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Insulation for Existing Building, Screws to Replace Nails, and Rusted Steel

This Wednesday the Pole Barn Guru answers reader questions about insulating a metal post frame garage in Florida with vented soffits and peak, replacing nails with EPDM gasketed screws on an existing structure, and ideas to replace rusted steel on the lower 3′ of a structure.

DEAR POLE BARN GURU: I have a metal post frame garage in south central Pa. I want to insulate this building. It is metal siding screwed to 2×4 wood purlins. It has vented soffits and is vented at the peak of the roof. How would I go about insulating this building? My hope is to use Polyiso foam board and insulate the slope of the roof, not the flat ceiling. Please give some advice for air gaps and vapor barriers for the roof and methods for insulating the walls. JASON in MANHEIM

DEAR JASON: Unless you are willing to use closed cell spray foam applied directly to underside of your roof steel, sealing off soffit and ridge vents, you are stuck without being able to insulate with slope of roof.

Why? Air impermeable insulation must be installed either directly above or below your roof deck – your roof purlins negate ability to consistently do this. Otherwise, an inch or more of unobstructed airflow must be provided directly below roof deck from eave-to-ridge (again, purlins are obstructing). Insulting at ceiling level is indeed your best bet. Install a ceiling and blow in granulated Rockwool (best) or fiberglass. Walls – completely fill insulation cavity with Rockwool batts, use a well-sealed interior vapor barrier (6mil or thicker clear visqueen).

 

DEAR POLE BARN GURU: I have a 1000sf metal building with Galvalume roof (on 2×10 purlins, no deck) built in 1999 with gasketed nails. I’m experiencing some small leaks from some of the nails. The metal is still good. Do you know someone that can replace the nails with screws, approximately 800. MIKE in CINCINNATI

DEAR MIKE: I would recommend posting on your local craigslist under “gigs” for a project such as yours. Nails should be replaced by #14 diameter screws, ideally with at least a 1/2″ greater penetration into wood than your nails. Look for screws with EPDM rather than neoprene rubber gaskets.

 

DEAR POLE BARN GURU: The bottom 3′ of our metal sided maintenance shop has been rusted out by salt. Do you know of an organization that could replace the bottom sections? MARK in ROCHESTER

DEAR MARK: For local projects, such as yours, I normally recommend posting in your nearby Craigslist under “Gigs”. You will usually get a fair number of responses. You may want to consider replacing this lower portion with material other than metal – something resistant to ravages of deterioration due to chemical reaction of salt with metal

This entry was posted in Roofing Materials, Ventilation, Powder Coated Screws, Building Interior, Lumber, Fasteners, Insulation, Pole Barn Heating, Pole Barn Questions, Pole Barn Design, Barndominium and tagged , , , , , , , on by .

Insulation in Massachusetts, Code Restrictions in MN, and Insulation for In-Floor Heated Building

This Wednesday the Pole barn Guru answers reader questions about the best options for insulating a 24×30 pole barn, potential code restrictions in Victoria, MN, and Insulating a building with radiant floor heating.

DEAR POLE BARN GURU: Hello, I want to insulate my 24’x30′ pole barn located in Massachusetts. I will heat it only occasionally. I have decided due to budget and other considerations to use 2″ thick closed-cell foam in the walls. I am unsure whether to piece the foam between the bookshelf girts and place it up against the steel siding, or on the inside of the flatwise girt, leaving a 1 1/2″ gap between the foam and siding. In either case I will be sure to seal all the joints well with spray foam. I’m thinking the second option would be better to avoid trapping moisture between the foam and siding. I suppose a third option would be to install the foam on the inside of the bookshelf girts leaving a 5″ air space. This option has the benefit of eliminating the thermal break created by the girts. Which option do you recommend? DAVID in WESTFIELD

Just when you think you have everything figured out, along comes me and picks Door D.

What? There is no Door D….

Air gaps in walls are problematic, they allow moisture to gather, drafts to occur and fire to rapidly spread.

My recommendation is to completely fill this cavity with Rockwool. It does not burn, is not affected by moisture and critters will not try to live or nest in it. You will want to have a vapor barrier on interior face, between framing and wall finish.

For extended reading: https://www.hansenpolebuildings.com/2013/03/roxul-insulation/

 

DEAR POLE BARN GURU: I live on an acre within the city limits of Victoria, MN does the code allow pole barns as a detached garage? MARK in VICTORIA

DEAR MARK: A permit issuing jurisdiction cannot legally restrict a code conforming structural system, however your Planning Department may have restrictions in regards to setbacks, footprint and even allowable types of roofing and/or siding. You will want to reach out them directly: https://victoriamn.gov/government/community___economic_development/index.php (contacts and phone numbers are at left side of page).

