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Insulating Pole Barn Scissor Trusses Reader

Insulating Pole Barn Scissor Trusses Reader

ROB in OAK HARBOR writes:

“What is the best way to insulate the ceiling/attic of a pole barn with scissor trusses? There is a approximate 4 to 6 foot gap between the underneath side of the roof deck and the peak of the scissor truss. On the wall ends there is hardly any space at all. They are not raised scissor trusses. Thank you!”

Here is where lack of planning by your building provider has left you in an uncomfortable situation. Raised heel trusses would have made for such an easy design solution.

For extended reading on raised heel trusses, please see: https://www.hansenpolebuildings.com/2012/07/raised-heel-trusses/

Architect Terry Smith of TDSA Architecture in Washington state recently contacted NAIMA with a question about how to properly insulate scissor roof trusses. Terry rightly pointed out insulation is intended to be most effective when uniformly applied or layered to cover full extent of space being insulated. But there are instances, such as narrow areas near top plate of scissor trusses and sloped ceilings, where this is not possible.

Terry could not find any guidance in his state’s building energy code to address how to properly insulate narrow areas near top plate of scissor trusses where this area is very narrow. Similarly, fully insulating sloped ceilings to meet code requirements can be tricky. There is no code specific guidance to specifically how to do either properly.

General Guidance on Insulating Narrow Areas

Generally, R-60 is code requirement for Ottawa county, you can install full height R-60 for areas where there are no height constraints, and then fill areas having constrained heights (but making sure to install eave baffles). Alternatively, you could have a raised heel truss and install a minimum of R-49 across entire attic floor per 2021 IECC R402.2.1 (similar provisions exist in other IECC versions).

Guidance for Sloped Ceilings

Insulation Institute spoke with Johns Manville Research Manager and Engineer Francis (JR) Babineau regarding whether state codes provide specific guidance on insulating sloped ceilings. After conducting his own search for answers from state building energy code guidelines, J.R. noted only written information he found relative to insulating sloped ceilings was from California:

“If the ceiling is sloped (for instance, with scissor trusses), loose fill insulation can be used as long as the slope of the ceiling is no more than 4:12. If the ceiling slope is greater than 4:12, loose fill should be used only if the insulation manufacturer will certify the installation for the slope of the ceiling.”

See reference link here: https://energycodeace.com/site/custom/public/reference-ace-2019/index.html#!Documents/35insulationproducts.htm

Bottom line: insulation manufacturer must certify installation for ceiling slope. But is this happening or do code officials simply sign off on insulation presence – regardless of whether it is or can be installed at required thickness given slope?

When Codes Do Not Specify

While state building energy codes can provide prescriptive guidance, properly insulating sloped ceilings and scissor trusses – appear to be areas where additional guidance would help clarify intended code requirement is met. Prescriptive guideline absences could leave much to individual interpretation and put onus on manufacturers to address a problem avoided with proper guidance from state building energy codes.

For your building, I will assume you have properly vented soffits and ridge. In area closest to sidewalls, where trusses have minimal height, I would install rigid insulation boards at exterior roof slope pitch, allowing one inch of clear air flow above. Rigid insulation should be extended towards peak until reaching a region where full blown in insulation depth can be achieved.

This entry was posted in Pole Barn Design, Building Overhangs, Pole Barn Heating, Roofing Materials, Post Frame Home, Pole Barn Planning, Barndominium, Trusses, Ventilation, Building Interior, Budget, Insulation and tagged , , , , , on by .

To Double-Up Trusses, Existing Bracket Use, and Ceiling Insulation

This Wednesday the Pole barn Guru answers reader questions about the need to double up trusses on a 24×36 with 2×6 trusses 12′ OC, use of existing brackets in a stem wall for a post frame home, and best method of ceiling insulation with “double bubble” on roof.

DEAR POLE BARN GURU: Building pole barn 24’x36′ with 2″x6″ trusses 12′ OC. Do I need to double up the trusses or will a single do? GARY in KANAB

nailing trussesDEAR GARY: While it may be possible to have single trusses designed to support loads adequately on 12 foot centers, we have always utilized a double truss system for interior clear spans, with a single truss on each end.

Why? To begin with, probability of two trusses, physically connected to each other, having an exact identical weak point would be infinitesimally small. This sort of redundancy minimizes possibilities of a failure, even with loads far in excess of original design. Double trusses also require far less bracing than do single trusses.

If you have not yet ordered your building, our team would certainly like to discuss it further, as we have provided hundreds of fully engineered post-frame buildings to our clients in Utah.

