Tag Archives: integral condensation control

Texas Post Frame Barndominium Insulation

Reader KIMBERLY in LINDEN writes:

“We are building a 52x40x10 post frame home in East Texas.  The entire thing will be living space.  I have been researching as much as possible on the best way to insulate a post frame home with metal siding and roof.  The information is overwhelming and you get a completely different answer depending on who you talk to.  I know not to skimp on insulation, but the consensus on most “barndominium” FaceBook groups is that spray foam is the only way to go.  I have reservations about that, because it may be a superior way to insulate, but it depends almost exclusively on who is doing the actual foam application.  On top of that you need to spend more money on your HVAC system to add the proper ventilation/air exchange.

I want a well insulated home that is specific to the type of building material and location we live in.  To me, “not skimping” on insulation doesn’t mean that it has to be the most expensive insulation either.  

I also know the insulation world is constantly changing and evolving, but what would your recommendation be to insulate our home in East Texas?

Thank you so much for your time!”

Mike the Pole Barn Guru responds:

Your insulation requirements will vary depending upon where you are in East Texas. Climates zone 1 (closest to Gulf) require R-30 ceilings, R-13 walls. Zone 2 requires ceilings to be R-49 and zone 3 (farthest north) goes to R-20 walls. You can look up you county’s climate zone here: https://codes.iccsafe.org/content/IECC2021P1/chapter-3-re-general-requirements#IECC2021P1_RE_Ch03_SecR301. I will cheat for you and tell you Cass County is Climate zone 3A.

For sake of discussion we will assume you have a dead attic space and will be insulating directly above a finished ceiling.  I would ventilate your dead attic space at the eave (air intake) and the ridge (air exhaust). Make provisions for preventing condensation on the underside of roof steel by having some sort of a thermal break. My personal preference is by using an Integral Condensation Control (https://www.hansenpolebuildings.com/2020/09/integral-condensation-control-2/).  You will want to order roof trusses with raised heels (https://www.hansenpolebuildings.com/2012/07/raised-heel-trusses/), so you can get full insulation depth from wall-to-wall with blown in fiberglass. Heel height should be R value of insulation divided by three and add two inches so you can achieve adequate airflow above insulation.

Should you want to condition your attic – delete ventilation, raised heels and the Integral Condensation Control. I would apply closed cell spray foam two inches to the underside of roof steel, then add open cell spray foam to desired R value.

For walls – best results will be from two inches of closed cell sprayed to inside of wall steel, then fill balance of wall cavity with either open cell spray foam, or unfaced batts (ideally stone wool https://www.hansenpolebuildings.com/2013/03/roxul-insulation/). You could also use BIBs to fill (https://www.hansenpolebuildings.com/2011/11/bibs/). Do not place a Weather Resistant Barrier (WRB) under wall steel or a vapor barrier on inside of wall.

As an alternative to spray foam, you can use a WRB between framing and wall steel, then BIBs with an interior vapor barrier or faced batt insulation.

Energy costs are not going to go down, so I would encourage you to err towards more insulation rather than less – and (since most heat loss is upward) invest more into added ceiling insulation than walls.

In warmer, humid climates like yours, your HVAC system should include an Energy Recovery Ventilator (ERV) regardless of what your choice of insulation systems ends up being.

Don’t Let Valleys Get You Down

When it comes to post frame barndominiums, rooflines run from simple gabled roofs, to complex designs including hips, valleys, reverse gables, etc. Basically, if you can imagine it, post frame can provide a design solution.

Loyal reader (and my Facebook friend) RUSS in PIPERSVILLE writes:

“Hello Mike. As we get a little further along with our design I would like to ask for your opinion. I read in past blog topics that you don’t recommend designing roofs with valleys when going metal over purlins. Our current plan has a large reverse gable on the front of the house covering the entry and porch and our utility mechanical room is a reverse gable room attached at the rear. All roofs are 6/12 pitch. I’m a bit worried about getting the details right. Is it that difficult to install the metal roof correctly over purlins, or should I just consider installing solid sheathing with metal over? Perhaps forego the metal and return to wood deck and shingles? Tom Z. has been a help in explaining how the gables must be framed but I must confess that the details don’t leave me all warm and fuzzy about the roof construction. Any insight you can offer is always appreciated.”

