I have a rear end wall that is labeled shear wall that says I need an inch and a quarter number 12. Stitch screw 9 and 3/8 on center. Is that every 9 and 3/8 on center vertically on each overlap? DAMINA in TONOPAH

DEAR DAMIAN: You are correct. Panels stitched together have roughly twice as much shear capacity as do unstitched panels.

 

DEAR POLE BARN GURU: Question for you Guru! I bought a property with a small pole building/shed. Is there any value in adding sheathing? If so, how do you retroactively figure out if the roof will handle the additional load? JESSE

DEAR JESSE: If the roof steel is properly fastened (1-1/2″ screws in flats along one side of each high rib in field, #12 or #14 x 1-1/2″ screws both sides of each high rib at eave and ridge) chances are it will perform admirably without any sheathing. Think of steel roofing and siding as acting like very strong, very thin OSB or plywood.

 

This entry was posted in Pole Barn Planning, Pole Barn Heating, Pole Building Siding, Barndominium, Ventilation, Uncategorized, Insulation, Building Interior, Pole Barn Questions, Pole Barn Design, Roofing Materials, Constructing a Pole Building, Fasteners and tagged , , , , , , , , on by .

What Size Fresh Air Intakes Do I Need?

What Size Fresh Air Intakes Do I Need?

Reader BOB in GRAHAM writes: “I have a 40 x 60 pole building. There is a ridge vent along the 60′. I recently installed Sheetrock on the ceiling and blew in insulation. My question is what size fresh air intake vents do they need to keep the attic cooler. I was thinking I need Air vents on each side of the end wall at the lowest points. The other thing is I can only pull fresh air in at one end of the building. As the other end is open to the ridge vent, separate from the other 60′. Should I put an electric intake fan rather than just an air vent?”

Here are ventilation requirements:

Provision of 1 square foot of NFVA (Net Free Ventilation Area) for each 150 square feet of attic floor. One important note – attic floor area is just as it reads – area – not volume. This is a minimum requirement and does not stipulate required ventilation openings provide intake (low), exhaust (high), or both.

Provision of 1 square foot of NFVA for each 300 square feet of attic floor if both following conditions are applicable:

At least 40%, but not more than 50% of NFVA is provided by vents located not more than 3 feet below roof’s highest point.

Provision for a minimum 1 inch air space between roof sheathing and insulation in attic at vent location.

Your 40 x 60 building would therefore require at least eight square feet ( 40 x 60 = 2400 / 300 ) or 1152 square inches of NFVA, with at least 50% of this been at eaves (vented sidewall soffits) or gable vents located in lower half of attic space.

While an electric powered fan would move air within your attic area, you do need to provide adequate intake area. 576 square inches of NFVA is a lot of gable vent (assuming you have no soffit intake vents).

This entry was posted in Insulation, Pole Barn Questions, Roofing Materials, Constructing a Pole Building, Ventilation, Building Interior, Pole Barn Heating and tagged , , , , , , on by .

Polyiso Pole Barn Ceiling Insulation

Polyiso Pole Barn Ceiling Insulation

Reader MIKE in OXFORD writes:

“I’ve moved into a house that also has an existing 30’x40′ (uninsulated) pole barn. I want to insulate and am considering 2″ thick polyiso foam boards attached to the bottom cord of the roof truss. The roof trusses are 4′ spacing. 1) Do you feel that is a good choice? 2) Do I need to add any type of vapor barrier (or anything else) above the polyiso boards?”

Before addressing your question, some concerns:

Does your building have some method for controlling condensation between roof framing and roof steel? This could be one of several options – well sealed reflective radiant barrier (bubble barrier) or metal building insulation, or solid sheathing (OSB or plywood) with either 30# felt or a synthetic underlayment. If not, two inches of closed cell spray foam should be applied directly to underside of roof steel. You really don’t want it ‘raining’ inside of your pole barn.

What sort of ventilation provisions are made for dead, non-conditioned attic space you are creating? Eave and ridge is best https://www.hansenpolebuildings.com/2018/03/adequate-eave-ridge-ventilation/. While Code requirements can be met with gable vents, they do not provide uniform air flow throughout area being vented.

Are trusses designed to support a ceiling load? Most widely spaced post frame trusses are designed with a minimal ceiling load – generally enough to cover weight of truss and small amounts of wiring and light fixtures. While polyiso is unlikely to create a weight overload, should you opt for other solutions, it could pose a challenge.

Some good things about polyiso insulation – at two inches thick, it only weighs 1/2 pound per square foot. Polyiso insulation delivers a high level of inherent fire resistance when compared to other foam plastic insulation due to its unique structure of strong isocyanurate chemical bonds. Polyiso has an R value of six per inch, however polyiso’s R value gets worse when it’s cold outside. Building Science Corporation’s published research shows polyiso can lose as much as 25% of its R-value when temperature drops (in general R value begins to decrease below 75 degrees Fahrenheit).

Now to address your questions:

1) If you can obtain polyiso at a reasonable price and are looking at only minimal heat retention, it might be a great solution. Personally, I would add a ceiling (steel liner panels are relatively affordable and light weight) and blow in rockwool, provided trusses are adequately designed to support added imposed weight. Adequate ventilation and a condensation control system would be a must for either.

2) A ceiling vapor barrier is only needed if your site has over 8000 heating degree days per year (only found in far northern extremes in our country). Please keep in mind, in order to function well you are not going to be able to have unsealed penetrations for wiring or light fixtures.

This entry was posted in Pole Barn Questions, About The Pole Barn Guru, Pole Barn Planning, Trusses, Ventilation, Insulation and tagged , , , , , , on by .

Things My Pole Builder Didn’t Discuss With Me

Things My Pole Barn Builder Didn’t Discuss With Me

Somehow I feel as if this should be a Jeopardy question for $400…..

Reader MATT in BUFFALO writes:

“Hi there, my pole barn has recently been constructed and I’m now looking forward to insulating and finishing the inside. My hope is to drywall all interior surfaces including the ceiling. I realized as we were finishing the build that this was never really a discussion with our builder, specifically for the ceiling. I would like to add 2×4 or 2×6 ceiling joists 24″ on center and hang 5/8″ drywall for my ceiling finish and insulate somewhere in the r38 range with fiberglass. I do not intend on having any storage above the bottom chord, but will leave access to the space. My truss plans show a bottom chord dead load of 5.0 psf and states in the notes that the truss has been designed for a 10 psf bottom chord live load, although under loading it shows a bcll of 0.0. It also mentions for bottom chord bracing that a ‘rigid ceiling directly applied or 5-8-15 oc bracing’ is allowed. I think 5.0 psf leaves me just barely enough to finish this how I’d like, but I’d like to run it past someone with experience. I’ve unfortunately had the hardest time getting a hold of the truss designer/manufacturer. Thanks!!”

Mike the Pole Barn Guru writes:

Oh – things somehow never being discussed before a build gets started…..

Don’t get me wrong, I am not blaming you.

Any responsible builder or building provider should thoroughly know their client’s eventual end use for their building and offer some reasonable options to achieve those goals. Sadly – so many “professionals” know only how to sell on a cheap price rather than value added benefits to potential building owners.

Let’s run through possible challenges –

Condensation control. Unless some provision was made to keep warm moist air from rising and touching underside of roof steel, it will “rain” in your attic. Solutions at time of construction (in order of preference) would be: a factory applied integral condensation control (https://www.hansenpolebuildings.com/2020/09/integral-condensation-control-2/), a well-sealed reflective radiant barrier (it really isn’t insulation https://www.hansenpolebuildings.com/2014/04/reflective-insulation-wars/), installing over solid sheathing (OSB or plywood) with 30# felt or a synthetic underlayment, or Metal Building Insulation (https://www.hansenpolebuildings.com/2011/11/metal-building-insulation/).

If no provision has been made, your option now would be two inches of closed cell spray foam applied directly to the underside of roof steel.

Ventilation. When creating a non-conditioned attic space, it must be adequately vented. Gable vents can be Building Code conforming, however from a practicality standpoint, they only ventilate well closest to their location (building ends). Best design solution is intakes at eaves, exhaust through ridge. Here are your requirements: https://www.hansenpolebuildings.com/2018/03/adequate-eave-ridge-ventilation/.