 

DEAR POLE BARN GURU: There is an existing stem wall foundation (only a few years old) on the property we recently purchased. Obviously we would like to utilize the existing stem wall. It seems as if it was built with a post frame building in mind because there are brackets already anchored in. The stem wall is a 50×70 foot rectangle, though we do not want to build a 3500 sqf home. Can we build a post frame home on part of the stem wall (utilizing the unused portions as a porch perhaps?) and would this approach even make sense? ANDY in BURLEY

DEAR ANDY: Like you, I hate to waste anything seemingly of value. It may very well be possible to utilize your existing foundation – provided it passed previous inspections from your Building Department. If not, it may be necessary to have a local engineer do an inspection to determine adequacy. From our end, we would need to know specifics of existing brackets (as well as their spacing), as they may be inadequate to attach to.

 

DEAR POLE BARN GURU: I have a 30 x 40 pole barn I use for a shop and office with double bubble insulation between the purlins and the steel roof. The roof pitch is 4:12 and ceilings are 12′ high. I would like to use blown in cellulose over a steel panel ceiling. Do I need a vapor barrier between the cellulose and the coated steel ceiling panels if I maintain good air flow between the eave vents and the ridge vent? Thanks in advance for the advice. DENNIS in WASHINGTON

DEAR DENNIS: Fire retardant chemicals in cellulose insulation react negatively with steel, if any moisture happens to become present. Due to this, and cellulose being relatively heavy, you might want to consider blown in fiberglass (although difficult to find, granulated Rockwool would be an even better choice, as it is unaffected by moisture). If you do determine cellulose is your best fit, you will want to have a vapor barrier to keep it out of contact with your steel ceiling panels.

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

Footing Diameter, Non-Ground Contact Columns, and Ceiling Insulation

This Wednesday the Pole Barn Guru answers reader questions about the required footing diameter for a 20’x24′ pole barn garage, use of non-ground contact columns on a concrete stem wall or thickened edge, and Insulating a cathedral ceiling in a barndominium.

DEAR POLE BARN GURU: I am looking to build a 20ft x 24ft pole barn garage. The footings are going to be drilled and filled with concrete now, with the structure being completed at a future date. My city engineer requires 30″ deep footings. He was not able to say for sure what diameter footing I needed to drill. Do you have any insight to what diameter footing I should expect to need for this size structure? JOE in CINCINNATI

DEAR JOE: Ultimately required diameter will depend upon soil bearing capacity and imposed loads. If you are single story, chances are good an engineer would specify 18 inch diameter.

 

DEAR POLE BARN GURU: I was fortunate to have acquired enough columns for a building. My question as these are not ground contact columns and I prefer at this time to not pour a concrete floor is it allowable to pour a perimeter of concrete ( 2’x2′,3’x2′?) thickened edge if you will and set the columns to keep them off the ground? I was thinking partially setting rebar perpendicular in the concrete leaving 1-2′ protruding towards the buildings center to tie a future slab possibility into what would be the existing edge ( foundation). This is a cost driven situation as you may have already surmised. Really appreciate your knowledge and time. RICK in TWO RIVERS

DEAR RICK: To save further on costs, you can pour concrete piers to support engineered wet-set brackets. This would be much simpler than pouring a concrete perimeter. Bottom of piers should be at or below frost line. https://www.hansenpolebuildings.com/2019/05/sturdi-wall-plus-concrete-brackets/

 

DEAR POLE BARN GURU: Insulating a cathedral ceiling in a barndominium. It is house wrapped and single bubble beneath the metal roof panels. Girts and purlins are on 2 ft centers. Was planning on using Rockwool and Siga Majrex with the appropriate air gap. Building is vented through soffit on all sides. Also planning on using soffit baffles( and should I take them to the peak) , along with plastic vapor barrier above stone before concrete. Is there a better way, other than spray foam, and would that be in the ceiling over top of the single bubble also? Thanks. CHAD in DILLINER

DEAR CHAD: Thank you for the photos. You need to seal any venting coming in from endwalls. This can be done by placing 2×4 blocking flat between purlins on top of end truss. Install baffles between trusses and run them “uphill” to beyond depth of your insulation to be blown in. Do not use a vapor barrier between ceiling finish and truss bottom chords. Ideally blow in granulated Rockwool above ceiling (second choice would be fiberglass).

This entry was posted in Ventilation, Concrete, Lumber, Building Interior, Insulation, Pole Barn Questions, Budget, Pole Barn Design, Professional Engineer, Constructing a Pole Building, Columns, Pole Barn Homes, Trusses, Barndominium and tagged , , , , , , , , , on by .

