Tag Archives: closed cell spray foam insulation

My Pole Barn is Chilly

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

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

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

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

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

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

Made spray foam sound easy, didn’t I?

Air Sealing Your Post Frame Barndominium

Unless someone reincarnates Nikola Tesla (and he is sane) chances are good energy costs are not going to decrease. Air sealing your post frame barndominium or shouse increases your comfort by reducing drafts and cycle time your heating and cooling systems are running.

Air sealing your barndominium reduces humidity increasing comfort levels. A drafty barndominium is more than just a waste of natural resources, it also means higher energy bills. Air sealing will automatically lower your energy bills due to less leakage of conditioned air.

Using two inches of closed cell spray foam directly inside steel siding panels not only air seals exterior walls, as it is an effective vapor barrier, but also provides approximately a R-14 level of insulation. Effective applications also require installing form fitted inside closure strips at top and bottom of every wall steel panel – including window and door openings. Closure strips keep spray foam in your walls rather than oozing out and keeps small crawling and flying critters out.

For those who opt not to utilize closed cell spray foam, air sealing begins with a totally sealed Weather Resistant Barrier (WRB) wrapping all framing before steel siding is applied. For further reading on Weather Resistant Barriers please see: https://www.hansenpolebuildings.com/2016/01/determining-the-most-effective-building-weather-resistant-barrier-part-1/

Care should be taken to effectively use WRBs around openings for windows and doors, as well as utilizing caulking and self-adhesive sealant tape for an airtight seal. Place sill gaskets under all exterior doors. Use spray foam or caulk to fill any gaps between doors and windows and adjacent framing.

In Floor Heat System InstallationWhen placing under slab vapor barriers, run up inside of pressure preservative treated splash planks and sealing to top and around columns. Install seal gasket under pressure treated base plate (mud sill) and caulk inside edge to concrete slab.

With wall insulation systems other than closed cell, use a clear visqueen vapor barrier on the inside of all framing. Seal every penetration in this vapor barrier.

Before installing interior window and door trims, caulk where trim will meet frames. Make sure door sweeps are installed and the threshold is properly adjusted.

Common infiltration paths include attic access and simply insulating envelope (or shell) isn’t enough. In fact, insulation’s ability to perform is almost cut in “half” if not air sealed first.

Expandable polyurethane is used in areas too wide for caulk. If an area is wider than 1/4″ caulk can fall out of grooves. Acrylic-latex caulk is for all gaps small enough for caulk to function properly such as base plate and seam between floor and wall and wall and ceiling. Fire-rated caulk is non-combustible and for any areas where wires penetrate through base plates, walls, etc. (This is a recently implemented new national code.)

While it seems obvious gaps and crevices in a barndominium should be sealed, most builders either have not yet begun or just recently started utilizing air sealing processes. If hiring a contractor, make certain complete air sealing processes are spelled out in contractual documents – money you will save over your barndominium’s lifespan.

Installing Steel Liner Panels in an Existing Pole Barn

Installing Steel Liner Panels in an Existing Pole Barn

Reader JASON in WHITEHOUSE STATION writes:

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

Mike the Pole Barn Guru responds:

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

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

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

Imagining a Retirement Barndominium

Let us face it – I am among those greying in America. According to United States demographic statistics 14.7% of us (over 41 million) have reached a 62 year-old milestone!

What are we looking forward to in our probably final home of our own? We want to be able to spend our time enjoying life, rather than being slaves to home upkeep.

Loyal reader RUSS in PIPERSVILLE writes:

“We are currently in the “imagining” phase of our retirement home. We hope to be building in Maryland very close to the Chesapeake Bay.

We are trying to plan it as an aging in place home. The building will have the top of floor at 4ft. so as to accommodate the recorded last worst flood tide of 11 feet on the bay. Building dimensions are approx. 30 x 60 with a 9ft interior ceiling height. Do you favor engineered floor joists over dimensional lumber and why?

Planning to use Roxul insulation in the walls for R-30. A 2×8 bookshelf girt is 7.25 in. the same as the insulation batts. Can the insulation be place directly
against steel siding if we choose that system?

Also pretty sure that we will be specifying raised heel trusses for the roof. Can the steel siding accommodate the shear requirements for the trusses and an upgrade of wind load specs, or would something like tall wall or storm side sheathing become more practical? 