Most pole barn trusses are designed for a one psf (pounds per square foot) bottom chord dead load (BDCL) – inadequate for any type of ceiling. On truss spans of up to and including 40 feet, we include a five psf BCDL as a matter of practice (too many clients decide later on they want a ceiling) and if we know in advance a ceiling is to be installed, we use 10 psf BCDL. You have been fortunate to have at least a five psf BCDL. Your 10 psf bottom chord live load is a non-concurrent (assumes no other live loads are being applied such as snow) one and basically is there to provide a minimum degree of structural integrity allowing for occasional access to an attic space for maintenance purposes.

Depending upon span between trusses, size and grade of ceiling joists can be looked up at chapter-8-roof-ceiling-construction scroll down to Table R802.5.1(1). In order to support 5/8″ sheetrock, ceiling joists should be spaced no greater than 24 inches on center.

Your actual dead loads will be roughly 1 psf for truss bottom chord itself (includes minimal wiring, lighting and truss bracing), 2×6 ceiling joists 24″ o.c. (I use one psf although actual load is slightly lower https://www.hansenpolebuildings.com/2013/02/2×6-lumber/) and your blown fiberglass (about a pound per cubic foot), so you should be okay. Cellulose or rock wool insulation are about three times as heavy as fiberglass, pushing to BCDL capacity, although my recommendation would be rock wool over other products as it is unaffected by moisture (fiberglass with even 1.5% moisture content can lose roughly half of its R value).

This entry was posted in Ventilation, Insulation, Pole Barn Questions, Pole Barn Design, Pole Barn Planning, Pole Barn Structure, Trusses and tagged , , , , , , , , , on by .

Moisture Barrier for a North Idaho Hanger

Moisture Barrier for a North Idaho Hangar

Reader BILL in SANDPOINT writes:

“Hey guru! Question about insulation – moisture barrier. We are under construction on a 64×70 post frame aircraft hangar in North Idaho. The eave height is 19 feet, plus a two foot heel. There are no overhangs. Roof pitch is 3:12 and the ceiling is vaulted 1:12 there will be a 58 foot wide by 18 foot tall hanger door. Attic venting will be from gable end vents. The roof will be sheathed with 7/16 OSB and receive 30# felt under the 26 gauge PBR. The walls will be sheathed 7/16 OSB and house wrapped under the 29 gauge steel panels. The plan is to install metal liner panel on the ceiling and 5/8″ drywall on the walls. Insulation will be r49 blow in the attic, and r25 unfaced batts in the walls. The hanger door is yet to be determined, but it might also be unfaced batts under a metal liner. Two 125,000 BTU radiant tube heaters will be installed in the ceiling. They will be vented outside and will draw combustion air from outside. I am thinking that it makes sense to install a full vapor barrier for the walls and the ceiling, but would appreciate your thoughts on the matter.”

 Mike the Pole Barn Guru writes:

Before we get to your question, I have some concerns….

First – you are putting a 58 foot wide door in a 64 foot endwall. This leaves only three feet of solid wall on each side of your door opening. These areas need to be shearwalls and maximum aspect ratio for a shearwall is 4:1 (four feet of height for every foot of width). With a three foot wide shearwall your maximum opening height would be 12 feet. You are likely to experience some tremendous racking problems (if not a failure) on your door endwall.

Second – trying to ventilate a 4480 square foot dead attic space with gable vents will require 1075.2 square inches of NFVA (Net Free Ventilating Area) in each endwall and this is providing half of NFVA is located in each upper and lower half of each endwall. You could accomplish this with say four 24″ x 36″ galvanized gable vents each end, however this might not be your most aesthetically pleasing design solution. Downside of gable vents is once you get past your first pair of trusses, airflow becomes negligible. I would be much happier with vents in your sidewalls (in area of truss heels) as an intake, combined with continuous ridge venting.

If it were me – I would use unfaced R-30 rockwool batts in sidewalls (they are not affected by moisture and R value does not degrade over time like fiberglass does) with a well-sealed interior vapor barrier before hanging drywall. This would allow your walls to dry to outside. Ceiling should not have a vapor barrier, as you want moist air to be able to escape into your well ventilated attic. I would blow in R-60 of rockwool.

Best of success with your build.

This entry was posted in Pole Barn Questions, Pole Barn Design, Pole Barn Planning, Trusses, Ventilation, Insulation and tagged , , , , , , , , on by .

Help! My Barndominium Roof is Dripping!

Help! My Barndominium Roof Is Dripping!

Reader TIMM in WHITEFISH writes:

“Thanks for taking my question. I recently built a barndominium in NW Montana. I tried to find someone to build it for me, but the demand and cost in the area had gone up so much that I had to do almost all the work on my own. I was not completely unfamiliar with building but not an expert by any means but I was able to get it built with helpful videos found online. I finished the home in late October and have moved in. The home is 28’x36′ with 10′ walls and is all living space, no garage. I had planned on doing spray foam insulation around the entire shell of the barn and had hired a company in August to come out and spray the barn but they were not going to be able to get to the building until December at the earliest but we were willing to do it and fight through the winter in our camper. Our plumber mentioned a product to us that he had seen some other clients use called Prodex that had similar characteristics of spray foam with a reflective surface on both sides and it was something I could do myself and much sooner. I did some research and the product looked good and the reviews looked good so I bought some and installed it. The steel was already on when I installed it so the Prodex was installed by stapling or screwing to the Purlins/Girts around the whole building which was an install method on their website. While we were mudding/painting/texturing I noticed some condensation in the attic in between the steel and the Prodex insulation (I could see where it was coming through a seam in the Prodex). I asked some people and they thought it was just because I was putting a lot of moisture in the air that was causing the condensation and it would dry out when we were done. On a recent trip up to the attic I noticed that the steel is still condensating when it is cold outside and the Prodex itself seems to be condensating as well. I emailed Prodex and they told me that it is caused by cold air moving across the inside surface of the steel and I should put foam around the ridge cap, eave edge of roof and tops of wall. I have foam around the ridge cap, but nothing on the ridge cap ends, I have foam on the eave edge of the roof, but only in the high ridge parts, and I have nothing on the walls. I am also concerned that this is happening inside of the walls which may lead to a bad mold problem next summer. My question is, how do I get it to stop condensating? I am ready to do whatever I need to do. I just don’t want to throw ideas at the house until something works. As far as ventilation goes, I am sure I do not have enough but was hoping to address that in the summer months. I do not have eaves on the building which I regret so my only real ventilation is the ridge cap and the little bit that may be coming through the ridges on the eave edge of the roof. I thought about gable vents, but I felt like that would let too much cold air in and would make the issue worse, but maybe that is what I need? If I put in gable vents, do I pull out the Prodex insulation and leave bare metal on the inside of the attic? I am trying to figure out a way to reduce the moisture right away (dehumidifier?) while I work on a long term solution but I don’t know which direction to go to solve this issue. I thought about pulling off the steel and putting in plywood sheeting, but we are in the middle of winter and that would have to wait until Spring at least and I am afraid I will end up with too much water damage by then. I have even considered putting sheeting under the roof and replacing the outside walls with wood siding but the cost would be high and I feel like there should be a solution to this issue. For heat we electric wall heaters (Cadet in-set wall units) occasionally and a pellet stove most of the time. We put the Prodex insulation as well as blown insulation in the attic to about 12 inches deep and we put Prodex as well as rolled insulation in the walls for a total of about an R30 value. Dryer and bathroom vents both go outside and nothing is venting into the attic. Any help would be appreciated! Thanks.”

Mike the Pole Barn Guru says:

Kudos to you for doing a D-I-Y. Sadly you were lead to a product (Prodex) claiming to be insulation, however in reality it is a condensation control, and only if totally sealed.

All of these issues could have been easily addressed at time of construction had your building kit provider given you proper advice.

First thing to do is to get your attic properly ventilated – you need to add at least 121 square inches of NFVA (Net Free Ventilating Area) to each gable end. This will give you an air intake and your vented ridge will then function as a proper exhaust. By itself, this should greatly minimize, if not totally cure your problems.

Pole Barn Guru BlogAs time allows, remove roof Prodex, have two inches of closed cell spray foam applied to roof steel underside, and increase thickness of blown in attic insulation to R-60.

If you do not have a well-sealed vapor barrier under your concrete floor, if possible, seal top side of it (this is where moisture is coming from).

Heating as much as possible with your pellet stove will also help to dry your interior air out and provided your slab is sealed, should help greatly.