A BONUS PBG for Friday May, 24th — Alternative Siding, Basements, and Purlin Size

A BONUS PBG for Friday May, 24th — Alternative Siding, Basements, and Purlin Size

DEAR POLE BARN GURU: In towns that disapprove of houses with rib steel siding, can traditional OSB sheathing on the bookshelf girts w/ vinyl cladding be substituted? Material prices seem similar and no huge difference in labor seems probable. But, will the difference change the engineering specs due to racking and deflection, etc? I.E.: could that change the bookshelf girts size or spacing? How thick would the OSB need to be? What nailing would be needed? BRIAN in LEROY

DEAR BRIAN: While pre-painted ribbed steel siding is the most durable and cost effective siding available, some jurisdictions just do not ‘get it’ and demand (as is their right) alternative sidings. When we engineer using commercial bookshelf wall girts, we limit deflection to what sheetrock will withstand, so they are effective with any type of external siding materials. No changes to structural system will need to be made, other than vertical blocking between wall girts every 4′ (in order to provide a nailing surface for edges of OSB). If you use vinyl siding, then 7/16″ OSB and a Weather Resistant barrier will be necessary. Typical nailing will be 8d common nails at 3″ on center along panel edges.

 

DEAR POLE BARN GURU: Can a pole barn building have a basement? CLARK in HILLSBORO

DEAR CLARK: Absolutely! We can even engineer it using a permanent wood foundation, saving you thousands of dollars as compared to a concrete foundation. https://www.hansenpolebuildings.com/2020/02/barndominium-on-a-daylight-basement/

 

DEAR POLE BARN GURU: I’m building a 36x64x16 8′ truss spacing . We want exposed truss and ceiling cavity without the use of drop ceiling or blown in bat. My question is it smart to use 2×6 purlins instead of 2×4 to allow for room for faced 6″ insulation to get a R19 value, besides spray foam what are some other options. Thanks. ZACH in LAUREL

DEAR ZACH: While it is smart to use 2×6 purlins, using batt insulation between your purlins will result in nothing but long term problems. Your only real answer is closed cell spray foam https://www.hansenpolebuildings.com/2023/10/properly-insulating-between-roof-purlins/

This entry was posted in Pole Barn Questions, Pole Barn Design, Budget, Building Styles and Designs, Building Department, Lofts, Roofing Materials, Pole Barn Homes, Pole Barn Planning, Pole Barn Heating, Trusses, Ventilation, Lumber, Alternate Siding, Barndominium, Insulation, Building Interior and tagged , , , , , , , on by .

To Vapor Barrier a Ceiling, or Not to Vapor Barrier a Ceiling.

To Vapor Barrier a Ceiling, or Not to Vapor Barrier a Ceiling.

Reader RAY in LAPINE writes:

“Hello, I live in Central Oregon, in climate zone #5. We are located in the High Desert at 4400 ft. The climate is dry with low humidity, occasional snow and cold in the winter. The summer temps are around 80 degrees, with large day to night temperature swings. Our heating hours per year are listed at approximately 7500+ per year. I am wanting to install 2×6 stringers, along with blow in insulation, but so many things are conflicting in my opinion, regarding my building when it comes to vapor barrier, no vapor barrier, heating hours per year, ventilation, etc., so I need your professional opinion. I have a 24×48 Pole barn, with double trusses, rated for 7 pound on the bottom cord. The truss bottoms are at 16ft off the concrete floor and are spaced 12 feet on center. The metal roof panels have dripstop that was factory installed. The walls have house wrap, behind bookshelf girts and was installed when the building was erected. The building has a continuous vented ridge, no soffit vents and is heated using a new, large, catalytic wood stove. I want to heat the building approximately 5-10 days a month, 8 to 10 hours a day for approximately 4 months of the year. So my question is, because of the drip stop panel coating and local heating hours, do I need any form of vapor barrier at the ceiling level or on the face of the purlins to avoid condensation issues??? I was originally going to install 10 mil, fire retardant, mesh reinforced poly on the bottom of the 2×6 stringers/trusses, wall to wall and blow insulation on top of the poly, then install 1/2 plywood painted white. Then I read not to use poly or a vapor barrier under 8000 heating hrs. After reading that, I thought I would use a air permeable product like ADO Insulweb, attached it to the bottom of the 2×6 stringers/trusses and blow insulation on top of that to R38, then install the plywood as stated before. Based on what I’ve read, it sounds like I need to install gable vents to the recommended ventilation ratio. Please provide me with your input and advice. Thank you.”

Spent many a winter day on Mount Bachelor’s slopes back when I lived in Oregon (even 4th of July one year), so am familiar with your turf (my step-brothers also live in your immediate area).

Based upon your information, I would install ceiling plywood and then blow in insulation directly on top of it. Paint your plywood after it is installed and this should be a sufficient vapor retarder. You will need to add gable vents, in lower half of your attic space. For a 24′ x 48′ building, you will need at least 139 square inches of NFVA (net free ventilating area) in each endwall, in order to provide sufficient air intake. This may require more than a single vent in each end.

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

Cupola Sizes, Insulation for a Ceiling, and Structural Pieces

This week the Pole Barn Guru tackles reader questions about cupola sizes, the proper way to insulate a shed ceiling, and a structural materials question.