I am convinced that you folks are the only company that we will trust with the design and supply of our home. Your blog and learning posts have been an incredible help in this process. Without the information that you folks publish we probably would have made a serious mistake in looking elsewhere for this.”


Mike the Pole Barn Guru says:
Thank you very much Russ for your kind words, they are appreciated.

My thoughts:

I would consider setting underside of my floor framing to be above the highest recorded flood tide and probably give it an extra six inches. As the floor is being elevated, might as well make sure it is never going to be an issue.

I’d look at 10′ ceilings, as well as 9′. You are going to be designing for energy efficiency so heating/cooling differences should be minimal and those 10 foot ceilings are sure nice. Makes everything feel so much more spacious.

About Hansen BuildingsMy preference is engineered prefabricated wood floor trusses. To me, I joists always feel spongy. Dimensional lumber varies greatly in both height dimension as well as stiffness of each piece leading to a feeling of lots of ups and downs as you walk across a floor. Both of the last two make running duct work and plumbing within floor cavity near impossible – leaving things having to hang below the floor’s finished underside.

You can place Roxul directly against wall steel inside, however I would use a Weather Resistant Barrier if going this direction. Me personally, I would flash spray two inches of closed cell foam to wall steel inside and then use 5-1/2 inch batts. Closed cell spray foam completely seals your walls and adds rigidity. You would end up with roughly R-37 walls.

Because your trusses are connected directly to sidewall columns, raised truss heels do not create a greater shear load for sidewall steel.

Try to plan your interior spaces to best fit your needs, rather than to try to fit your needs inside into a preconceived exterior box, a difference of a few cents per square foot is not worth the sacrifice of a needed space. Maximize southern windows and minimize or eliminate north facing ones. Plan southern roof overhangs to shield windows from summer sun. 

I appreciate your well thought out questions and looking forward to being with you on your continued journey.

How Tall Should My Eave Height Be for Two Stories?

How Tall Should My Eave Height Be for Two Stories?

I have learned a couple of things in 40 years of post frame building construction. One amongst these is – most people are dimensionally challenged (no offense intended).

As much as some folks would like to believe, you cannot legitimately put two full height finished floors in a 16 foot eave height post frame building.

Now fear is a strong motivating force. Perhaps it is fear of a building “appearing” too tall or of OMG it will be too expensive keeping people from considering what it actually takes to create a Building Code conforming two story building.

Back in my early roof truss selling days, I had two clients who had relocated from New York state to North Idaho and were building new homes on adjacent properties. Both of them (and their spouses) were relatively short of stature and had decided to build their homes to Code minimum ceiling heights of seven feet. Their reasoning was it would be less space to heat and cool and they could chop two studs out of 14 foot long materials.

Missed in all of this was how much sheetrock waste would be created!

Sidebar – modern Building Codes allow seven foot ceilings under International Residential Code (IRC), however IBC (International Building Code) requires six more inches.

Now I am vertically challenged at 6’5” and would feel very uncomfortable with seven foot ceilings. In my own personal shouse, most ceilings on both floors are 16 feet high!

In today’s exciting episode we will learn together how tall eave heights should actually be to give reasonable ceilings in post frame buildings.

Setting a “zero point” at exterior grade (and assuming slab on grade for lower floor), top of slab will be at +3.5 inches.

To create eight foot finished ceilings requires 8’ 1-1/8” (allows for 5/8” sheetrock on ceilings).

In order to be able to run utilities (e.g. plumbing and ductwork) through second floor supports, I highly recommend prefabricated wood floor trusses (https://www.hansenpolebuildings.com/2020/01/floor-trusses-for-barndominiums/). Generally truss height will be about an inch for every foot of clearspan with a 12 inch minimum. 

In my own shouse, we have a 48 foot clearspan floor over our basketball court. And yes, those trusses are four feet deep!

Allow ¾ inch for OSB floor sheeting.

6-1/16″ for heel height of trusses with 2×6 top chord at 4/12 slope (provided you are using closed cell spray foam insulation between purlins)

If using blown-in insulation truss heel height should be R value of insulation divided by 3 plus 2″ to allow plenty of eave to ridge air flow above insulation.

At a bare minimum an eave height of 18’ 0-9/16” will be needed to create those eight foot ceilings.