I do have some concerns about your walls, if you have faced insulation batts with Prodex on outside of batts, you are potentially trapping moisture between two vapor barriers. If this is indeed your case, come Spring, remove siding (one wall at a time) , remove Prodex (as much as possible) and add a Weather Resistant Barrier (Tyvek or similar) to the exterior of framing, properly seal all wall openings and reinstall wall steel.

This entry was posted in Insulation, Pole Barn Heating, Pole Barn Questions, Roofing Materials, Barndominium, Ventilation and tagged , , , , , , , , , , , on by .

How Do I Ventilate My Barn’s Attic?

How Do I Ventilate My Barn’s Attic?

Right up there with curing condensation issues is how to properly ventilate a pole barn’s dead attic space.

Reader CURTIS in TRENTON writes:

“I have a 40’x60’ outbuilding that doesn’t have soffit vents for fresh air intake and the ridge cap has solid foam closures along the length of both sides of it so I have no air exhaust either. Basically just whatever air leaks are within the building. My plan is to fully finish the inside of my building. (Insulated walls and OSB sheathing and a metal ceiling with a blown in r-38) I plan on making it as air tight as possible. This building will be heated some over the winter as well. My roof panels also have the “drip X” felt like material that is attached to the underside of the panels. I believe this acts as a vapor barrier to keep the roof from condensing. My question is since I don’t have soffit vents or a vented ridge cap do you recommend adding 2 gable vents? If so, what size? I know there’s a formula for sizing them. I believe it is the square footage of the building, (40×60=2400/300=8 sq ft) so would be adding a 4 sq ft gable vent on each end of the building be sufficient? 4 sq ft of intake and 4 sq ft of exhaust totaling 8 sq ft of ventilation? Or should I do a gable vent on the west side of my building for air intake and a shutter exhaust fan wired to a humidistat/thermostat on the east side (away from prevailing winds) to pull hot air from the attic. I believe there’s a formula for this too to determine the fan’s cfm rating and the gable vent size. (40×60=2400×0.7=1680CFM) 

Add an additional 15% (1680×1.15=1980CFM) for a darker colored roof. My roof is forest green. So an exhaust fan with a minimum rating of 1980CFM/300=6.44 sq ft, which would determine the gable vent size on the west end of the building. Examples: 30”x32”=6.65 sq ft or 26”x36”=6.48 sq ft) My question is are these formulas correct and which one do you recommend using? Two gable vents, a gable vent and a shutter exhaust fan, something different or nothing at all? I just want to do this right and make sure my attic has sufficient ventilation once it’s enclosed. I hope to hear back from you. Thanks! 

Last questions. I found a 36×36 square gable vent that has a NFVA of 585. I need 576 on both sides of my building so this vent should be sufficient, correct? Also, with me using the 1/300 ventilation rule the gable vent company who has this vent recommended using a vapor barrier in the attic too. I believe he said that it needs to be no more than 1 perm and to install it on the warm side of the attic. He said this is needed because I’m not using the 1/150 rule. He said if I have 16 sq ft on ventilation instead of 8 I wouldn’t need a vapor barrier. That’s not really an option though. That many gable vents wouldn’t look good. So what do you think? Do I really need a vapor barrier using the 1/300 rule? My roof panels have a felt-like material on the underside of them that I believe is called “drip x”. I was under the impression that this was a vapor barrier and when warm air rises and hits those cold roof panels the “drip x” keeps it from condensing. Do I really need a vapor barrier along the warm side of the attic too? That sounds like overkill to me but I want to do it right too. The plan is to fully finish the inside of my outbuilding eventually with a ceiling that will be white ribbed panels with a r-38 blown in fiberglass. I only plan on heating the building to about 55-60 degrees and that’s only if I’m out there working. The thermostat will be set to 45-50 if I’m not out there. Also, this outbuilding doesn’t currently have air conditioning but I may consider adding it down the road. You’ve been a big help so far. Thank you and I look forward to your response. “

Mike the Pole Barn Guru responds:

As long as your four square feet (576 square inches) of NFVA (Net Free Ventilation Area) is located in the upper half of each gable endwall, your formula is correct and should provide sufficient ventilation. Actual vent size is not the same as the NFVA – so look closely before investing in any particular vent.

A vapor barrier would only be needed if you have over 8000 heating degree days. One of those vents on each end should do the trick. 

You can look up your heating degree days here: https://www.huduser.gov/portal/resources/UtilityModel/hdd.html

This entry was posted in Pole Barn Planning, Ventilation, Pole Barn Heating and tagged , , , , , , , on by .

Gable Fan, Clay Soils, and Condensation Issues

This week the Pole Barn Guru answers reader questions about use of a gable fan to prevent condensation, building with posts in clay soils, and addressing condensation issues in a three-stall garage.

DEAR POLE BARN GURU: I have been reading some post on your site about gable vents. I have a 40×80 building with spray foam on the bottom of the roof, which is sheeted with plywood. The walls have rigid foam and fiberglass. Question is, would an electric gable fan help or hurt condensation in the building, and is it even necessary. Much of the building will become heated and cooled living space. STEVE in SOMERSET

DEAR STEVE: It is very possible a humidity controlled electric fan would assist in reducing condensation, however before moving forward with it, I would recommend you consult with your HVAC provider, as a properly designed heating and cooling system can be set up to provide adequate air exchanges and control humidity.

 

DEAR POLE BARN GURU: I have heavy clay soil that does not drain. If I put posts in ground the bottom 2 feet will be soaked most of the year. Should I use concrete piers or will proper treated post be ok? MATT in MORRISTOWN

DEAR MATT: Having personally built a post frame combination garage/shop/mother-in-law apartment at our son Jake’s then home near Maryville, I feel your pain when it comes to Tennessee clay soil. Properly pressure preservative treated columns are not negatively affected by ground water, however you have other factors to consider before moving ahead with your build. You’ll want to read these articles discussing them: https://www.hansenpolebuildings.com/2019/06/post-frame-construction-on-clay-soils/ and https://www.hansenpolebuildings.com/2020/07/barndominium-on-expansive-soils/.

 

DEAR POLE BARN GURU: Hello, We are building a 3 garage pole barn and would like to know if you suggest the following:
A. Can you spray foam insulation to house wrap and do you leave the paper under mullions if removing the paper?
B. We have sweating on our house wrap and in our bay that will be mostly finished we put insulation boards which had paper on both sides and now will have to remove that side siding to remove it.
C. Our bay 3 floor is just stone, the others are concrete. We didn’t put a vapor barrier plastic under stone, so until spring when we remove stone and do this we were thinking of laying a tarp tight on stone to hold back any moisture into the rooms for humidity and condensation. What do you suggest? LAURIE in NEW YOUR

DEAR LAURIE: While there are some installers who will spray foam to a WRB (Weather Resistant Barrier aka house wrap), we do not recommend it https://www.hansenpolebuildings.com/2020/04/spray-foam-insulation-3/

vented-closure-stripIf you are getting condensation inside of your WRB it is due to excess moisture in your building. You need to eliminate or minimize sources of water vapor (seal any concrete slabs-on-grade if a well-sealed vapor barrier was not installed beneath). Proper ventilation from eave to ridge will also help to alleviate this challenge.

Provided you can well-seal a tarp, it is certainly a better option than just leaving raw stone exposed.

 

This entry was posted in Columns, Insulation, Pole Barn Questions, Pole Barn Design, Pole Barn Heating, Pole Barn Planning, Ventilation, Building Interior and tagged , , , , , , , , , on by .

Venting an Attic

Saving Money When Venting An Attic?

While some of you may think I have been doing post frame buildings since dinosaurs roamed our planet, I can assure you this is not true. Now my youngest son, when he was pre-school aged, did ask me (in all seriousness) what was it like watching space aliens build Egypt’s pyramids!

When reader DOMINIC in FESTUS wrote his question to me, it got me thinking about when I first had a client ask for a building with insulation at ceiling level. While I truthfully do not remember, in my first 6000 or so post frame buildings (we are talking 1980s here) I doubt there were more than a handful.

Fast forwarding to today’s modern fully engineered post frame buildings and nearly every building – garage, shop, barndominium, etc., is going to be climate controlled to some extent and most of these have enclosed attic spaces with insulation to be placed at ceiling level.

Here is DOMINIC’s question:

“I will be building a 30×40 pole barn soon. I plan on putting a ceiling in with insulation. My question is on attic venting. It seems best practice is to use a ridge vent with vented soffits but are gable vents alone sufficient? It would be cheaper for me to just do gable vents.”