CupolaDEAR POLE BARN GURU: What base size and height is correct for a cupolas for a 32’ wide by 36’ long by 35-40’ high with a 10 over 12 pitch roof? Thank you for your answer. NANCY in SPENCER

DEAR NANCY: This may answer some of your questions: https://www.hansenpolebuildings.com/2015/09/cupola/. As to actual height of your cupola(s) – this is totally subjective based upon what you feel looks best.

 

DEAR POLE BARN GURU: I’m desperately trying to figure out the proper way to insulate my pole shed ceiling. The Purlins run parallel rather than peak to eves. And there are no soffits or vents to be had. I have metal roofing with fiberglass roll insulation between roofing and purlins that has the vapor barrier backing. I’m afraid to slice holes in this vapor barrier as it may cause the metal roofing to condensate. My purlins are conducting cold temps in winter and when the heat hits them, they grow mold in some places as they’re very cold – or hot in the summer. Can I install the paper back fiberglass between purlins and be okay? I’m hoping would slow moisture down. but allow it to dry as well. IDK I’m in the NW mountains of Oregon, we do get low temps and snow and the shop is mildly heated in winter. I can’t afford to redo the roof or go with blown in foam. Is there another way? Can I use fiberglass batting safely? My end goal is to have tin roofing on the ceiling, is that okay? Sorry to bother you with such a common question but I haven’t found anyone with my exact issue. Thanks so much for your time and I sincerely hope to hear from you, big fan, DAVE in GALES CREEK

DEAR DAVE: Appreciate your being a big fan – thank you!

No, you cannot/should not install paper (kraft faced) backed fiberglass insulation between your building’s roof purlins. This would create a system with two vapor barriers, trapping moisture between them. Start by looking to what is probably your source of moisture – your concrete floor. If you do not have a well-sealed vapor barrier underneath it, use a sealant on top of your concrete to reduce moisture coming up through your slab. After you have your steel ceiling in place, blow in fiberglass insulation above it, and install vents in each gable end and under your ridge cap.

 

DEAR POLE BARN GURU: What is the type of steel (cold roll, stainless, etc.) used and the thickness of the trusses and main poles holding the structure up. ERIC in PAHRUMP

DEAR ERIC: 40 years ago I provided a post frame building kit package for a tire dealer in Pahrump!

Most steel roofing and siding is cold roll formed. These panels most typically have SMP paint (https://www.hansenpolebuildings.com/2014/05/smp/) over a galvanized or galvalume substrate. There are Building Code minimum requirements for residential steel roofing substrates (https://www.hansenpolebuildings.com/2020/11/minimum-steel-substrate-coating/). Hansen Pole Buildings use two-ply (for interior spans) 1-1/2″ width (2x lumber) chords and webs for prefabricated roof trusses, assembled with 16, 18 or 20 gauge galvanized steel pressed in connector plates. Plate thickness is determined by truss engineers to meet tension requirements. Main roof supporting members may be either glulaminated or solid sawn timbers, depending upon eave heights, roof slope, applied wind and/or snow loads, dead weight of roof assembly and availability of materials in a given market. Actual sizing will be determined by our third-party engineers.

 

This entry was posted in Pole Barn Structure, Lumber, Insulation, Trusses, Pole Barn Questions, Ventilation, Pole Barn Design, Building Interior, Building Styles and Designs, Roofing Materials, Constructing a Pole Building, Professional Engineer, Pole Building How To Guides and tagged , , , , , , , , , on by .

Ceiling Insulation, Drafting Capabilities, and 24″ On Center Framing

This week the Pole Barn Guru answers reader questions about “ceiling insulation” for a roof rebuild, the capabilities of our drafting and proprietary pricing program, and “what percentage of pole buildings are 24″ on center?”

DEAR POLE BARN GURU: The birds have destroyed the front half of the ceiling insulation in our 40 x 60 pole building. We need a new roof and we plan to take out all the insulation when the roof is done. We don’t know what else to do because if we leave the insulation in the back half of the ceiling, the birds may destroy that also. What do you think? SHARON in STERLING

DEAR SHARON: Typically when I hear people talk about birds having destroyed pole building insulation I think of what is commonly known as Metal Building Insulation. Usually this is a thin layer of fiberglass with a white vinyl face – and once birds get started into it, there is no turning back https://www.hansenpolebuildings.com/2018/09/spot-problems-with-this-pole-barn-photo/

If you are doing a reroof, to control condensation your should look at ordering roof steel with a factory applied I.C.C. https://www.hansenpolebuildings.com/2020/09/integral-condensation-control-2/

 

DEAR POLE BARN GURU: I was curious on what program you use to make your plans? Does it do take off and quotes with the drawings? Can you design the interior also the exterior to make a shouse? TIM in NORFOLK

instant pricingDEAR TIM: Always a pleasure to hear from a “lumber guy”. Our blueprints are actually drafted individually on AutoCAD, however we are gradually transitioning to where most fairly straightforward work will be automated from our trademarked and proprietary “Instant Pricing” system. We searched everywhere trying to find a computer program able to actually accurately do a structural analysis of post frame buildings and found none existed. We created our own and added to it abilities to do real time quotes for any climactic condition and anywhere in America. Our program does quotes, invoices, material takeoffs, creates purchase orders and interfaces with our client data base.