Whole House Barndominium Fans

Whole House Barndominium Fans

Apparently when it comes to barndominiums, there is a limitless number of subjects to cover!

Reader CAROLYN in CLEVELAND writes:

“We would like to build a post frame home but I would like to have a whole house fan to cut down on cooling costs. Most barndos we see under construction use spray foam insulation directly against the metal roofing/ siding which would prevent the use of a whole house fan. You talk about blown in insulation and roof venting which sounds similar to stick built homes. So is it safe to assume that your designs would allow us to install a whole house fan in the attic space with adequate venting? I fondly recall the ancient airplane engine attic fans 3 or 4 ft wide from years ago and was pleasantly surprised to see the new ones drastically reduced in size and volume. What is your opinion on this?”

Mike the Pole Barn Guru responds:

Most Hansen Pole Buildings’ post frame barndominiums are designed with dead attic spaces – blown in insulation above a sheetrocked ceiling (yes, very similar to stick built homes). This would certainly allow for use of a whole house fan and could prove to be very effective. I would still encourage use of a flash coat of closed cell spray foam insulation inside your barndominium’s wall steel. (For extended reading on flash and batt: https://www.hansenpolebuildings.com/2020/01/flash-and-batt-insulating-barndominium-walls/).

In most climates whole house cooling using a whole house fan can substitute for an air conditioner. Combined with ceiling fans and other circulating fans, whole house fans provide acceptable summer comfort for many families, even in hot weather. In addition to whole house fans, central heating and cooling system ducts can be modified to provide whole house cooling.

A whole house fan pulls air in from open windows and exhausts it through the attic and roof. It provides good attic ventilation in addition to whole house cooling. Whole house fans should provide houses with 3 to 6 air changes per hour (varies with climate, floor plan, etc.—check with a professional to determine what is appropriate for your home). Air-change rate you will choose depends on your climate and how much you will depend on your whole house fan for cooling.

Installing a whole house fan can be tricky and should be done by a professional. An experienced professional should take your attic measurements and install your dedicated circuit wiring and, if needed, your new attic vents.

Attic ventilation will usually need to be increased to exhaust fan’s air outdoors. You’ll need two to four times the normal area of attic vents, or about one square foot of net free area for every 750 cubic feet per minute of fan capacity. Code requirements for dead attic space venting are 1/300th of the attic “footprint” with at least half of this located in the upper half of the attic. Net free area of a vent takes into account resistance offered by its louvers and insect screens. More vent area is better for optimal whole house fan performance.

If your fan doesn’t come with a tight-sealing winter cover, you should either buy one or build one. If you switch between air conditioning and cooling with a whole house fan as summer weather changes, build a tightly sealed, hinged door for fan opening easy to open and close when switching cooling methods.

Be cautious when operating these large exhaust fans. Open windows throughout the barndominium to prevent a powerful and concentrated suction in one location. If enough ventilation isn’t provided, these fans can cause a backdraft in your furnace, water heater or gas-fired dryer, pulling combustion products such as carbon monoxide into your living space.

Whole house fans can be noisy, especially if improperly installed. In general, a large-capacity fan running at low speed makes less noise than a small fan operating at high speed. All whole house fans should be installed with rubber or felt gaskets to dampen noise. You can set a multi-speed fan to a lower speed when noise is a problem.

You may be able to use heating and air conditioning ducts in your barndominium as a means of whole house ventilation. This would involve installing an intake duct to pull air into an attic-mounted system directing air into your heating and cooling ducts. A damper would control exhaust air from your home into the attic. Check with a local HVAC professional to find out if this option is right for you.

Beginning a Shouse Journey in Washington State Part II

For many readers, you might be considering your new barndominium to be constructed in a jurisdiction without state energy requirements such as those in Washington State. Granted, Washington is a state either on the forefront, or totally out of control, when it comes to mandated energy efficiency, however fuels are not going to get any less expensive, so it is likely you should follow along to design a system combining practicality with efficiency.

Here is my response to yesterday’s writer, Robert:

Thank you very much for your kind words and for being a loyal reader.