Your best practice is to have even airflow from eave intakes to ridge exhausts. If your building will have sidewall overhangs, you might as well take advantage of this. You COULD (as an alternative) utilize gable vents. Provided at least half of your gable venting is located in the upper half of the attic, you can get by with as little as 576 square inches of NFVA (Net Free Ventilation Area). To achieve this would require (3) three 20″ x 30″ gable vents in each endwall. This could prove unsightly, difficult to install and is unlikely to result in being less of an investment than ridge vents. NOTE: a 20″ x 30″ gable vent provides roughly 106 square inches of NFVA (not 20″ x 30″ for 600″).

Of course, me being me, I had to snoop our records to see if he had requested a quote from us – and indeed he had…..

In looking over your quote from us, you may also want to consider increasing your overhead door width from 14′ to 16 (or even 18′) as you cannot safely get two vehicles side-by-side through a 14 foot wide door. For sake of resale value, with a 14 foot door it will appraise as a single car garage, wider doors will nearly double your appraised value as it is a two-car garage then.

This entry was posted in About The Pole Barn Guru, Building Overhangs, Ventilation, Post Frame Home, Barndominium, Insulation, Pole Barn Questions and tagged , , , , , , on by .

My Pole Barn is Chilly

Reader TIM from INVER GROVE HEIGHTS, MN has a chilling challenge, he writes:

“Fabulous site, congrats.  I have a 40×60 pole barn with 10ft ceiling to the bottom of the rafters.  Last year I put a 150k btu heater in to try and take the chill out a bit.  It didn’t work so well because the building is not tight at all.  I know I could spray foam it.  Is there anything that I could do less expensive?  I was told to put 6mil ply sheeting under the rafters at 10feet to seal that space and the leaks that are on the end of the building away from the space below where the heater is.  Plus I would not be heating the area above anymore.  I only heat it for a few hours 4-5 days a week.  Thoughts?”

Possible solutions could end up making two dollars per square foot of surface (for two inch thickness) of closed cell spray foam a bargain.

If you do not have some form of condensation control between roof framing and roof steel, you are going to need to closed cell spray foam the underside of your roof steel (again two inches), otherwise it will rain inside your building.

As heat rises, let’s begin there. Determine if your roof trusses are designed to support a ceiling load. This can be found by examining your engineered truss drawings supplied when trusses were delivered. If not available, look for the manufacturer’s stamp located on truss bottom chords. If you contact them with your site address, they should be able to pull up your building’s records. You want to find at least a five psf (pounds per square foot) ceiling (bottom chord) dead load (although three psf would support a steel liner panel ceiling). If inadequate to support a ceiling, your truss manufacturer can provide (for a nominal fee) a repair design to upgrade your trusses. Once it is determined trusses can support a load (or have been repaired in order to do so), add ceiling framing between trusses (if over two foot on center) to support drywall (my personal preference – use 5/8″ Type X) or a steel liner.

Blow in R-60 of fiberglass or cellulose insulation on top of your new ceiling. Make sure to not block airflow coming in from sidewall vented soffits. Should you not have a vented overhang and vented ridge cap, you will need to add gable vents located in the top half of each endwall with a minimum of 576 square inches of net free ventilation area in each endwall.

Made spray foam sound easy, didn’t I?

This entry was posted in Insulation, Pole Barn Questions, Pole Building How To Guides, Trusses, Ventilation, Workshop Buildings and tagged , , , , , on by .

Installing Steel Liner Panels in an Existing Pole Barn

Installing Steel Liner Panels in an Existing Pole Barn

Reader JASON in WHITEHOUSE STATION writes:

“ Hello! I have a post frame 30X40 Pole Barn that was built prior to me owning the house. Currently, the shop is not insulated. I would really like to insulate it, as it’s quite unbearable in the summer and winter. The building has soffit vents, a ridge vent, and two gable vents. With the way the building is set up with all that ventilation (possibly too much?), is putting in a ceiling with insulation on top my best bet? I know there are many options when it comes to insulation, but I am trying to determine what is best for my application. I am leaning towards 6 mil poly on the bottom side of the truss, ceiling liner panel over that with blown in insulation on top. My truss is 8′ on center. Is there a recommended length of panel I should use? Thank you for your help with this. I’m sorry if I asked too many questions.”

Mike the Pole Barn Guru responds:

Ceiling Loaded TrussesProvided your building has roof trusses designed to adequately support a ceiling load, your best bet will be to blow in insulation above a flat level ceiling. If you do not have original truss drawings available to determine if they have a bottom chord dead load (BCDL) of three or more, then you will need to find the manufacturer’s stamp placed on truss bottom chords and contact them with your site address. With this information they should be able to pull up records and give you a yes or no. If you are yet unable to make this determination, a Registered Professional Engineer should be retained to evaluate your trusses and advise as to if they are appropriate to carry a ceiling and if not, what upgrades will be required.

If your building does not have some sort of thermal break between roof framing and roof steel (a radiant reflective barrier, sheathing, etc.) you should have two inches of closed cell spray foam applied to the underside of roof steel, or else you will have condensation issues (even with the ventilation). With trusses every eight feet (again provided trusses can carry ceiling weight), I would add ceiling joists between truss bottom chords every four feet and run 30 foot long (verify from actual field measurements) steel panels from wall to wall.

You do not have too much ventilation – and be careful not to block off airflow at eaves. You can omit poly between liner panels and ceiling framing.

This entry was posted in Pole Barn Planning, Ventilation, Building Interior, Professional Engineer, Pole Barn Questions, Pole Building How To Guides and tagged , , , , , , on by .

Attic Venting, Moisture Reduction, and a Vapor Barrier

This week the Pole Barn Guru answers reader questions about ventilation for an attic space, what type of insulation to use for the reduction or elimination of moisture, and to place a vapor barrier under the concrete slab.

DEAR POLE BARN GURU: I know you have answered a few questions regarding attic venting so I apologize if this is a repeat. I am looking at finishing the ceiling in my 24′ x 48′ pole barn with thin gage interior steel and blowing in insulation. I currently only have soffit on one gable end and I can see daylight coming in from under the trim on the other end. According to some other threads I have read, I need 3.84 sq. ft. of venting area. The gable end soffit is approximately 25 sq ft but I don’t know how much of that is free venting area. Do you count the whole 25 sq. ft? Also, any recommendations for what to do on the other end? Is the daylight that I can see coming in under the trim good enough? BRYCE in ZIMMERMAN

DEAR BRYCE: By Code you are unable to count any contribution from gable end soffits and areas between overhanging end purlins should be blocked solid to prevent airflow (and to properly create a load path to transfer shear forces from roof to ground). A construction flaw (such as daylight coming in under trim, probably should be fixed, rather than counted. By Code requirement is 3.84 square feet or 552.96 square inches of net free ventilating area located in upper 1/2 of your building’s attic space. My recommendation would be to install gable vents sufficient to provide airflow requirements.

 

DEAR POLE BARN GURU: What type of insulation do I need to keep out moisture in my residential building? JACLYN in WHITEHALL

DEAR JACLYN: Here is my ultimate guide to post frame building insulation https://www.hansenpolebuildings.com/2019/11/post-frame-building-insulation/

More important is removing sources of moisture https://www.hansenpolebuildings.com/2018/10/pole-barn-moisture-issues/

 

DEAR POLE BARN GURU: I have nearly completed my DIY Hansen Building and am preparing to pour the slab. Is there a way to search the blog posts for my questions? I am wondering if I should install a vapor barrier under the concrete or wait and seal it after? Is 1/2″ rebar recommended? Should I use an 18in grid or can I go on the cheap and get away with 2ft? Planning on a 5 inch slab. NICK in GLIDDEN

DEAR NICK: Good to hear from you, we are looking forward to seeing photos of your new building!

You should install a well-sealed vapor barrier under your slab while Code requirement is 6mil, however 15mil is far less likely to be damaged during a pour. Run vapor barrier up sides and onto top of 2×8 splash planks Overlap seams by at least 6″ and tape. Most often we see 1/2″ rebar on a 16″ grid.

 

 

 

This entry was posted in Pole Barn Questions, Building Overhangs, Ventilation, Concrete and tagged , , , , on by .