While it can do interior walls, we opted to create a full service program for shouse and barndominium plans with a real person interacting via screen sharing so clients can watch their homes appear before their very eyes from the comfort of their homes.

 

DEAR POLE BARN GURU: What percent of pole barns are on 24″ centers? BRUCE in SXARTZ CREEK

DEAR BRUCE: There are numerous components of post frame (pole barn) buildings often placed 24 inches on center. Among these could be wall girts, roof purlins, sometimes roof trusses (most often seen with shingled roofs), floor joists or floor trusses over crawl spaces, basements and for second or third floors. One of fully engineered post frame building design’s beauties is there is no obligation to be at a specific spacing and materials can be utilized for their full structural capacities – making them extremely cost efficient.

 

 

This entry was posted in Building Styles and Designs, Roofing Materials, Pole Barn Planning, Rebuilding Structures, Lumber, Insulation, Pole Barn Questions and tagged , , , , , , , on by .

Seven Reasons Why Your Next Barndominium Should Be Pole Frame Construction

Today’s blog comes from Don Howe, who is a retired sales executive but has a burning passion for barndominiums.

About Hansen BuildingsSeven Reasons Why Your Next Barndominium Should Be Pole Frame Construction

One of the first design details to consider when building a barndominium is the building process. Most barndominiums are built using a stud frame, steel frame, or pole frame construction. 

 

Wood frame construction uses stud walls to support the roof. Steel frame construction involves the use of large steel frames for wider designs. As with steel frames, pole frames allow for wide, open designs, but typically feature wood posts instead of metal.

So, why should you use pole frame construction for your next barndominium? Here are seven of the top reasons.

  1. More Energy Efficient

Pole frame buildings often have thicker wall cavities compared to other types of buildings. With thicker cavities, you can use more insulation and increase the energy efficiency of the property.

The frame itself is also more energy-efficient compared to steel. The thick timber used for the post columns has natural insulating properties. They also conduct less heat, which may help save on cooling during the warmer months.

Many pole frame barndominiums include an attic, which allows for space for ceiling insulation and enhances air circulation. With the combination of energy-saving benefits, your home is likely to experience less heating and cooling loss through the roof.

  1. Aesthetically Appealing Designs

A pole frame building provides a wide range of design options, including various overhangs and trims. You can also choose from a variety of exteriors, including brick, wood, block, and vinyl siding.

Compared to stud frame homes, pole frame homes also have wider column spacing. Studs are typically spaced up to 24 inches apart while posts are spaced up to eight feet apart. The wider spacing allows for more design flexibility, such as wider windows and doorways.

A pole frame also eliminates the need for interior support columns. This means the interior floor plans do not need to accommodate load-bearing walls. You can have a completely open design spanning the entire floor or add rooms to any area. 

  1. Greater Durability 

With the right contractors, a post frame barndominium can be more durable compared to a steel frame building. The posts are often anchored four feet or more into the ground. When severe weather and wind hit the side of the building, most of the energy is transferred directly to the ground. 

Horizontal girts also connect the post columns, which increases the overall structural integrity of the frame. Trusses are also attached directly to the columns. 

Due to the superior stability of a pole frame building, these types of homes also tend to last longer. The posts are anchored in concrete slabs or basement foundations, protecting them from moisture and bacteria.

  1. More Affordable

Post-frame construction is often more affordable compared to both steel frame and stud frame construction processes. Steel is a relatively costly material for home construction while stud frame designs require additional labor and materials, which increases the costs.

The efficiency of constructing a pole frame building reduces the cost of constructing your barndominium. Thanks to the durability of the design, you are also likely to spend less on maintenance and upkeep in the coming years. 

  1. Faster Assembly

With enough help, people often put up pole barns in a single day. Barndominiums that use pole frame construction may not be completed in one day, but they are quicker to build compared to other construction methods.

As the columns are spaced further apart, there are fewer materials and less work needed to complete the frame. After the frame is erected, the rest of the work can proceed, including putting up interior walls and adding exterior features, such as doors and windows.

  1. Available in Kits

Pole frame barndominiums are available as kits, which simplifies the construction process. You get almost everything needed, including house plans, building materials, hardware, and various prebuilt components, such as doors and windows.

The availability of barndominium kits gives homeowners more control. You are less likely to deal with an overage or underage of materials, reducing the risk of delays and unexpected costs.

While barndominiums are available as kits, most homeowners should still consider hiring a contractor to assemble the home. Contractors can ensure that the frame is erected properly and meets all local building codes.