Washington Energy Code would be adding to your expense if you were not planning on at least some sort of climate control in your shop area. You can review the current Washington State Energy Code at: www.seattle.gov/documents/Departments/SCI/Codes/SeattleEnergyCode/2015WaStateResidentialEnergyCode.pdf

About Hansen BuildingsWith only 1200 square feet of living space, you should be able to easily exceed the state mandated required number of energy efficiency credits. We are currently changing our standard windows to U-29, meeting Washington’s standards. Lesser U values are available, however added expense may well not ever be recouped by energy savings. I would recommend two inches of closed cell spray foam on your walls, then BIBs or similar to fill the balance of wall cavity. R-49 attic insulation is mandated by Code, however your added investment to go to R-60 would be minimal. With either we would recommend raised heel trusses.

ERV systems appear to be a good investment. With a 90% or greater effective rate you could see an improvement of up to five factors in energy loss.

Your shop area will be classified as S-2 given it is over 1000 square feet. This will require a one-hour fire separation between living area and shop (two layers of 5/8″ Type X drywall will accomplish this). Only savings on insurance I can see by two individual structures would be in valuation of your contents, most typically 70% of your home value. You might reach out to your Insurance agent to further discuss your situation.

Radiant in floor heat is wonderful. You can create individual zones to allow you to heat areas individually. https://www.hansenpolebuildings.com/2018/06/geothermal-heating-cooling/

On drainage plans, I would recommend you contact whomever did existing ones for this site. Chances are little modification would need to be done.

Caleb (a very savvy Hansen Buildings Building Designer)  will be reaching out to you to discuss pricing of your building shell or shells. We also have available a service to create custom floor plans based upon your individual needs. In this article are links to determine various rooms and sizes as well as a final link, to get floor plans for you. https://www.hansenpolebuildings.com/2019/10/show-me-your-barndominium-plans-please/ .

While “turn key” does exist, you can look at a savings of roughly 25% just to act as your own General Contractor. 

I will look forward to accompanying you on your journey!

Ganged Wood Trusses & Closed Cell Spray Foam Post Frame Condensation Control

Ganged Wood Trusses and Closed Cell Spray Foam Post Frame Condensation Control

Ganged wood trusses are most usually two individually fabricated metal connector plated roof trusses, fastened together with either nails or even better Simpson Drive Screws (https://www.hansenpolebuildings.com/2017/03/simpson-drive-screws/), so they work together as a conjoined pair.

True doubled trusses (not two single trusses spaced apart by blocking) afford many structural advantages (https://www.hansenpolebuildings.com/2018/09/true-double-trusses/). However if closed cell spray foam is being used to control condensation underneath steel roofing, a little extra prevention is worth a pound (or two) of cure.

Most often conditioned post frame buildings are designed around having a flat (or slightly sloped using scissor trusses) ceiling. Warm moist air from this conditioned space rises into building’s attic and hopefully has a place to go. Most generally best design solution involves venting this dead attic space. Appropriate amounts of air intake provided by eave soffit vents and air exhaust utilizing a vented ridge will eliminate most moisture.

As those of us who did not nap during science classes are aware – warm air rises. Some of this warm air will get trapped below roof purlins or other attic framing members and not exhaust as imagined.

There are many methods of controlling or eliminating this warm and moist air from coming into contact with cooler roof steel. Least expensive (although potentially labor intensive if windy) would be a reflective radiant barrier (https://www.hansenpolebuildings.com/2017/05/effective-reflective-insulation/). One step up in investment, but very easily installed, would be an Integral Condensation Control (https://www.hansenpolebuildings.com/2017/03/integral-condensation-control/).

Some folks opt to sheath over trusses and roof purlins with OSB (Oriented Strand Board) or plywood, with 30# asphalt impregnated paper (roofing felt) placed between sheathing and roof steel. This can tend to run up one’s investment, as not only will more material and labor be directly involved, but trusses also must be appropriately designed for added weight carrying ability.

Enter closed cell spray foam. Long time readers have grown tired of me solving condensation challenges by people who did participate in one of these solutions and are now faced with a drip-drip-drip. Two inches of closed cell spray foam applied beneath a steel roof between purlins and trusses will create an almost entirely effective thermal break and take care of nearly all condensation issues.

Except…..
Metal connector plates trusses have pressed steel plates on each side. These plates project slightly from lumber faces and when two trusses are joined together, some gaps will occur between them. Gaps wide enough to allow for a significant flow of warm moist air to reach your roof steel, condense and start wreaking havoc.