Post Frame Condensation and Insulation Challenge

Solving Yet Another Post Frame Condensation and Insulation Challenge

Long time loyal readers will sigh as yet another post frame building has been erected without thoughts to how to properly insulate and control condensation. Had our new friend invested in a Hansen Pole Building, chances are good we would not be having this question and I would have had to write about something else today! Our Building Designers follow with these recommendations: https://www.hansenpolebuildings.com/2019/11/post-frame-building-insulation/.

Our new friend COREY in POST FALLS writes: 

“I have a 36×48 pole building with trusses on 12’ with BCDL 5psf, the roof is plywood sheeted with composition roofing with ridge vent and gable vents. The wall Purlins are on the exterior of the poles and there is no vapor barrier. I would like to install a ceiling with insulation and insulate the walls. I am looking for vapor barrier and insulation recommendations. Was thinking of installing 2×4 on 24 centers to bottom of trusses and installing OSB and blown in insulation, and then framing in between poles adding batt insulation and sheeting with OSB, but am unsure of controlling vapor. Thank you.”

Mike the Pole Barn Guru responds:

Small world, many years ago I graduated from Post Falls High School!

A vented ridge relying upon gable vents as an air intake is usually very inefficient. You should make sure your vents in each end are located in the top half of your attic and have at least 415 square inches of net free ventilating area on each end. This means you are probably going to have to add more vents. Effective ventilation of this area is essential to preventing mold and mildew in your attic.

Wall girts flat on column exteriors are inadequate to carry imposed loads and will not meet deflection limitations. I would suggest you reinforce each of them to create either an “L” or a “T”. Assuming you have 6×6 wall columns, you could place a 2×8 bookshelf style girt on top or bottom of each girt, nailing through 2×8 into existing girts with a 10d common nail at say 12 inches on center. This will create an insulation cavity and allow for easy interior finish.

For ceiling joists between your trusses, 2×4 will not be adequate you should use 2×6 #2 with joist hangers on each end.

Unless you have a Weather Resistant Barrier (https://www.hansenpolebuildings.com/2016/01/determining-the-most-effective-building-weather-resistant-barrier-part-1/) between framing and wall steel, my recommendation would be to have two inches of closed cell insulation spray foam to the inside of wall steel. Then fill balance of wall cavity with BIBs insulation: https://www.hansenpolebuildings.com/2011/11/bibs/ with a well sealed vapor barrier towards the inside space.

This entry was posted in Insulation, Ventilation, Pole Barn Questions, Building Interior, Pole Barn Design, Pole Building How To Guides, Pole Barn Homes, Pole Barn Planning, Pole Barn Structure, Barndominium and tagged , , , , , , , , on by .

Siding Materials, Fascia Boards, and Venting

Today’s Pole Barn Guru answers questions about siding materials, fascia boards and gable vents.

DEAR POLE BARN GURU: If a house or pole barn has metal on the outside does it still need plywood or OSB sheathing under the metal? GARY in JESUP

DEAR GARY: Provided steel siding and/or roofing has an ability to withstand snow, wind and seismic loads as well as adequately transfer shear – then probably not. Your building’s Engineer of Record can produce calculations to verify if underlying sheathing would be required for your particular building, at your particular site. This is one of a plethora of calculations done by Hansen Pole Buildings’ third-party engineers on every building we provide.

 

DEAR POLE BARN GURU: How is fascia installed on the ends of rafters? Should it be raised up to match the purlins? I have a pole barn with no overhangs. WAYNE in MARTINSVILLE

DEAR WAYNE: I will do some interpreting and guess your “rafters” are actually trusses and you have a building with trusses every two or four feet resting on truss carriers. With no overhangs, truss ends are capped by an “eave strut” or eave purlin – usually a 2×4 or 2×6 placed vertically. Top edge of your eave strut should be bevel cut to match your roof slope and installed so top beveled edge is in same plane with tops of adjacent uphill roof purlins (e.g. raised up to match purlins).

All of this information should be included in your engineer sealed building plans, as well as outlined in assembly instructions provided along with your building kit package (at least it is with those who invest in Hansen Pole Buildings).

 

DEAR POLE BARN GURU: Hello, I recently purchased an existing pole barn (30’ x 40’) which has no vents whatsoever.   The previous owner was reliant on just all the various air gaps and leaks for the building to breathe.  I would like to seal up some of those gaps for rodent control, and then replace those square feet of ventilation with actual vents.   

At a minimum, I’d like to put a gable vent on each end, and then probably some soffit vents as well.

I saw on your website a discussion of a 2-piece gable vent, designed to work over the ridges in pole barn siding.   Yet I don’t see where I could purchase those vents.   Can I buy those directly from Hansen, or would I have to go through a local dealer or contractor? GREG in DEARBORN

 

 

DEAR GREG: You can contact Justine@HansenPoleBuildings.com for a price and availability. For a building your size you will need 576 square inches of net free ventilating area – 1/2 on each end and located in upper half of your gable triangles.

 

 

 

 

 

This entry was posted in Pole Barn Questions, Steel Roofing & Siding, Pole Building Siding, Ventilation and tagged , , on by .

R Panel Gable Vents

R Panel Gable Vents

“R” steel roofing and siding panels are typically used on all steel buildings where larger spans occur between wall girts and roof purlins. With a three foot width net coverage, these panels have a 1-1/4 inch tall high rib every 12 inches with two low stiffener ribs between. R panels do not have a full underlapping (or purlin bearing) underlap. This lack of a purlin bearing underlap makes this product both less expensive (as it can be roll formed out of a narrower steel coil) and more difficult to install. Without careful placement at laps, panels tend to “walk” with one or both panel ends covering more or less than the necessary three feet.

Very few all steel buildings make provisions for ventilation. Rarely do they include sidewall eave overhangs, leaving no place for an eave air intake through a vented soffit.

So, how to vent?

Reader STEVE in PHOENIX writes: “Mike,
Hello. I’ve been researching venting options for an existing clearspan type red steel metal building and was directed to your snap in style gable vents for ribbed metal panels.  My building is covered with R panel metal siding…..the high ribs are 12″ on center (pic attached). I’ve been working with Justine on selection and pricing of your gable vents.  Will your vent panels work with this siding and if not, do you have a venting solution for this building? Thanks.”

My reply:

R panels typically have 1-1/4″ high ribs. I do not believe the snap ring vents will work with ribs higher than 3/4″ (Justine can confirm). If not, then you could use a standard gable vent with a J Channel surround. Just like snap ring applications, cut the hole in siding for the vent (make it 1/4″ taller and wider than the vent you will push through the hole). Cut J Channels to fit the vent, with interlocking and overlapping corners (just like a non-integrated J Channel window). Insert individual pieces of J Channel into the hole, joining corners as you go. Slide vent into J Channel “picture frame” using lots of caulking between vent and J Channel and at each of the J Channel corners.


Snap ring vinyl gable vents (https://www.hansenpolebuildings.com/2018/07/vinyl-gable-vents-for-pole-barns/) make installation a breeze and can quickly be installed in post frame buildings with steel siding with ribs no higher than ¾” . When designing your new post frame building discuss ventilation with your Hansen Pole Buildings’ Designer at (866)200-9657.

This entry was posted in Ventilation, Pole Barn Questions, Pole Barn Design, Pole Building How To Guides, Steel Roofing & Siding and tagged , , , , on by .

Venting an Attic Without Soffit Air Intake

Venting an Attic Without Soffit Air Intake

Loyal reader KEN has an attic space with only air exhaust points – a vented ridge, and no air intake. His dilemma, how to adequately ventilate his attic without vented soffits.

Ken writes:

“I finally was able to make contact with the manufacturer of the open foam like material used under my ridge as a vent. The following is cut and pasted from their technical material: Net Free Area 1”nom.Thickness 8.5 sq.in.per lin.Ft.per side (17 sq.in .per lin.Ft.ridge).  Since I have a 60 foot ridge, that would equal 1020 sq. in. or 7 sq. ft. 

Given the ridge vent, do you still recommend 3 sq. ft.  venting on each end?

You note that an 18×24 would provide 140 sq in (or 0.97 sq. in.), but 18×24 is 432 sq in.  Do the louvers and other components reduce that by a factor of 3, just wanting to confirm.  With a 3 sq. ft. requirement, I would need a vent nearly 3 times an 18×24.  Maybe it just comes down to not the ideal but what can be practically installed. 

In order to prevent rust at the cut line, should I caulk the outside seam where the louver comes through the wall?”