This should prove helpful further reading: https://www.hansenpolebuildings.com/2013/01/planning-department-3/

 

DEAR POLE BARN GURU: What Options other than spray foam for insulating a pole barn ceiling up against the roof peak to keep the trusses exposed? Building has Prefabricated wood 2×6 trusses 4′ apart with wood 2×4 purlins against the metal roof. Building has no vaper barrier. Planning on doing 2 layers of insulation on the walls. First layer 2″ Foil faced EPS foam board against the girts (not between the girts) with taped seams. Second layer 3 1/2″ mineral wool. The 2 layers will fill the 5 1/2″ cavity between the 4×6 posts. Should the walls have a plastic vaper barrier on the inside after the mineral wool? Or is the first layer of EPS foam board act as a vaper barrier? Building will have radiant floor heating. I Appreciate your thoughts, Thanks! PETER in MANAHAWKIN

DEAR PETER: You have no option but closed cell spray foam applied directly to underside of roof steel, if you want to leave trusses exposed. Otherwise, you would have to provide an inch of clear airflow from eave to ridge directly below roof deck – impossible with purlins blocking this flow. A better option would be to install a ceiling (provided your trusses will support this added weight) and blow in granulated Rockwool or fiberglass (this does require vented eaves and ridge in correct proportions). Why better? You will not be heating a huge volume of space above your truss bottom chords. You should, however, still spray enough closed cell spray foam on underside of roof deck to prevent condensation (2 should do it).

Your sealed foam boards are now your vapor barrier, so you will want no interior vapor barrier. This combination, along with spray foamed roof deck, will cause your building to ‘dry’ to inside. Expect to have to mechanically dehumidify, or face mold and mildew issues.

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

Don’t Mold My Furniture

Don’t Mold My Furniture

Loyal reader RICHARD in MOBILE writes:

“Hey Guru, love your site but I can’t seem to find the answer to my question. First off I am in Mobile Al right on the gulf coast where it is hot and very humid most of the year. I recently bought a 60 x 24 x 20 tall building that I need to insulate a section of it about 40 x 24 and wall it off from the rest of the building and use a mini split in there, the reason that it will be conditioned is that I will have furniture stored in there with quilt like covers over them and I am worried about it molding. My questions are 1) do I use a radiant barrier on all roof and walls and use rigid foam board over the radiant barrier in the conditioned space area? The conditioned space will be on the ground floor and not be attached to the roof structure. 2) Can I use rigid board over radiant barriers and if so which kind of barrier? 3) or just use rigid board throughout, walls and ceilings and no radiant barrier? 4) Or what product would you suggest and the correct use and application??? Thanks in advance.”

Thank you for your kind words, much appreciated.

Before we get into your questions, some concerns:
a) Hopefully you are not ever consider storing furniture upstairs, as it is not designed for other than a fairly minimal load (certainly no greater than 40 psf – pounds per square foot);
b) Your roof has no provision to prevent condensation. There is a high probability it will literally ‘rain’ inside of your building at some point in time (get an unexpectedly cool night in winter)
c) Connections of roof purlins to trusses may be inadequate to handle high wind loads, you might consider adding Simpson Strong-Tie H-1 or similar brackets to connect purlins to trusses.

On to your questions:
Radiant barriers only “work” when they are adjacent to a perfectly sealed dead air space, so probably not a viable option. If using rigid foam board, keep in mind it is highly flammable and should be covered with at least 1/2″ (if not 5/8″) gypsum wallboard. If you place it on outside of framing, walls and ceiling will dry to inside (moisture will be trapped in your storage space). If placed on inside (and well sealed) outside moisture should stay out. There may, or may not, be a vapor barrier under your building’s concrete slab. If not, expect moisture to be passing through floor. Your mini-split may not be able to adequately remove moisture from this space.

What I would probably do….use a sealant on concrete floor. Wrap area to be conditioned with an Omnidirectional house wrap (so moisture passes out of framing). Fill cavity with Rockwool batts, place a well sealed vapor barrier on inside of framing, discuss removing moisture mechanically from area with HVAC provider.

Best of success with this.

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

When to Fill, Wall Insulation, and Gable Vents

This Wednesday the Pole Barn Guru answers reader questions about best time to fill in uneven grade, best method to insulate walls with no housewrap, and addition of gable vents to help with condensation.

DEAR POLE BARN GURU: Maybe you can give some advice on our pole barn build. Our rat board is 6ft above ground, we were told the leveling would be after structure was erected. Should we build wall with cinder blocks or just fill fill fill? CATHY in ST. LOUIS

DEAR CATHY: It would have been so much easier to fill before construction started as it is now going to be a challenge to properly compact your fill whether you have a block wall between columns or not. If you do use a block wall, it will need to have a poured footing at or below frost line and be engineered to withstand the weight of the fill being placed against it. Ultimately it is probably most economical to fill, fill, fill (make sure to have it properly compacted no less often than every six inches.

 

DEAR POLE BARN GURU: I just built a pole barn garage. The builder used double bubble under the steel roof and also blew in R38 above the steel ceiling. I will be insulating the walls myself. Unfortunately I did not add house wrap under the steel siding. Would it be an issue if I used a thin foam board between the girts properly sealed and taped to act as my WRB, installed directly against the steel. Then use R-19 fiberglass batts over the foam board for the main insulation. I already have 14 rolls of the fiberglass insulation, so I would prefer to use it vs going in a different direction. Also, should I or should I not add a 6mil vapor barrier over the fiberglass? Any help would be appreciated! GREG in SLATINGTON

DEAR GREG:  if you place properly sealed insulation boards between your wall girts, then you need to use unfaced batts with no internal vapor barrier (ideally Rockwool). Otherwise, you will be trapping moisture between two vapor barriers. If doing as you propose, it may be necessary to mechanically dehumidify your interior.