  1. Add Space for a Barn or Workshop

The original barndominiums were extensions of barns and workshops on farms and rural residential properties, combining workspace with living space. Pole frame construction allows you to continue the original tradition and add space for a barn or workshop.

In the end, pole frame construction offers a wide range of advantages over your other options. Steel frames may offer wider spacing between columns, but they also tend to cost a little more and offer less energy-efficient designs. Compared to pole frames, stud frames are costly and take longer to construct.

If you want fast, affordable, durable construction, consider using a pole frame for your next barndominium.

This entry was posted in Barndominium, Pole Barn Design, Shouse, Constructing a Pole Building, Pole Barn Planning, Building Contractor, Ventilation, Budget, Pole Barn Homes, Post Frame Home, Insulation and tagged , , , , , , , on by .

Insulation, Insulation, Insulation

The Pole Barn Guru discusses the always popular ceiling insulation, vapor barriers with insulation, and closed cell spray foam insulation.

DEAR POLE BARN GURU: I read your article on unvented roofs. My building has a vapor barrier installed. I am at the point of insulation and plan on doing closed cell spray foam. What would be better spraying the roof deck or the attic floor/ top side of the ceiling. I was thinking spraying the roof deck and then doing blown in insulation above the ceiling to get my r value. I thought having the entire building done in closed cell would make for the tightest building. BRAD in FLANAGAN

DEAR BRAD: If you have a condensation control barrier (having a thermal break, not just a vapor barrier) of some kind between roof steel and framing, then there would be no need to closed cell spray foam underside of roof deck, unless you are going to use this as your only insulation.  Insulating ceiling line creates a dead attic space above, so it will need to be ventilated (either eave and ridge or gable vents). Closed cell spray foam will give you a very air tight building, applied properly.

DEAR POLE BARN GURU: Built pole barn installed 1-2 inch thermal sheathing in outside installed 8 inch batt would you install vapor barrier on inside been told I have two vapor barriers answers. JIM in HARTFORD

DEAR JIM: You are going to have insulation sandwiched between two vapor barriers, however air leakage into the cavity is a greater issue than through a vapor barrier. Goal is to keep insulation and wall framing dry. As long as you adequately seal all of the air leakage pathways you would not need an interior vapor barrier. In other words – if you install an electrical outlet or switch box, seal it, seal around any door or window openings.

DEAR POLE BARN GURU: What do you feel is best insulation system for pole buildings building we got is 162 x 72 wood structure built on foundation wall columns on 6 ft on center girts nailed to outside of columns and also inside corrugated metal we installed 1/2 poly iso insulation and 8 inch batts in wall spray foamed  base to seal air leaks and plugged holes on top with 3 inch iso between columns and foamed around window frames poly iso has foil face and we taped seams wanted to install poly vapor barrier on inside but was told that I would have two vapor barriers which is bad what do you recommend? JIM in HARTFORD

DEAR JIM: My recommendation would be two inches of closed cell spray foam on inside of steel siding. Install another set of girts on inside of columns to support interior wall finish material. Fill wall cavity with BIBs (https://www.hansenpolebuildings.com/2011/11/bibs/). Glue two inches of closed cell foam insulation board on inside of girts, sealing around any penetrations. Glue interior finish material to inside of insulation board.

 

 

 

 

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Uplift Concerns, Retro-fitting Insulation, and High Water Tables

This week the Pole Barn Guru answers questions about uplift concerns, retro-fitting insulation, and setting posts in high water tables.

DEAR POLE BARN GURU: I am adding an open overhang to the gable end of my 40×80 pole barn. I bought 36’ trusses and will lower them to fit under the existing gable going out 16’. Since the underside is unfinished should I worry about wind uplift? SCOTT in SHERIDAN

DEAR SCOTT: Regardless of whether your addition will be open, enclosed, or somewhere in between uplift should always be a consideration. Ideally the original EOR (Engineer of Record) who designed your 40′ x 80′ building would be consulted, not only because of a potential uplift issue, but also due to what affect open carport will have upon existing building. You may be placing wind shear issues upon endwall closest to addition and these will need to be addressed, as well as if endwall column footings will be adequate to support added weight (not just dead load, but also potential weight of a snowfall). An issue of drifting needs to be reviewed also, as snow could build up upon carport roof against existing endwall.

If original EOR proves unavailable (or nonexistent), you should enlist services of a competent RDP (Registered Engineer or Architect) qualified to review your existing building, as well as your intended work.

DEAR POLE BARN GURU: Need your suggestions on any improvements I can make. Below is a sketch of my current building roof insulation. Basically I tried to seal off the cathedral ceiling using the bottom of the purlins to hang 4” Dow board sealed with aluminum tape. I did purchase the radiant reflective barrier that was installed per instructions between the roof purlins and the steel roof panels. I live in Michigan.