Mike the Pole Barn Guru writes:

Another way of thinking about ventilation – view it like a straw. Obviously with best (and most) straws each end has an opening. What happens when a hole exists somewhere between ends? A reduction occurs in your ability to draw up water or soda. A similar effect happens when different vent types are employed over a shared air space.

Air and water are similar, their flow follows a path of least resistance. In a properly designed and installed attic ventilation system air flow travels from intake vents to exhaust vents, flushing out warm, humid air along roof deck (think underside of roof steel). However, if two or more different types of exhaust vents (gable and ridge) are used above a shared attic air space, one exhaust vent will likely to interrupt air flow to the other. In this arrangement it becomes another intake vent for a primary exhaust vent – leaving large sections of attic space incorrectly vented.

I would be inclined to seal ridge vent off and utilize gable vents. Dimensions of gable vents are overall unit dimension, not net free area (reduced from overall size by both exterior framework and louvers). Each endwall may require multiple vents in order to achieve an adequate airflow.

Caulking cut edges of endwall steel would certainly not hurt. A suggested caulking would be TITEBOND Metal Roof Translucent Sealant.

 

 

 

This entry was posted in Pole Barn Structure, Ventilation, Pole Barn Questions, Pole Barn Design, Building Overhangs and tagged , , , on by .

My Pole Barn Needs Ventilation

My Pole Barn is a Sauna in Summer- and needs ventilation!

“Hey there Pole Barn Guru, got a question about ventilation.

Just bought a house with a pole barn on the property. I believe it’s only about a year old. 30 x 32.  It has no soffits or windows, only a standard garage door and walk-in door.

Metal siding and roof, and the underbelly of the roof has a vapor barrier. There are also two ceiling fans in here.

I don’t care that it’s cold inside the building in winter, but it’s like a sauna now in the summer.  I was thinking of an exhaust fan to pull out the heat, but I don’t know if that’s waste of money. How does one ventilate this thing without having to bulldoze it and start over?

Thanks.

Dezy”

Mike the Pole Barn Guru responds:

Since you cannot increase the amount of venting in your soffits (as you have none), you’ll need help from power vent fans.

Attic vent fans can be hard-wired and equipped with a thermostat and/or humidity sensor so they automatically cut on at a preset moisture level or temperature. You could also install solar-powered attic vent fans, though it has been found most solar models aren’t powerful enough to be very effective.

To determine what size power vent fan(s) you need for your attic, you first need to know the size of your attic in square feet.

Attic Size

To determine the size of your attic, multiply the width by the length of the attic floor in feet. In your case 30′ wide x 32′ long = 960 square feet of attic space.

Vent Fan Size

Next, multiply the square feet of attic space by 0.7 to get the minimum number of cubic feet of air per minute the fan should be rated to move. 960 sft x 0.7 = 672 CFM minimum fan rating.

Add an additional 20% (CFM x 1.20) if you have a steep roof, and 15% (CFM x 1.15) for a dark roof. Attic vent fans are commonly rated from 800 to 1,600 CFM, making one fan suitable.

Vent Fan Location

Install gable mounted fans on the gable vent at end of the building facing away from the prevailing winds.

Intake Air Vents

It’s also important to have plenty of soffit or gable vents for the fan to draw air into the attic. To find out if you have enough vent space, divide the cubic feet of air per minute the fan(s) is rated for by 300 to come up with the minimum number of square feet of intake vent space needed for that size fan. 672 CFM ÷ 300 = 2.24 sq. ft. intake vent area

If you prefer the answer in square inches rather than square feet, multiply the answer by 144 and round to the nearest inch (2.24 x 144 = 322.56 sq. in. vent area).

 

This entry was posted in Ventilation, Pole Barn Questions, Pole Building How To Guides and tagged , , , , , , on by .

Mold in a Post Frame Building Attic

Hansen Pole Buildings’ client BRENT in WASHOUGAL writes: “We have your 40×80 pole barn built sept. 2014, and it’s having problems with mold forming over the purlins. I’m wanting to know my options to prevent a future problem.

Thanks.”

Mike the Pole Barn Guru responds:

First – get rid of the mold. Mix in the ratio of one cup bleach per gallon of water and use a hand pump sprayer to saturate all moldy surfaces. You can also use a scrub brush to remove the existing mold.

The most common causes of attic mold are leaking roofs, inadequate ventilation and too much humidity in the building itself. If your concrete floor has a vapor barrier underneath it and/or is well sealed, you are probably not drawing in excess moisture from underneath the building – so we will look at the first two.

Mold showing along the tops of the roof purlins and not on the trusses, as well as the streaks down the sides of the purlins leads us to believe you may have screws which were inadequately placed. Screws which are not properly seated so as to compress the rubber washer, will leak. Screws which are driven in at an angle will also cause leaks. The roof should be investigated screw-by-screw to make sure all screws are properly driven. Water leaking around a screw shaft will eventually cause decay of the wood around the shank, so if screws cannot be tightened they should be replaced by a larger diameter and longer screw – in your case a #14 diameter by two inch long part.

Ventilation – in an ideal word your building would have had enclosed vented eave overhangs of 18 inches or greater on both sidewalls for an air intake, as well as a vented ridge to provide an exhaust point. This ventilation system provides for even airflow from eave to ridge throughout the entire attic area. Gable vents can be used to meet Code requirements for ventilation, however the reality is they are not very effective in providing ventilation other than near each end of the building’s attic. The Code requirement would be for 1/300th of the footprint area of the attic to be provided for as net free area of venting, as long as at least 50% of the venting is in the top half of the enclosed attic space. With a 40′ x 80′ building, you have 3200 square feet of footprint, which would require at least 10.67 square feet (or 1536 square inches) of net free ventilating area. To give an example a Mid America (www.midamericacomponents.com) Classic Rectangular vinyl vent 20 inch by 30 inch provides 297 square inches of net free ventilation area, so it would take three of these in each endwall just to meet the requirements of the Code!

There also is a difference between meeting Code requirements and what actually works in a real life situation.

Since you cannot increase the amount of venting in your soffits (as you have none), you’ll need help from power vent fans to exchange the moist air in your attic for dryer, outside air. Attic ventilation fans would help move the moist air out of the attic without giving it time to find a home on the purlins and trusses.

Attic vent fans can be hard-wired and equipped with a thermostat and/or humidity sensor so they automatically cut on at a preset moisture level or temperature. You could also install solar-powered attic vent fans, though it has been found most solar models aren’t powerful enough to be very effective.

To determine what size power vent fan(s) you need for your attic, you first need to know the size of your attic in square feet.

Attic Size

To determine the size of your attic, multiply the width by the length of the attic floor in feet. In your case 40′ wide x 80′ long = 3200 square feet of attic space.

Vent Fan Size

Next, multiply the square feet of attic space by 0.7 to get the minimum number of cubic feet of air per minute the fan should be rated to move. 3200 sft x 0.7 = 2240 CFM minimum fan rating.

Add an additional 20% (CFM x 1.20) if you have a steep roof, and 15% (CFM x 1.15) for a dark roof. Attic vent fans are commonly rated from 800 to 1,600 CFM, making one fan suitable for attics of up to around 1160 square feet, even with a steep, dark colored roof.

Vent Fan Location

Install gable mounted fans on the gable vent at end of the building facing away from the prevailing winds.

Intake Air Vents

It’s also important to have plenty of soffit or gable vents for the fan to draw air into the attic. To find out if you have enough vent space, divide the cubic feet of air per minute the fan(s) is rated for by 300 to come up with the minimum number of square feet of intake vent space needed for that size fan. 2240 CFM ÷ 300 = 7.47 sq. ft. intake vent area

If you prefer the answer in square inches rather than square feet, multiply the answer by 144 and round to the nearest inch (7.47 x 144 = 1075.2 sq. in. vent area).



 

 

This entry was posted in Pole Barn Questions, Building Overhangs, Ventilation, Fasteners and tagged , , , on by .