 

DEAR POLE BARN GURU: I have a 50×100 cold storage building that condensates like crazy on the ceiling. It currently has ridge vents, but no soffit vents as it does not have an overhang. I was wondering if gable vents would help to alleviate the issue and what size would be needed? JACOB in LESTER PRAIRIE

DEAR JACOB: Adding air intakes may help, but are not a guarantee of being a fix. You would need to add 1200 square inches of NFVA (Net Free Ventilating Area) in air intake, in order for your exhaust (ridge) vents to adequately function.

You should look at your source of moisture. Assuming you have a concrete slab on grade, if it does not have a vapor barrier underneath, it needs to be sealed. Make sure gutter downspouts discharge water at least 10 feet away from building. Exterior needs to be graded away from building at least 5% for this same 10 feet.

 

 

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

Plans for a 4 Plex, Romex Wiring, and Foam Board Insulation

This Wednesday the Pole Barn Guru answers reader questions about plans to build a 4 plex, running romex wiring in a post frame structure, and the installation of foam board on walls and a better method for wall insulation.

DEAR POLE BARN GURU: Hello. I’m curious if you could help me with plans to build a 4 plex. Thank you. TIM in YAKIMA

DEAR TIM: Most certainly we can. Not only do we provide floor plans, your new building investment includes full multi-page 24” x 36” engineer sealed 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!

Things Hansen Pole Buildings Does Better Than Any Other Post-Frame Building Provider

 

DEAR POLE BARN GURU: I can picture running romex wiring around the outside of the building posts when using bookshelf girts but I’m not clear on how that would be allowed as the the surface of the romex is only a little over one inch from the outside of the girt. Doesn’t that put it at risk of penetration by a siding screw or nail? Seems like it would just be easier to drill the post. As always, thanks for your wealth of knowledge and patience with self builders! RUSS in TILGHMAN

 

DEAR RUSS: Siding is in place long before you will be running wires, so there should be no reason to have a siding fastener hit a wire. Think of a hole being drilled through as being an “open knot”. Lumber grading rules refer to these as being “Unsound or Loose Knots and Holes” due to any cause.

For #2 graded lumber holes may be no less than every two feet and up to 5/8” diameter in a 2” nominal face; 7/8” in a 3” nominal face; 1-1/4” for 4”; 1-1/2” for 6”; 2” for 8” and 2-12” for 10”.

For other (higher) grades holes may be no less than every three feet and up to ½” diameter in a 2” nominal face; ¾” in a 3” nominal face; 1” for 4”; 1-1/4” for 6” and 1-1/2” for 8” and wider.

 

DEAR POLE BARN GURU: How do I install foam board insulation on the metal walls of my pole barn? DONALD in SOUTH WALES

DEAR DONALD: This would be way down on my list of ways to insulate building walls.

Why? Too difficult to get a 100% air seal.

Assuming you already own it – cut tight to fit between external girts, glue to steel siding, tape all seams to try to get an air seal. You will need to cover interior with inflammable materials as foam board cannot and should not be left exposed.

Me – I would use Rockwool batts with an interior vapor barrier

This entry was posted in Barndominium, Pole Barn Questions, Pole Barn Design, Constructing a Pole Building, Pole Barn Planning, Pole Barn Structure, Ventilation, Building Interior, Pole Barn Apartments, Insulation and tagged , , , , , , , on by .

A Basketball Court, A “Dog Trot” and Proper Insulation

This week the Pole Barn Guru answers reader questions about building a basketball court within town height restrictions, building a “dog trot” and some advice on the proper way to insulate a red iron building.

DEAR POLE BARN GURU: I have been on the pole barn Facebook group for over a year and was strongly considering that for a long time however one of the main uses I want the building for besides a workshop and storage is I’m going to build a basketball court for my son and I need the ceiling height to be at least 20 ft in the center probably closer to 25 and I know that will be challenging with a pole barn even with a scissor truss. One of the issues is the town won’t allow residential buildings over a certain height, I think 30′ and we want at least a 12/3 roof pitch so with a 50′ width we would still struggle to get the interior ceiling height we are looking for. Appreciate the info though. NICHOLAS in WESTCHESTER

DEAR NICHOLAS: We have a half-court in our post frame shouse, wish we would have gone 20′ ceilings rather than 16′. As far as heights, we can engineer and provide up to 40′ sidewalls and three stories (or 50′ and four with fire suppression sprinklers), so your heights are not a problem at all. https://www.hansenpolebuildings.com/2017/04/indoor-basketball-courts/?fbclid=IwAR3E-ZfmI-ICt-QwTZxetHfhk5GYl4bWGfPxTo1HTck-XCS4D6FCgrqFI5M

See what you can find out on your overall height issue for certain. Often they can make small exceptions without having to go through any lengthy or expensive processes. With 50′ span at 3/12 and 30′ overall height you should be able to get close to a 23′ ceiling height. An option might also be parallel chord scissor trusses. Would gain some interior height at center – lose some at sidewalls.

 

DEAR POLE BARN GURU: Have you ever built a dog trot style like this using metal buildings? Do you have pictures you can share? My husband and I really want to do this dog trot and hope to see pictures. Can you tell me what size the two structures were the you provided? Also can you provide roof pitch? Our plan is to place at least the first structure or both and build the porch in between. REEDE in STAFFORD

DEAR REEDE: Yes, we have provided dog trot home post frame buildings. https://www.hansenpolebuildings.com/2020/08/a-dog-trot-post-frame-home/

Because we provide only DIY buildings, we have only a very small percentage of our clients providing us with finished photos. We have done a broad variety of footprints, due to each building we provide being custom designed for each client’s individual wants and needs. Most often roof slopes are 4/12 as it is usually most economical and easiest for an average DIYer to work on.