I love my two pole buildings I purchased from you guys. Just need some help on insulating the roof on my last building. Nothing is wrong. Just concerned about the un-vented dead air space. JOHN in SAGINAW

 

DEAR JOHN: Always glad to hear back from happy building owners! As long as the cavity was dry when it was sealed up, and the Dow board is sufficiently well sealed there is a chance you will not have problems. The only guaranteed solutions involve having to take down the insulation board and make provision for airflow from eave intake to ridge exhaust by drilling holes through all of the purlins.

 

 

DEAR POLE BARN GURU: Mike can you please tell me what is the proper way to set posts in holes that have water. High water table. Thanks much I enjoy your blog. PATRICK

DEAR PATRICK: Back when I was a contractor we would run into this situation occasionally. Our solution then was to stand columns in holes, brace them and then backfill with pre-mix concrete with very little water in it. Concrete weight would displace water in hole. It did take a significant amount of concrete, however it was only about $30 a yard then.

How I would do it now – I would use sonotubes equal to or larger in diameter than what was specified by engineer. Cut tubes to depth of hole length, then cover one end of tube with six ml black visqueen (read about visqueen history here: https://www.hansenpolebuildings.com/2013/07/moisture-barrier/ ) sealed tightly around sides of tube. Place tube in hole with covered end down (this will take some work, as tube will want to float like a boat). Once sonotube has been placed, backfill around outside with compactable material – compacting no more than every six inches. Then stand column in tube, brace it and backfill with pre-mix concrete as engineer specified.

 

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

Post Frame Antiperspirant- Ventilation Frustration

This is a sad story I hear all too often from pole (post frame) building owners who have buildings which were not properly designed for future uses, especially when it comes to insulation and ventilation.

Reader JASON in TENINO writes:

Hi Pole Barn Guru,

I recently purchased a new house and it came with a 40×60 shop. This past year I’ve experienced terrible slab sweating every time there is a change in humidity. Now that it’s summer I would like to prevent the sweating from occurring again. What are my best options on a limited budget? I’ve looked into using a penetrating concrete sealer, but I don’t think that addresses the underlying condensation problem.

As far as I can tell the shop has no ventilation of any kind (ridge/gable/soffit). And I’m noticing black mold starting to develop in the insulation below the roof. And I’m not sure if any sort of vapor barrier was placed before the slab was poured.

In the future I would like to insulate and heat the shop, but for now, I’d be happy if I can stop my condensation problems.

Thank you for your help!!!

DEAR JASON:

Yep – you have a problem on your hands. I can pretty much guarantee there is no vapor barrier under your concrete floor, which is a shame someone cheaped out. Vapor barriers are so inexpensive.

Taking care of first things first, let’s get the floor sealed. Here is the information you will need: https://www.hansenpolebuildings.com/2012/07/concrete-sealer/.

Secondly – 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.

Third – I am going to leap ahead to your future plans, as they will impact your solutions now. I am not a gambling man, but I would put money on your shop’s trusses not having been designed to support the weight of a ceiling. This means if you want to eventually insulate and heat the building, you will have to insulate above the bottom chord of the trusses and up the roof line. On the walls, you can frame in either with a stud wall or with bookshelf girts to create a method to support insulation, with either batts or BIBs (Blow in Blanket) insulation being the most cost efficient and effective for your investment dollars.

Insulating the roof, not so easy, as the only really practical solution will be to use closed cell spray foam between the roof purlins. You will want to consult with an installer to get their opinion as to whether the metal building insulation under the roof steel will have to be removed prior to spraying.

If you are going to spray foam, then you do not want to use a ridge vent, as the foam would cover it.

Here is my best advice (provided you have the space on your property) – use your existing building only for cold storage. Since you do not have vented sidewall overhangs to create an air intake, the only solution for ventilation is to use large vents in each endwall. At a bare minimum, you should have at least 576 square inches on net free flowing vent in each end – located in the top half of the gables. You may need to add power vents, in order to adequately move the moisture out of the building.

When your budget allows for some climate controlled space, construct a new building which is properly designed to be able to be energy efficient.

Here is a short list of features which you should include:

Underslab vapor barrier
Pex tubing in slab for in floor heat
Perimeter slab insulation (rigid foam)
Bookshelf wall girts to create an insulation cavity
Housewrap between wall girts and siding
Vented sidewall overhangs
Ceiling loaded trusses with ceiling joists
Raised heel trusses to allow full insulation depth from wall to wall
Blow in R-45 to 60 of ceiling insulation
Reflective radiant barrier between purlins and roof steel

Good luck and let me know how things turn out!

Mike the Pole Barn Guru

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

How To Add Insulation Between Purlins

If you happen to be considering building a pole building in a part of the country where sidewall columns MUST (it is a mindset, not a structural requirement) be every eight feet and trusses MUST be every two or four feet, then it is time to take a leap of faith out of the very small box!