There is, however, a simple fix, easily done during building framing. Before conjoining two or more trusses, place enough urethane or acoustic caulking between top cords to provide a complete air seal when in service!

Tstud for Post Frame Bookshelf Wall Girts

Tstud™ for Post Frame Bookshelf Wall Girts

I have been somewhat enamored of Tstuds’ potential since one of our clients asked if they would be a viable option last summer.

First I had to find out what a Tstud even was, as I had never heard of them before. Once you skip past ads at the start of this video, it gives a pretty good idea of how Tstuds work in traditional stick frame construction: https://www.youtube.com/watch?t=140s&v=mxDSulcLpAE.

Framing with Tstuds minimizes air infiltration, reduces carbon footprints and saves on electrical energy costs.

A lumber frame is obviously great for providing post frame buildings’ structural integrity. However, this same framing is also a massive weak spot in a wall insulation system – where external air can easily infiltrate. Traditionally a Weather Resistant Barrier (https://www.hansenpolebuildings.com/2016/01/determining-the-most-effective-building-weather-resistant-barrier-part-1/) is used to cover a post frame home, shouse (shop/house) or barndominium and blanket those weak points.

Tstuds are a new engineered framing product, essentially framing lumber with an insulated core. Tstuds consist of two long wood 2×3 members connected by crisscrossing dowels factory filled with closed cell spray foam. A 2×6 has an R-5.5 value, where a similarly sized Tstud is R-20 (or equivalent to a 2×6 wall cavity filled with fiberglass batt insulation).

Tstud’s thermal benefits are undoubtedly their main draw. Their closed cell foam core gives it roughly three times as much insulation value as a typical 2×6 bookshelf girt. By framing with Tstud wall girts and filling in wall cavities with batt insulation, there is no need to consider having to add exterior insulation.  As long term readers of this column are aware, exterior insulation, for post frame buildings, takes away or eliminates diaphragm strength of steel siding. 

Another structural benefit with using Tstuds for bookshelf wall girts is they have engineering tests showing they are up to three times stronger than a #2 graded 2×6!

Now some possible downsides, distribution and availability is highly limited. And (according to Tstud), “We are retailing about the same price as an LVL stud but we are obviously a 5 in 1 solution. In the future we will be about the price as an LSL stud”.

The Home Depot® currently has a 2x4x8 foot LVL stud at $50 or $9375 per thousand board feet. This would make a 12 foot long 2×8 Tstud wall girt roughly $150 or over 11 times more than equivalent sized dimensional lumber. Picking arbitrarily a 36 foot by 48 foot post frame building with a 12 foot eave, this would add nearly $10,000 to your cost of materials! While nifty in design, it is not for the pocketbook faint of heart.

Overhead Door Header Problems

Overhead Door Header Problems (and More)


Reader MITCH in NASHVILLE writes:

“I recently purchased a property that the previous owner had just built a 30×50 pole barn on. It has foil faced double bubble on the roof and walls. I need to heat and possibly cool the space. What are the options for insulating the ceiling? The ridge is vented. There is no soffit and thus no vent there. The trusses are 5ft apart. Your all-seeing wisdom is appreciated.”

There are times I wish I was not what Mitch feels is “all-seeing”, because I find lots of problems in photos building owners are unaware of. 

Back in my post frame building contractor days I would go visit some of our newly constructed buildings, as time and logistics allowed. I generally had very, very good crews and we had an extremely high satisfaction rate from our clients. I would find things wrong (in my eyes anyhow) and send crews out to make repairs. More than once I would field phone calls from clients asking what was going on. They were perfectly happy with their buildings. I would explain to them they might be satisfied, but I was not!

Mitch’s photo shows a frequent challenge posed with post frame buildings where headers (in this case more appropriately known as truss carriers), support trusses between columns. I am not a gambler, but would place money on this not having been an engineered building. Just guessing, this builder used the same size truss carrier for all locations. Usually these truss carriers would be sized to support a single truss centered between two columns. Here, due to door location and width, this carrier supports two trusses, or double what it should have been carrying. 

Look back at this photo – there is a noticeable sag across overhead door top! This same sag will be evident along sidewall eave line outside.