Our team will gladly provide sketchups for you, for free, so you can get an idea of what your chosen plans will look like in real life. 1.866.200.9657

 

DEAR POLE BARN GURU: Hello! I keep reading on how to properly insulate on these Facebook groups and have no idea what is accurate. I’m building a red iron building and want to insulate. Metal roof and metal liner on the inside. I’m building a K building from Elgin service center in Ohio. What do you recommend?

Building is in Northwest Ohio. A gym and shop with offices. Space will be heated and cooled.

I’ve gotten a couple quotes and full foam is pretty pricy. Would you recommend house wrap and fiberglass? Or is that a really bad idea? SETH in OHIO

DEAR SETH: You are in Climate Zone 5A for commercial metal buildings requirement for ceiling is R-49 Walls R13 + R14 continuous. You could meet this with all closed cell 7″ in roof, 4″ in walls, or do a combination of 2″ of closed cell plus 10″ open cell in roof. 2″ closed/4″ open in walls. Spray foam should be applied directly to inside of steel.gymnasium

For walls you could probably Tyvek and use batts (I would recommend Rockwool) with an interior vapor barrier, although Code wants 2″ of closed cell, then you could add R-13 unfaced batts with no vapor barrier on interior. For roof, if you have no other source of condensation control, you need at least 2″ of closed cell spray foam directly to roof steel.

 

 

This entry was posted in Professional Engineer, Pole Barn Homes, Pole Barn Questions, Pole Barn Heating, Pole Barn Design, Barndominium, Pole Barn Planning, Trusses, Ventilation, Building Interior, Budget and tagged , , , , , , on by .

Help! Help! PEMB Insulation/Ventilation

Help! Help! PEMB Insulation/Ventilation

Reader JD in ANDERSON writes:

“Dear Guru, I am finally ready to build my dream shop, rec space. Slab is poured. Will be 30x50x16 with (2) insulated panel 12×14 overhead doors in one of the 30ft ends. My question is about ventilation / insulation. To meet my budget, I chose a cold formed steel framed building with vertical 24 gauge steel roof & siding. I want the building to be “livable” & plan to install (2) mini split heat pumps for heating & cooling. I’m in southern SC so no real extreme temps. The building co wants to insulate with Prodex sandwiched between the siding & frame. There is no finished ceiling or attic space & there is a ridge vent from end to end. When asked about how to keep heat in during the winter due to the ridge vent, they tell me “that’s not something we worry about”. Not sure what that means but I assume heat rises & will vent out the ridge making it impossible to heat. Down the rabbit hole I went. First thing I found was everyone bashing Prodex. Ok, I figure the majority of steel buildings have been insulated with faced fiberglass batt since the beginning of time, I’ll do that. Then I read about moisture & mold caused by the batt. Ok, spray foam then, perfect! Then I’m told it voids the building warranty. My head hurts! I have just about decided to spray foam anyway with 2in of close cell on the walls & the roof. But what about ventilation? The spray foam folks say that with their product there is no need to ventilation in the building at all. They say no need for the ridge vent & the closed cell will be sprayed right over it to seal it off. If I don’t use the Prodex, the building co says there will be no heat transfer break between the siding & framing. Siding will be screwed straight to metal frames. There will also be no radiant reflective barrier or vapor barrier. The spray foam place says I don’t need either. They say the miraculous closed cell foam will handle it all. Basically they are telling me that the inside of my building will be a huge styrofoam beer cooler & will need no ventilation to control moisture & there will be no heat transfer at all. This is a HUGE investment & I can only do it once. It has to be right the first time. Please help!!!! Thanks so very much!!!”

There is sadly so much bad information available.

Prodex (or any other reflective radiant barrier) is not insulation. If properly sealed, it can be an effective vapor barrier. If you use it and vent ridge, then you are correct – out ridge goes your heat.

Fiberglass is not a cause of mold and mildew, it is a symptom of a building without adequate methods of removing excess moisture.

Closed cell spray foam – ask to see a written warranty copy showing building or even steel cladding with closed cell spray foam applied will void it. Chances are very small one exists.

What would I do?

Closed cell spray foam at least two inches thick sprayed directly on inside of steel roofing and siding. No ridge vent. Have a qualified HVAC provider design a system to mechanically remove excess humidity. You will need to fire protect inside face of closed cell spray foam. This might be an option https://www.hansenpolebuildings.com/2019/08/fire-rated-spray-foam-insulation/. Intumescent paint may also be a possibility. If you want higher than R-14, you could go with thicker closed cell, add open cell to inside face of closed cell, or add unfaced batts (my preference would be rockwool)

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

Lots of Bad Advice for Retrofitting Roof Insulation

Lots of Bad Advice for Retrofitting Roof Insulation

Reader DAVE in GALES CREEK writes:

“I’m desperate, or I wouldn’t be bugging you with this. We have a 38×48 pole barn / shop with concrete pad that was on our property when we bought it. There are 4 sections between trusses, and one of those has been walled off as a work area. I really need to insulate the ceiling / roof of this area. For heating purposes and some extra sound absorption. The roof has 2×6 rafters running parallel to the length of the building – no soffits or vents. The existing insulation is vinyl backed fiberglass between the rafters and metal roofing. It does very well for what it is, no problems. I’ve had so many people tell me EVERYTHING I learn is wrong – it’s cost us dearly over the last few years being paralyzed with fear that we might do it wrong and regret it. How would you do this? Most say to tear out the vinyl back fiberglass, fill the rafter cavities with Rock Wool (or fiberglass), an interior vapor barrier and then cover the ceiling with PVC roofing or tin. Others say to leave the fiberglass vinyl backing in place,( Which I prefer) use Rock Wool, but leave an air gap so there will be air flow into the rest of the shop to avoid condensation on the vinyl backing. Like a mini attic space to avoid creating a double vapor barrier? I would use spray foam, but without getting into it, it’s not an option. I’d have to use foam board, rock wool or FB insulation. Could you please help us? Any advice would be so greatly appreciated. We’re losing our shirts on this project taking so long. Anything would be helpful at this point. I’d be glad to send diagrams and photos if need be? Thank you very much for your time either way.”

Mike the Pole Barn Guru answers:

While I am not a fan of vinyl backed fiberglass (aka metal building insulation), provided seams are sealed and facing is not punctured, it does provide a condensation control.

If you were to tear out what you have (would be a painfully tedious project), your only option would be closed cell spray foam directly to roof steel. Why? Because, Building Codes require an inch of clear space between insulation and roof deck from eave-to-ridge. As your building’s roof purlins prevent this from happening, any sort of batt insulation in plane of roof would not be an option.

Provided your trusses are capable of carrying added weight of a ceiling, or you can support a ceiling off of 38 foot walls on each side of this bay, your best option is to blow in insulation directly above said ceiling. First choice would be granulated Rockwool (it is not affected by moisture and does not degrade with time), second would be fiberglass. If using steel panels for a ceiling, do not blow cellulose on top of it, as chemicals in it are likely to react negatively with steel.

Leave attic area above ceiling open to balance of building, so as not to create an unventilated dead air space. Otherwise, you will need to add gable vents (as an air intake) and vent the ridge.

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Insulation, Truss Spans, and Pit Material

Today’s Ask the Pole Barn Guru discusses reader questions about an option to layer insulation between purlins, the actual building width for 36′ trusses, and the recommendation against the use pit material when performing site prep.

DEAR POLE BARN GURU: Hi, I have the traditional roll type insulation with the white backing. My question is if I’m able to add more insulation between the purlins on top of the existing insulation for added r value and what type would you recommend if so? Thanks OWEN in VIVIAN

Metal Shop BuildingDEAR OWEN: Metal Building Insulation (MBI) is not my favorite design solution for post frame insulation (read more here: https://www.hansenpolebuildings.com/2011/11/metal-building-insulation/).

You can add more insulation to interior of what you have, without having to perforate white vinyl of you MBI. I would recommend adding unfaced Rockwool, as it is not affected by moisture and has a relatively high R value per inch of thickness compared to fiberglass or cellulose. Do not add another interior vapor barrier, as this would allow for moisture to become trapped between two vapor barriers.

 

DEAR POLE BARN GURU: You really are a wealth of knowledge.  I’ve been watching your Youtube videos as well, very helpful.

I’m intrigued by your pole barn kits, and I had just one more question about raised heel trusses:

It’s my understanding that post spans are actually building widths minus 3 inches.  So for a 36 foot building, the span between posts is 35’ 9”, correct?  If that’s the case, are raised heel truss lengths in this example also 35’ 9 to the edge of the post?  Or the full 36’, with the eave skirt board resting under the additional 1.5 inches of the bottom chord length?

Thanks again for your time!!! MATT in CHENEY

DEAR MATT: Our buildings (as are most Pacific Northwest Buildings) measure 36 feet from outside of column to outside of column. This allows for 12 sheets of steel plus the lap on the 12th piece (covering 36′ 1-1/2″ roughly) to be installed without having to rip the last steel panel lengthwise. Pressure preservative treated splash planks, headers, etc. will be applied to exterior faces of columns, giving a framed finished width of 36’3″.

 

DEAR POLE BARN GURU: Hi. In your building manual it notes not to use pit material on the building pad. If the site is leveled, I’m not sure what the function of any modified is or why no pit material in specific. We’ll be doing a slab at some point and common practice would be to put down some clean 3/4″ so if it’s beneficial to have stone on the building pad would it be more cost efficient to just put the clean stone down to start with? Thanks. KEVIN in WEST CALN

DEAR KEVIN: #1 reason to not use pit run is it is difficult to auger holes through.

#2 because it is round, it does not compact well

#3 It creates voids allowing for free flow of liquid water beneath slab

You do want to allow for two to six inches of clean sand or sandy gravel compacted immediately below your under slab vapor barrier.

 

This entry was posted in Trusses, Concrete, Columns, Insulation, Pole Barn Questions, Pole Barn Design, Constructing a Pole Building, Pole Building How To Guides and tagged , , , , , on by .

Purlin Spacing, Wall Insulation, and Roof Sheathing

This week the Pole Barn Guru answers reader questions about purlin spacing for 2×8 that span 17 feet, wall insulation recommendations, and if roof sheathing is needed for a new shop.