Read more on truss spacing here: https://www.hansenpolebuildings.com/blog/2011/06/pole-barn-truss-spacing/

On to the topic at hand…..

insulation roll

Whilst I am a proponent of insulating above flat level ceilings, there are cases where this just isn’t what people have in mind for their new post frame buildings. Whether it is to create dramatic vaulted ceilings, or just to be different, every reason is valid.

The challenge is… how to get adequate insulation between purlins into a typically very small area.

With typical “Western” style pole barns, double trusses are placed every 10 to 14 feet with 2×6 or larger roof purlins on edge between the trusses.

Even using high density insulation batts, the R-23 from a 2×6 insulation cavity is only going to be adequate in the deepest South.Ceiling R Values

There ARE solutions….using larger roof purlins being a very simple one. Using high density batts would allow for R-46 in a 2×12 purlin. Or, for increased depth, furring strips could be added to the underside of any sized purlins.

If gypsum wallboard is to be added to the underside of the roof purlins, a deeper purlin is often required to prevent undue deflection from cracking drywall joints.

Oh, I forgot to mention, purlins are best placed 24 inches on center, to fit with the most common insulation width, and insulation between purlins should be unfaced.

Further insulation may be added by the use of high R foam boards placed beneath the purlins; however Code requires them to be covered with a fire barrier on the inhabited side.

For more foam board information: https://www.hansenpolebuildings.com/blog/2012/04/rigid-insulation-boards/ and https://www.hansenpolebuildings.com/blog/2012/04/foam-board/

There IS a challenge, which we have not yet delved into….ventilation is required between the insulation and the roof deck. The roof purlins running the length of the building prohibit airflow, and even if the insulation was not the same thickness as the cavity (depth of the purlin), not enough holes could be drilled through the purlins to allow adequate airflow and not degrade the purlin strength.

The solution: Lay 2x4s flat on top of the purlin, running up the roof. Although these 2×4’s and their connections need to be structurally verified against uplift conditions, in most cases, spaced every four feet will prove adequate. This space will become the “air chase” between vented sidewall overhangs and the vented ridge cap.

On top of this layer of 2×4’s, reflective radiant barriers needs to be placed.  This prevents warm moist air from contacting the underside of the roof steel. Using a product with a tab along one edge with an adhesive pull strip, helps to make sure no air will leak through the vapor barrier. (Go to www.buyreflectiveinsulation.com for reflective radiant barrier information and pricing).

In order to attach the roof steel, yet another layer of flat 2×4 needs to be added. As the previous layer runs from eave to ridge, this layer will be used to attach the roof steel. Spacing of these will be dependent upon the snow and wind loads, but they usually will be no greater than 32 inches on center. Besides affording the ability to attach the purlins to a wide target (the 3-1/2 inch face of the 2×4), the dead air space increases the effectiveness of the reflective radiant barrier.

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

Ask the Guru: Is Vapor Barrier Required?

For those of you just joining Mike the Pole Barn Guru’s Blog – Mondays are now “Ask the Guru” where you can submit construction and building product questions for Mike to answer in upcoming Monday segments of this blog.  If it is a topic Mike is not well versed in, or a new product he has not yet been exposed to –  he will do “due diligence” in his research and give you his best advice.

Submit questions to: PoleBarnGuru@HansenPoleBuildings.com

DEAR POLE BARN GURU:  Finishing & insulating inside pole barn that was here when purchased last year. What are your thoughts on vapor barriers for ceiling between the metal and insulation?

Also in quandary over no over hangs for soffit vents it’s a Mo**on with the gable ends venting where trim meets the ribbed siding, snow blows inside currently and not sure if after I have it closed in it will still do so and get insulation wet (fiberglass). Thanks BLOWING IN, IN OHIO

 

DEAR BLOWING: It is essential to have a vapor barrier between the roof steel and any conditioned area below. In the event there is not a vapor barrier between the roof purlins and the roof steel, there are some options. The best choice, is also the most work.  Remove the roof steel, install a reflective insulation on top of the purlins and reinstall the roof steel, using larger diameter, longer screws than what originally held it in place. Spray foam insulation could be placed on the underside of the roof steel (may be cost prohibitive), or reflective insulation could be installed under the roof purlins, as long as all of the seams are tightly sealed.

Assuming you are placing the fiberglass insulation at ceiling level, there should not be a vapor barrier below it. You want any warm moist air from inside the building to be able to rise into the dead attic space, which must be adequately vented. Venting can be accomplished by a combination of sidewall eave vents and a vented ridge, or by gable endwall vents.

 If snow is coming in under the gable end/rake trim, the screws can be removed from the gable face of the trim, expanding closures can be placed along the edge of where the trim lies, and then reinstall the trim using metal-to-metal stitch screws. The expanding closures should be placed so the lower edge of the closure is just covered by the trim.

 In any case, you want to be certain any fiberglass insulation will not get damp, as it will lose its effectiveness, as well as possibly contributing to decay of any wood members it is in contact with.

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