Minimizing Condensation When Building Over an Existing Foundation

Minimizing Condensation When Building Over an Existing Foundation

Reader ROSS writes:

“Hello, I have a question about venting of my building. I currently am in the process of building a shop myself. I had an existing foundation of 75 x 42 that had 8ft concrete walls all the way around. I’m building my building on top of this to give myself 17’ sidewalls. My concern is about my venting. I’m planning to have soffit installed along the building and am not sure if I should go with Gable vents or ridge vents. The building will be insulated with 3” fiberglass with a poly vapor barrier on the walls and with 1” 4×8 sheets of foam board on the roof with all the joints taped. My concern with ridge vent is will moisture condense on the exposed ridge cap and drip since it has to be left uninsulated for venting or will it be ok? I would rather not have any drips. My gut feeling tells me I need to have plenty of venting since 3 sides of the concrete are covered with dirt and already show condensation pretty regularly when the temp changes. With my soffits do I need to run vented soffit the full length of the building? Thanks your response will be greatly appreciated!”

Mike the Pole Barn Guru Responds:

I’d start with excavating around the foundation and properly sealing it from the outside, as well as sealing the slab floor. It sounds like you propose to place foam insulation board between the roof framing and the roof steel – not a good structural idea, as you are significantly reducing (if not eliminating) any shear strength afforded by the steel panels, as well as eventually contributing to leakage from the screws being able to “work” between the framing and the steel. You would be ahead to either use a radiant reflective barrier (less expensive, more labor intense) or Condenstop/Dripstop (read more here: https://www.hansenpolebuildings.com/2014/07/condenstop/) beneath the roof steel. Either one of these products can be adhered to the ridge caps as well.

The Building Codes do not allow for gable vents to be combined with eave or ridge vents. Your best bet is to run full vented soffits on both eaves, combined with ridge vents the entire building length. https://www.hansenpolebuildings.com/2014/02/pole-building-ventilation/

 

This entry was posted in Roofing Materials, Pole Building How To Guides, Pole Barn Planning, Ventilation, Concrete, Footings, Insulation, Pole Barn Questions and tagged , , , , on by .

Which Insulation to Use?

Welcome to Ask the Pole Barn Guru – where you can ask questions about building topics, with answers posted on Mondays.  With many questions to answer, please be patient to watch for yours to come up on a future Monday segment.  If you want a quick answer, please be sure to answer with a “reply-able” email address.

Email all questions to: PoleBarnGuru@HansenPoleBuildings.com

DEAR POLE BARN GURU: We live in Texas. Can we use your configuration tool and have ya’ll create a plan for us? We will be building the barn ourselves.

If so, how much would the plan be for a 24 by 40 pole barn, 12 foot side walls, 6/12 roof pitch, one garage door, one personal door and 4-6 windows?

Thanks, Dan

DEAR DAN: We’d love to help you out with your proposed project – in fact it is what we do every day! Our system is totally geared to people who want to find the most savings as well as enjoying the pride of ownership which comes with a job well done.

Mike the Pole Barn Guru

DEAR POLE BARN GURU: We are undertaking a project of insulating our indoor riding arena/pole barn. We are installing the ceiling to the bottom of the trusses (got the ok from a structural engineer). We cannot decide what would be the best type of insulation to put in top of the ceiling. The choices: 1) spray foam, too toxic, too expensive. 2) blown cellulose/paper product-worried if it gets wet through the roof vent, worried that critters nest in it, worried that it blows around (from roof vent) 3) fiber glass – carcinogenic if you breath it in, while installing mostly, degrades through the years, critters can nest in it. 4) hard sheets of Styrofoam – like that it is solid, won’t rot if wet, won’t blow around, 4 x 8 sheets fit in between the trusses, don’t know if the “R” value is high enough or if it would insulate enough. We can’t decide what would be best. The ceiling is 29 gauge metal panels, looks like roofing. Question from Cindy in Warwick, NY

DEAR CINDY: Trying to insulate an indoor riding arena will literally be an undertaking and there is a strong possibility it will prove to be an untenable task just trying to heat the huge volume of space.

Before getting too deeply into your challenges, there needs to be a thermal break between the roof framing and the roof steel. If one was not installed at time of construction, the best choice might be to have a thin layer of spray foam placed on the underside of the roofing.

The other option would be to remove the roof steel, place the reflective radiant barrier and then reinstall – which could easily be quite an undertaking.

With the condensation problems solved, ventilation is the next step to tackle. If you have vented overhangs and ridge, it is probably adequate. If not, an entire new set of issues awaits you – as gable vents will become the only Code approved method of ventilation. If water is coming through your ridge vent, then it was done incorrectly (either wrong product, or poor installation) and should be replaced or repaired.

My recommendation is going to be blown in either cellulose or fiberglass. It is going to give you the highest R value per dollar. A professional installer can blow it in, removing the risk of you inhaling. In your part of the country you should probably be looking at as high as R-60. Once installed the probability of the insulation blowing around in your attic is small and even a nominal amount of settling can be handled by adequate thicknesses to begin with.

As far as degradation of blown insulation – we are talking about decades, not months or years. If you do blow in insulation and have vented eaves, be sure to place insulation baffles (cut from high R foam board) appropriately to keep insulation from falling into the overhangs. The baffles also allow an inch of clear net airflow over the top.

Mike the Pole Barn Guru

DEAR POLE BARN GURU: I want to submit two requests for quotes – one for a larger building and one for a smaller building – because I don’t yet know if the house I will decide to buy and renovate will have an attached garage or not.  If it does have an attached garage, then I would go with the smaller building.  If the house does not have an attached garage, then I will want to go with the larger building.  Both buildings would need a back overhead door for driving our trailered boat in through the back and out the front.   Both buildings would need one taller and wider opening for the boat and either one or two smaller openings for cars/equipment.  Both buildings would have wainscot, single-hung windows, all metal roof and siding, no skylights, eave lighting, ridge vent, etc.

I am thinking of a residential pole gable building garage/workshop combo for my husband’s home workshop, home lawn and snow equipment, 22′ boat on trailer, shelving storage, etc.

Can I submit more than 1 request for a quote on-line or would it be better to talk with a customer rep on the phone and/or submit drawings, or wait until I find the house that I am going to renovate in order to see if it has any attached garage?

Thank you,
Double Requests

DEAR DOUBLE: Some of the answer depends upon your goals. If you need some sort of budgetary figures only, to assist with your house purchasing adventure, then requesting multiple quotes online will be a quick way to get started.

Ultimately, until you have actually purchased a property, any preliminary information is going to be just what it is – preliminary. The best dictate for what you will eventually build will be determined by the property you will be building on.

Once you have an idea – you can get more than one quote either online, or by calling the toll-free number listed on the website – one of our building designers will be happy to assist you in your planning.

A caution – be sure to talk with the Planning Department which has jurisdiction over any property you are considering purchasing. There may be restrictions on what you will be allowed to build and it is best to find them out prior to signing the check.

Mike the Pole Barn Guru

This entry was posted in Insulation, Pole Barn Questions and tagged , , , on by .

Pole Building Ventilation

Ridge vent without soffit vent

One of the most overlooked areas of pole building construction is proper ventilation. Lack of proper pole building ventilation becomes even a greater issue when an enclosed attic space is present. The International Building Codes require any dead attic space to be ventilated. Without adequate ventilation, moisture from condensation will begin to accumulate on top of the ceiling. Mold and mildew can form on the underside of the roof sheathing and on the roof trusses.

One of the least expensive options for a new pole barn, especially with steel roofing, is to have a vented ridge. Very easily installed at time of construction, if there is ever a possibility of a flat, level ceiling being installed in the building, a vented ridge is a must.

A ridge vent without a soffit vent doesn’t work, and here’s why. By virtue of their design and location on the roof, ridge vents are predominantly exhaust devices. Warm moist air from inside the building rises, passes through the ceiling material and attic insulation and out through the highest point – the ridge.

The attic space will get makeup air to replace the air the ridge vent has exhausted along the path of least resistance. If there is plenty of soffit venting and if you have a relatively tight ceiling, then the makeup air will come from outside, which is desirable, summer and winter. However, without soffit vents, the makeup air comes from indoors, a situation which is not desirable in any season.

So what to do if you have a building with an attic space, and little or no ventilation?

If mold is already a problem, scrub the affected areas with a diluted bleach and soap solution. Once clean and dry, a mold resistant paint can be applied.

I’ve heard others suggest a roof design without ventilation, an issue that is volatile and multifaceted. Basically – doing away with the dead air space in the attic. As I see it, the choice to go or not to go with attic ventilation does not in itself ensure good performance. The bottom line with attic assemblies, whether vented or not, is that they be done properly.