DEAR POLE BARN GURU: I need to span 17 feet with 2×8 purlins. Do I need to go 12 inch on center, or can I double 2x8s 24″ on center? Will deck with 7/16 OSB and install standing seam metal roof. BRAD in SPARTA

DEAR BRAD: IRC Rafter span tables are available online here: https://codes.iccsafe.org/content/IRC2021P2/chapter-8-roof-ceiling-construction

Scroll down to Table 802.4.1(1) (this would be for a minimal snow load).

Assuming 2×8 #2 Southern Pine 24″ on center will span only 13’1″ (even 2×10 #2 will only span 16’6″).

Going to a spacing of 16″ on center 2×8 #2 Southern Pine will span 17’1″.

 

DEAR POLE BARN GURU: Hello, I am looking to insulate the walls of my pole barn and plan on putting up vapor barrier. I insulated the ceiling last year and used Tyvek® basically to hold up the insulation as I can’t afford the steel yet. My question is should I also put up a vapor barrier on the ceiling? Thanks in advance, I appreciate the guidance as this is not my expertise. CHAD in GENESEO

DEAR CHAD: Henry County is Climate Zone 5A.

For your walls, I would recommend unfaced Rockwool either R-30 with a well-sealed interior vapor barrier or R-20 with R-5 well sealed continuous insulation boards on the interior (Comfortboard® 80 or EPS).

As you have under 8000 heating degree days, a ceiling vapor barrier would not be required. Hopefully your attic insulation is Rockwool as fiberglass is affected by moisture and loses R value when exterior temperatures drop. Make sure your attic space is properly ventilated (https://www.hansenpolebuildings.com/2018/03/adequate-eave-ridge-ventilation/).

 

DEAR POLE BARN GURU: Hello, I am building a 36x50x12 shop with 5:12 roof pitch, that will be conditioned space. The plan is to build out the interior with 2 small bedrooms and a bath then the rest open floor. I am putting in a ceiling at 12′ and will insulate the walls and ceiling leaving the roof uninsulated. Building is located in South Central Texas near La Grange. Does the roof need sheathing and felt or can I just lay the metal roof directly on the purlins? What about adding house wrap to entire building, walls and roof? Being in Texas, heat is biggest factor and with the a/c pumping inside I want to keep attic space vented correctly to keep moisture from building up. I plan to have large soffits to allow for soffit venting then ridge vent on roof. One of my biggest concerns is keeping out all the elements, including creep crawly bugs and concerned the garage doors will be source intrusions. It is my understanding that a sectional garage door is best for keeping out the elements vs roll up type. Can a garage door be truly sealed from all elements including bugs from crawling in? STEVEN in SUGAR LAND

DEAR STEVEN: Roof probably does not need to be sheathed unless your design wind speed is 140 mph or greater (Code requirement) or your engineer specified it. Do NOT housewrap roof, order roof steel with an Integral Condensation Control factory applied. Order raised heel trusses so you can have full attic insulation depth from wall-to-wall. While a sectional garage door is best, there is never a 100% guarantee of keeping crawling critters out – because you are going to open door at some point.

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

Help! My Barndominium Vaulted Ceiling Drips

Help – My Barndominium Vaulted Ceiling Drips

Reader HOMER in PIEDMONT writes:

“I called in today and was referenced to send an email – 

I have come across your website and have gained a vast amount of knowledge – I was hoping to get some more information on my situation – I also understand that you actual don’t sell insulation and that any advice you give me might not benefit your business – I am willing pay a consulting fee if you like or if i can purchase any products through your company that will help me get out of this pickle i will be more than happy to – 

So my situation (the pickle) 

I built a 30×60 barndominium with vaulted ceiling (the purlins on top are 8″) i used about 1/2″ to 1″ of closed cell spray foam all over it then laid the typical pink batting insulation in it – the issue I am having is I am in Oklahoma – on a morning of a cold night – when the sun comes out it heats the metal roof up and creates condensation – hence a ceiling that rains throughout the day – it seems to happen closer to the peek more than the bottom portion of the ceiling 

I have tried pulling some of the batting insulation out of the middle section to help create more air space – it did seem to help a bit but still saw condensation on the spray foam insulation – when i removed my test panel (also i used 3/8 bead board for my interior sheeting) 

On the peak of the roof I didn’t use the foam vent ridge cap but filled it in with spray foam (I was going for air tight) which might be more of the issue 

I truly am sorry to bother you with this issue and any help or direction would be greatly appreciated – please reach out via email or phone and I am sorry if I didn’t give enough detail to paint the picture that I am facing.”

Mike the Pole Barn Guru says;

Thank you for reaching out to us. Our goal is to assist our clients from making crucial (and often costly) errors they will regret forever. While your circumstance is crucial, it can be rectified.

According to Johns Manville, a minimum of 1-1/2″ of closed cell spray foam is required in order to provide an adequate air and vapor barrier (we have always recommended two inches, as we feel it is better to be safe than sorry). Right now, the underside of your closed cell spray foam is cool enough on those cold mornings so warm moist air rising inside meets it and condenses. This is more pronounced as you approach interior peak due to warm air rising.

If it was my own roof – I would remove all fiberglass roof plane insulation, increase thickness of closed cell spray foam to at least two inches, then fill balance of 2×8 cavity with either open cell spray foam or rock wool batts (rock wool is not affected by moisture and does not lose R value during cold temperatures).