Before any thoughts of insulating are considered, a competent professional engineer should be engaged to design an appropriate repair for this header. Engineer should be advised this header will also need to be capable of handling the weight of a ceiling without undue deflection occurring.

Moving forward, contact the roof truss manufacturer to get a truss repair to upgrade trusses to support at least a five psf (pounds per square foot) bottom chord dead load, with 10 psf being even better. Each truss should be stamped with information of who fabricated them.

Once header and truss repairs have been completed, use white duct tape to seal all gaps present in your roof’s radiant reflective barrier. Without these being sealed, there is a potential for warm moist air to get between barrier and roof steel and condensing.

Place ceiling joists on hangers between roof truss bottom chords every two feet. Your previously engaged engineer can verify if 2×4 Standard ceiling joists will be adequate.

Install vents in each gable end. Placed in the top half of each gable, a net free venting area of 360 square inches or more will be required for each endwall.

Hang 5/8” Type X gypsum wallboard on bottom of ceiling joists, leaving an attic access somewhere towards building center. Have a spray foam insulation installer apply closed cell foam along a two foot strip closest to each sidewall. Blow in fiberglass, cellulose or rock wool insulation across remainder of ceiling surface.

When Attic Insulation is Baffling

Proper insulation provisions seem to be one of the least considered items when it comes to post frame (pole building) planning.

Here is a case in point from reader JOHN in BEND:

“We have just built a 32’ x 48’ pole building with commercial GIRT construction, metal siding, 4/12 pitch metal roof, concrete floor, 12 ft ceilings located in the high desert region of central Oregon.  The building will be used as a training center for a sport shooting club, and only occasionally occupied/heated.

We plan to insulate the walls and (flat) ceiling with R19 fiberglass batts and cover both walls & ceiling with 5/8” drywall.  We have some questions/concerns about adequate venting for the attic area above the ceiling.  We had a vent-a-ridge installed along the entire length of the building (48ft which will provide about 5 sq ft of roof ventilation).  We are now installing 4″ round soffit vents to match the 5 sq ft ridge vent to provide airflow.  We had also planned on installing styrofoam soffit/rafter baffles to ensure the fiberglass batts didn’t block the natural airflow from the soffits.  Then we noticed that the purlins run horizontally very near to the soffits.  The styrofoam baffles appear to be designed for vertical facing rafters that will naturally channel air up towards the vents.  Now we are wondering if styrofoam baffles (and our venting scheme in general) will work properly and whether we need to also install gable end vents.

Thanks for the help. We are a volunteer organization and just don’t have the construction expertise.”

From your photo, it appears the ceiling joist closest to the inside of the wall is a 2×6 with airspace above it. If so, your R-19 batt insulation will still have airflow above it. The baffles you invested in should be returned for credit, as they are not applicable for a post frame installation with widely spaced trusses. 

Now your true challenge, R-19 insulation is woefully inadequate for your location. Your attic should have at least R-49 (https://www.energystar.gov/index.cfm?c=home_sealing.hm_improvement_insulation_table) which would be about 16″ of blown in insulation.

Normally I would recommend to clients to have raised heel trusses to allow for full insulation thickness. In your case, I would recommend the area in the three to four feet closest to the sidewalls to be insulated with closed cell spray foam on top of the ceiling, to the thickness of the ceiling joists, then blow in fiberglass for the balance of the attic. Do not use faced batt insulation.

Converting a Pole Barn into a Home

I happen to live in a post-frame home. It was designed to be lived in from day one, so we did not face obstacles in having to convert a pole barn.

Reader DAN in SIDNEY writes:

“I have an existing pole barn that has no current foundation. It looks like 6×6 pt poles right into the ground. I am trying to convert the pole barn into a home and my first task on my list was a foundation. I was told required by code I need a frost protected shallow foundation. My question is what is the best way to add these footers with my poles already in the ground? Do I just pour around it or extend my pour outside the poles a few inches? Thank you for your time.”

Well DAN I will gladly assist with answers to your challenge, however first I might end up bursting your bubble.

Your building itself could very well pose some other challenges. Most often these come from walls not stiff enough (from a deflection standpoint) to prevent cracking of any gypsum wallboard surfaces. This is an area to be looked into by a RDP (Registered Design Professional – architect or engineer) you are going to hire (please nod your head yes).