Filling the attic space with cellulose insulation may be an option, although expensive and is not a 100% guarantee to solve the problem. Cellulose insulation is dense, blocks airflow and contain salts which inhibit mold growth. In my opinion, many of the innovative uses I’ve seen for cellulose are experimental, but those experiments seem to be working well. If conditions permit, you could find a way to blow in cellulose at the gable ends of the trusses. Better yet, you could fill the truss cavity from the ridge. In any case, with cellulose insulation as a “total fill”, I recommend the use of a vapor barrier, such as plastic sheeting on the underside of the trusses and/or ceiling joists or a vapor-barrier paint applied over the drywall.

Only without a dead air space should a ceiling vapor barrier be utilized.

Maintaining low indoor humidity may be also effective, but it may require wintertime humidity below 25%, which could be uncomfortable, as well as near impossible to achieve.

Add Pole Building Ventilation.

If your pole building does not have enclosed vented overhangs, it may be possible to add ventilation along the top of the building sidewalls. However, each individual case should be examined, as drilling holes or cutting into a structural member could compromise the building’s integrity.

If a continuous ridge vent is not present, install one. Make certain there is a clear air flow from the attic space through the ridge – which may entail the removal of any sheathing (oriented strand board – OSB or plywood), vapor barriers, or other insulations directly beneath the ridge.

Although the newer versions of the Code prohibit the combination of gable vents and ridge vents, gable vents may be installed in each end of the building – to provide an intake for outside air.

The real solution – is to build it right in the beginning. Prudent design with vented soffit overhangs and a vented ridge may involve some initial investment, but prove to be an insignificant cost over the life of the building. And trust me, no one I’ve ever talked to had a “fun” time dealing with mold.

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Dear Pole Barn Guru: Ventilation for an Old Pole Barn?

Welcome to Ask the Pole Barn Guru – where you can ask questions about building topics, with answers posted on Mondays.  With many questions to answer, please be patient to watch for yours to come up on a future Monday segment.  If you want a quick answer, please be sure to answer with a “reply-able” email address.

Email all questions to: PoleBarnGuru@HansenPoleBuildings.com

DEAR POLE BARN GURU: I am getting ready to insulate and heat an older pole barn so I have signed up here for some help and advice. So, I have an older pole barn that really has no eave/soffit vents or ridge vents. It’s pretty crude built. I want to insulate and add a ceiling. My concern is condensation in the attic after insulating. I plan on adding some sort of full ridge vent. Then I need some eave venting or add gable vents. The idea of adding gable vents makes me nervous because I don’t know how to seal them properly with the ribs in the metal siding. I will attach pics. Is there a way I can build in some eave vents? The metal roof just comes down the sides of the barn and there is an air gap between the rood and the siding that is covered by the white trim/flashing as seen in the pictures. Any ideas on what to do with this old barn before I start finishing it would be a big help. I also thought about attic fans in the ceiling. CB MAN

DEAR CB: You asked for advice, so here it is….your old building has some challenges when it comes to attempting to heat. The ventilation issue is just one of many. The building has no insulated vapor barrier under the roof steel to prevent condensation, which you have touched upon. Two other factors, either of which could be deal breakers – the building has horizontal sliding doors, which are impossible to properly insulate and seal, without them becoming permanently affixed, and the roof trusses are probably not designed to support the weight of a ceiling.

With all of this said, you have two really good solutions – the least expensive is to just put up another new pole building, designed properly to be climate controlled, using your existing building for cold storage. The other – knock this building to the ground and rebuild at the same location.

Assuming you may not be interested in either of these, and want to pour lots of money into a building you refer to as “crude built”; I will give you some solutions.

Toughest first – the trusses. As they are prefabricated wood roof trusses, there should be a manufacturers stamp on every truss. The design loadings might be stamped on the trusses (due to the age of your building the “might” is the operative word). With this information and the location of your building, I could probably give you an idea as to adequacy. If the truss manufacturer’s name can be found – see if they are still in business. If so, they can determine adequacy for you (for a small fee) and get an engineered repair if they are not adequate. If those fail, hire a registered engineer to do an evaluation for you.

Condensation under the roof steel…as the steel is nailed on, it cannot be removed and an insulated vapor barrier (something like A1V reflective insulation available from www.buyreflectiveinsulation.com) added. The best solution is probably going to be to spray foam insulate the underside of the roof steel.

Adding a ceiling – with the trusses verified for the ability to take the load (and correctively upgraded if needed), 2×4 ceiling joists can be placed between the bottom chords every two feet, with LU24 or similar joist hangers at each end.

Screw on 5/8” Type X gypsum board to the underside of the ceiling joists and trusses (it won’t span four feet, so don’t even attempt to). Leave an attic access hole somewhere close to the center, so insulators can blow in the desired thickness of insulation. Do NOT place a vapor barrier between the ceiling drywall and the framing above.

Ventilation – the new codes do not allow for gable vents to be mixed with eave and ridge vents. It is…use one or the other. Take the square footage of the footprint of your building, and divide by 300. This gives the net square inches of ventilating area which must be provided in each gable end of the attic. Hansen Pole Buildings has vinyl gable vents, in a myriad of colors, with snap rings. A hole is cut in the steel (using the snap ring as a template), the vent is pushed through from the inside, and the snap ring is then pushed on from the outside (this is a two person job). These vents are designed to accommodate ribs on steel panels.

Now the roof is taken care of, the walls are the next challenge. Remove the sliding doors and frame the openings down in size to fit insulated steel sectional overhead doors. You may be able to salvage the steel off the sliding doors, and if done carefully, use the pieces to fill in the gaps.

Again, the nailed on wall steel becomes a limiting factor….spray foam for the walls is probably the best solution. Keep in mind, you will need to put either drywall or a steel liner panel on the inside of the columns, as Code does not allow spray foam to be left exposed to heated areas.

Good luck – and let me know what choice you make and how it turns out.

DEAR POLE BARN GURU: We just made a phone call to Menard’s to order over a hundred bags of blown-in cellulose. While talking to the guy in the building department, he asked if this is for a pole barn, Told him yep. He then strongly emphasized to NOT use blown-in cellulose above the metal ceiling because the flame retardant material will rust and eat up the ceiling. This is the first I have heard of, so I did some quick research online and it looks like they have some kind of acid that act as a flame retardant.

Right now, our 30×48 gambrel pole barn with loft are being built. The shop will be finished with R-19 fiberglass in the walls and then T1-11 panelings will be installed. The ceiling is going to be a metal liner, obviously. The loft will be used for storage and man cave, so half of the loft would be finished in the future. There will be Low-E condensation barrier below the roofing, so the contractor told us there is no need for a vapor barrier in the shop ceiling where I would be blowing the cellulose.

Right now I am not sure what to think. Several months ago I did some research and have decided to plan on blown-in cellulose. Is this something I should be concerned about? What should I do to avoid the rusting issue the guy told me about? BTW, he told me to instead use blown in fiberglass which is something I am not thrilled about. Thanks. PERPLEXED

DEAR PERPLEXED: If the fiberglass and cellulose insulation people would spend more time promoting what each of them do as good, and less time shooting broadsides at each other, life would be so much better and they would probably each sell more product.

There have always been concerns about insulation causing corrosion when in direct contact with metal building components such as sweaty pipes, electrical wires or metal boxes, etc. Consequently, ASTM (American Society for Testing and Materials) standards for every insulation material contain testing which specifically addresses these concerns. In addition, in 1979, the CPSC (Consumer Product Safety Commission) promulgated a law, which regulated the fire and corrosive characteristics of cellulose insulation. A statement of compliance with these requirements is required on every bag of cellulose insulation. The types of metal tested with all insulation materials are copper, aluminum, steel, and additionally in Canada, galvanized steel. The test requires placing soaking-wet cellulose insulation with an imbedded .003-inch thick metal coupon inside a humidity chamber under conditions that are ideal for promoting corrosion. After 14 days, the metal coupons are removed, cleaned, and examined under a light to detect the smallest pinhole. In all, there are two coupons of each metal and all must be free of even one pinhole. This is a very strict test!

My recommendations are to make sure your attic area is adequately vented (no less than 1/300th of the attic footprint area in venting, provided at least ½ of the vent area is in the top ½ of the attic), make sure the insulation stays dry (no roof leaks), and do not have a vapor barrier between the ceiling and the insulation. Whether you choose fiberglass or cellulose, either should be fine.

This entry was posted in Insulation, Pole Barn Questions, Ventilation and tagged , , on by .
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