Only other possible solution (have not tried, so is only hypothetical) would be to mechanically dehumidify the interior of your barndominium to a degree low enough to eliminate your challenge. This would probably need to be under 20% relative humidity – so low as to become uncomfortable to live in (Dry, itchy skin & eyes) and causing shrinkage of wood in floors, cabinets, doors and furniture.

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

Does My Pole Barn Need a Vapor Barrier?

Does My Pole Barn Need a Vapor Barrier Above the Metal Ceiling?

Reader DAVID in BALDWINSVILLE writes:

“I have a new pole barn with bubble vapor barrier under roof metal. I am installing a metal ceiling with R-38 cellulose in the attic. Do I need a vapor barrier above the metal ceiling? The barn will be heated somewhat in winter.”

From Mike the Pole Barn Guru:

Kudos to you for recognizing bubble wrap products advertised as ‘insulation’ are, at best, a good vapor barrier if properly sealed!

My son Brent is working on his doctorate at UMass Amherst, so I utilized Building and Construction Technology information from their Department of Environmental Conservation in penning this response.

My concern is with blowing in cellulose above a steel ceiling. From UMass:

“Wet insulation of any stripe is bad. But cellulose is hygroscopic. It’s able to soak and hold liquid water. Undetected leaks can wet cellulose causing it to sag within framing cavities. Water leaks can compress the blanket of fiber and in extreme cases, can create a void space, degrading its thermal value. Another concern is that chemicals used to protect cellulose from fire make it potentially corrosive in wet environments. Tests conducted by the Oak Ridge National Laboratory show chemical treatments used to treat cellulose can cause metal fasteners, plumbing pipes and electrical wires to corrode if left in contact with wet, treated cellulose insulation for extended periods of time. “

I’d much prefer to see you blowing in rockwool as it remains unaffected by moisture. Last thing you want is to have damp cellulose insulation chemicals eating holes in your ceiling.

According to building scientist and founding principal of Building Science Corporation Joe Lstiburek, “Plastic vapor barriers should only be installed in vented attics in climates with more than 8,000 heating degree days.”

As your site has under 8000 heating degree days a year, you should not have a ceiling vapor barrier. You do need to ensure your newly created non-conditioned dead attic space is adequately ventilated at eave and ridge (https://www.hansenpolebuildings.com/2018/03/adequate-eave-ridge-ventilation/).

For extended reading on heating degree days, please see: https://www.hansenpolebuildings.com/2022/11/what-is-degree-day/

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

Insulation Options for an Idaho Barndominium

Insulation Options for an Idaho Mountain Post Frame Barndominium

Loyal reader LORISTON in NAMPA writes:

“We are in the initial phase of preparing for our residential post frame home and are excited to partner with Hansen Buildings when ready. Thank you for all the amazing information and supporting your clients. Question: I am targeting a highly efficient design, with >r-40 walls and >r-60 roof. There is a lot that I do not know and humble to learn from others. My mechanical engineering background helps. I would like your advice on a wall and roof design that meets my targeted R-values incorporating (from outside to inside) metal siding, >3/4″ rain screen, rock wool >2″ external insulation, Zip insulated r sheathing for WRB and thermal break/R-value increase, laminated Timber Tech glulam columns with bookshelf / commercial girts, closed cell spray foam internal insulation around 3″ thickness, fill remaining thickness from spray foam to inside edge column with insulation (recommendation would be helpful on type of insulation), internal insulation on inside of wall for thermal break if needed or helps, with final residential area having 5/8″ sheetrock and shop area having metal inside finish. We have not solved how to create a space for utilities on the outside wall as we would prefer to run them on inside of columns or thermal break insulation. We are contemplating internal framed 2×4 walls spaced away from post frame wall to create a space for utilities. No water will be run on external walls, only power, low voltage, gas, telephone as reference. Suggestion on how to run utilities with this highly efficient wall design would be appreciated. Roof is similar to wall, just horizontal with >r-60 performance, as we are targeting a conditioned attic space. Roof exception may be a second zip sheathing layer over the insulation (under rain screen/standing seam metal) but to be determined. Climate Zone 6 region in the Idaho mountains for reference. Post frame columns and wall will be on a full foundation wall with thickness based on wall design. Performance is priority over cost, targeting an air tight and efficient living space. Your experience and practical approach are greatly appreciated. Best regards and thank you.”

Mike the Pole Barn Guru writes:

Thank you for your very kind words, they are greatly appreciated.

Rather than add an expensive and structurally unnecessary concrete foundation wall, I would recommend embedded properly pressure preservative treated wall columns (as my first choice), columns above grade set into wet set brackets on concrete piers as my second. Either of these can be insulated using R-10 EPS (Extruded Polystyrene) insulation boards. I would run them on the inside of the splash plank, with the top even with the top of the slab, extending down two feet, then outward horizontally two feet.

In Climate Zone 6, I normally would not look towards spray foam as my go to choice, however conditioning your attic and your desire for air tightness come into play, so here goes:

Walls (out-to-in): Steel siding over 2×8 bookshelf girts; 4″ of closed cell spray foam applied directly to inside of wall steel and balance of cavity with either open cell spray foam or rock wool (rock wool being my preference). No internal vapor barrier or continuous interior insulation boards as we want walls to dry to interior, without trapping moisture in the wall cavity.