 

Chances are excellent roof trusses in your building are not designed to support a ceiling load. If you do not have original sealed truss drawings for your building, you will need to contact whomever fabricated them. Every truss should have an ink stamp stating who manufactured them somewhere along their bottom chord.

Gambrel roof pole barnIn many cases it may be possible for an engineered truss repair to be made, to upgrade load carrying capacity of truss bottom chords to a minimum of five psf. I’m sorry to say, this is not free. Truss company’s engineer will need to put his or her license on the line in designing a “fix” for trusses designed for a load other than is now intended.  It’s not same as designing original trusses.  If you think about it, redesigning and augmenting something you have built, is always more time consuming (and brain challenging!) than first time around. His time and expertise are not without a charge.  It’s not usually “much”, like a couple hundred dollars.  Then there is cost of materials to do repairs. This will be final out-of-pocket expense if you are doing truss repairs yourself.  If not, a contractor’s charge must be added.  All totaled, it could run you anywhere from a couple hundred dollars to over a thousand or more.

Siding should probably be removed and reinstalled with a Weather Resistant Barrier underneath, or plan upon using a two inch or thicker flash coat of closed cell spray foam insulation against siding insides.  If a dead attic space has been created, attic area needs to be adequately ventilated to prevent condensation. You can find out more about adequate attic ventilation here: https://www.hansenpolebuildings.com/2012/08/ventilation-blows/.

Once you have decided to survive all of the above, let’s deal with your FPSF (Frost Protected Shallow Foundation). This article: https://www.hansenpolebuildings.com/2019/02/minimizing-excavation-in-post-frame-buildings/ addresses an FPSF scenario for new post-frame construction. In your case you can follow along doing essentially the same thing, although your columns are already in ground.

Ultimately your conversions costs may exceed starting from scratch and erecting a new post frame building designed to be your home from start. If this is your case, please call and discuss with a Hansen Pole Buildings’ Designer at (866)200-9657.

Help Me Insulate My Pole Building

This story is sad, to me. As post frame building “experts” we (an industry collective we) owe it to our clients to educate them at design phase to avoid a situation such as reader ERIC in SPOKANE VALLEY has become happily (or maybe less happy) involved in.

Eric writes:

“I want to start insulating my pole building. 30x40x16, roof layers are metal, synthetic underlayment, osb, 2×8 purlins. My question is, can I leave an air gap between roof and insulation, as I plan on using R19 batting and covering with facing. Has an open ridge vent. Thank you.”

Mike the Pole Barn Guru responds:

Placing batts between purlins is probably not a Top Twenty best answer for several reasons:

If you do not completely fill purlin cavities, Code requires airflow from eave to ridge over top of the insulation. You have no way to achieve this without a major remodel. You don’t even want to go there.

Getting a perfectly sealed vapor barrier under purlins would be nearly impossible to achieve.

You would have to seal the ridge vent (it isn’t working anyhow, because your building does not have an air intake from enclosed vented soffits).

While installing a flat ceiling at truss bottom chord height might appear to be a quick solution, it also is fraught with some perils:

Trusses are probably not designed to support a ceiling load. It might be possible to obtain an engineered repair from the company who produced your building’s trusses.

Ventilation system would need to be addressed for newly created dead attic space.

Closed cell spray foam insulation would need to be added in the area closest to eave sidewalls.

Weighing what you have to start with, my recommendation is to spray three inches of closed cell foam insulation below your roof sheathing. This will provide a greater R value than R19 batts and provides a vapor barrier. You will need to seal off the ridge (foam installer may be able to just spray foam underside).

Also, I notice in your photo what appears to be a total absence of truss web and bottom chord bracing. I’d have to have a copy of your building’s sealed plans, a truss drawing and some more photos to truly discern.

How Could This Have Been Avoided?

Whoever provided this post frame building should have been asking some important questions:

Will you, or anyone who might own this building in future years ever want to climate control (heat, cool or both)?

If yes, what method of roof insulation is being considered? I like insulation over a flat level ceiling personally, as I then no longer pay to heat or cool the attic area. In order to do this right, energy heels (https://www.hansenpolebuildings.com/2012/07/raised-heel-trusses/) should be utilized. It also means having adequate attic insulation with soffit vents as intakes and ridge vents as exhaust.

It all could have been so much simpler.