Roof (out-to-in): Standing seam steel over 30# felt or synthetic ice & water shield (second preferred) over 5/8″ CDX plywood. Zip sheeting is OSB and screws just do not hold well into OSB. We can specify 2×12 roof purlins in order to get a deep cavity for insulation. Closed cell spray foam 5-3/4″ (R-40) plus R23 rock wool (5-1/2″).

This combination will require mechanical removal of humidity.

My normal recommendations would be:

Walls (out-to-in): Steel siding over a Weather Resistant Barrier, over 2×8 bookshelf girts. Fill the cavity with two layers of R15 rock wool. Add R-10 EPS well-sealed on interior. This wall will now dry to the outside.

Roof (out-to-in): Through screwed steel with an Integral Condensation Control factory applied, or standing seam steel over 30# felt or synthetic ice & water shield (second preferred) over 5/8″ CDX plywood. Roof trusses with 22″ raised heels, vent eave and ridge. Blow in R-60 on top of ceiling. This eliminates the expense of heating/cooling a dead attic space.

In either instance, I would have no fears or concerns about running non-plumbing utilities within your wall insulation cavity.

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

How to Insulate a Post Frame Shop

How to Insulate a Post Frame Shop When No Advance Considerations Were Made

I encourage clients to give some serious advance consideration when erecting new post frame (pole) buildings to any eventuality of future climate control and a need for insulation.

Reader MAC in MILLVILLE writes:

“40 x 30 want to insulate. It will be used as a storage/workshop. I included pictures so you can see what I have. What’s the best way to insulate? I plan on doing metal ceiling liner and most likely plywood on the walls. There is no vapor barrier under the concrete either. I do have a vented ridge and soffit. I hope I provided enough information to be able to answer my question.”

Start by sealing your concrete floor – as this is going to be a moisture source you do not want inside of your new building.

Roof/ceiling – no provision has been made to prevent condensation from happening beneath your roof steel. Sadly I see this occur far too often, as builders, kit providers and local lumberyards just lack knowledge needed to be able to educate and make best recommendations to their clients. You could either (a) remove roof steel, add a method of condensation control (such as a Reflective Radiant Barrier or sheathing such as OSB or plywood with either 30# felt or a synthetic ice and water shield) and reinstall steel using new, large diameter screws. This is highly labor intensive and your roof may not have been designed to support the weight of adding sheathing.

Best solution will be to have two inches of closed cell spray foam applied to the underside of roof steel at roughly two dollars a square foot. Not an inexpensive solution when its need could have been prevented with better advice up front.

Cumberland County is in Climate Zone 4A, as such you should have a minimum of R-49 ceilings and R-20 walls. Perimeter of your slab should be insulated two feet deep with R-10.

I would dig a trench two feet deep around your building, up tight to its pressure preservative treated splash plank and install R-10 rigid board XPS insulation from the height of the top of the slab down two feet. Install a metal, cement board, or cellular PVC panel to conceal any insulation portion left exposed above grade. If cement board is used, it should be a type not reinforced with wood fibers. Install a metal cap as an insect guard to conceal the top horizontal edge of both insulation board and closure panel. Seal cap to splash plank with mastic.

Once you have a ceiling liner in place, blow in R-49 or greater thickness of fiberglass insulation.

For walls, I normally like to see a Weather Resistant Barrier (like Tyvek) between framing and siding. As you do not have this, I would use R-21 unfaced Rockwool stone wool insulation, as it is not affected by moisture. Place a well-sealed 6mil clear plastic vapor barrier over the inside of insulation prior to placing plywood on walls.

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

Insulated Bookshelf Wall Girts

While we United States residents like to think of ourselves as perhaps the center of our universe, post frame construction appears world wide.

Reader JONATHAN in HALIFAX picked Alabama as his state when he filled out his online request for information when he wrote:

“What insulation do you suggest between bookshelves of wall?”

With so many post frame buildings being used for residences, commercial buildings, shop/houses and barndominiums, properly addressing how to insulate has become of utmost importance.

I am going to take a stab and guess your Halifax is in Nova Scotia, rather than Alabama. My lovely bride and I made a stop there on a cruise from New York City a few years ago – beautiful area (and I got a Harley-Davidson T shirt).

If so, you are in what would be an equivalent to our IECC (International Energy Conservation Code) Climate Zone 7. For wood frame walls, this would require an R-20+5 or R-15+10, where your plus value is for continuous insulation.While continuous insulation is most often usually on exterior of framing, Martin Holladay – editor of Green Building Advisor feels confident in it working as well on inside of framing. Given this, I would put a Weather Resistant Barrier (https://www.hansenpolebuildings.com/2016/01/determining-the-most-effective-building-weather-resistant-barrier-part-1/) between wall framing (bookshelf wall girts) and siding, then fill your cavity with rock wool (as it is not negatively affected by moisture), then use rigid foam insulation inside of your framing. You can glue these sheets to your framing (bookshelf girts) to eliminate any thermal bridging from fasteners and then glue your interior finish to it. Make sure to tightly seal your rigid foam boards and to caulk along the bottom of exterior walls to get a good seal. Built in this fashion, your walls will ‘dry’ to the outside, reducing the need for dehumidifying inside.

Of course you will want to get approval from your local permit issuing jurisdiction before moving forward.

For extended reading on rock wool insulation please see https://www.hansenpolebuildings.com/2013/03/roxul-insulation/

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