Mike the Pole Barn Guru says:
If I led you to believe I have issues with valleys on steel roofing over purlins I somehow took you astray.

In order to have a successful valley, these steps are followed:

Main roof is framed up, including purlins across area where reverse gable will intersect. 2×12 blocking is then placed between main roof purlins, centered on what will eventually be the middle of the valley. This provides a landing point for intersecting roof purlins from reverse gable (next to be installed). Once these purlins are in place, any reflective radiant barrier (RRB) is installed (I prefer using roof steel with Integral Condensation Control to a RRB). Valley flashing is then installed. We furnish Emseal® self-expanding foam closures to seal between valley flashing and roof steel, following slope of valley flashing. Roof steel is then applied and you are buttoned up tight.

Most challenging parts of assembly are cutting intersecting roof purlins (besides cut being at a 26.6 degree angle along wide face of purlin, cut also needs to be done at 26.6 degrees from perpendicular to compensate for slope of intersecting purlins from vertical) and cutting roof steel at valley to end up with a nice straight line up valley. Neither one is actually beyond most people’s abilities.

There really is no structural advantage to solid sheeting your roof and even the best of shingles have a very poor warranty and I cannot, in all good conscience recommend them as a practical design solution.

For extended reading on Emseal® closures: https://www.hansenpolebuildings.com/2016/03/emseal-self-expanding-sealant-tape-closures/

Must Do’s for a Worry Free Barndominium

My Facebook friend RICK in MALDEN messaged me:

“I have never built a building like this. I have seen many bad experiences with concrete, poor quality metal work and many more issues. I would just like to know if there is a list of things to make sure I get a quality home. I saw the other day you said osb under the roof metal could help with condensation issues. I’m also worried about gaps where the metal meets together. I don’t want to just shoot spray insulation and call it good. You have said that is not the way to do it. I guess I’m looking for something to tell me the quality method for the most common mistakes people or contractors make. I am using a contractor because I don’t have the skill or experience to DIY. I also don’t want to rely on the contractor to tell me the right way. If I had it my way I’d have you do it. You are the most knowledgeable and in-depth person I have found on the internet about the Barndo building subject.”

Thank you for all of your kind words. 

There are days when I think what a joy it would be to be out building. I do truly love to build, smells of earth from freshly dug holes, lumber being taken out of a wrapped unit, sawdust – all of these give me warm, fuzzy nostalgic feelings.

I have kept myself in great physical condition and at 63 years-old I could certainly be out building. And I do know there are folks who would gladly pay my rate to have me do their construction. However this would allow me to properly assist only one client at a time. What I do now allows me to help thousands of people every year to get better buildings.

Enough of me waxing poetic – let’s get down to business!

(Side note – much of this advice is expounded upon in detail in previously written articles. Please visit www.HansenPoleBuildings.com, navigate to SEARCH at upper right corner, click on it, type in a word or phrase and ENTER)

Plan tips – consider these factors:

Direction of access (you don’t want to have to drive around your house to get to garage doors).

‘Curb appeal’ – what will people see as they drive up?

Any views? If so, take advantage of them.

North-south alignment – place no or few windows on north wall, lots on south wall.

Overhang on south wall to shade windows from mid-day summer sun If your AC bill is far greater than your heating bill, reverse this and omit or minimize north overhangs.

Slope of site.

Work from inside out – do not try to fit what you need within a pre-ordained box just because someone said using a “standard” size might be cheaper. Differences in dimensions from “standard” are pennies per square foot, not dollars.

Put up the largest building you can economically justify and fit on your property.

Plan for accessibility – 4′ or wider hallways and stairs, an ADA bathroom with a roll in shower. 3′ wide interior doors.

Walk-in (roll-in) closets for bedrooms, even secondary ones.

Consider if you truly want to live on a concrete floor. Crawl spaces are roughly the same investment.

Kitchen – two dishwashers, two microwaves, two ovens, trash compactor. Separate side-by-side refrigerator and freezer units. A good sized pantry.

9′ or 10′ finished ceilings in living areas.

Onto building construction itself….

Probably most important (and most often neglected) is proper site prep.

Make sure there is a vapor barrier under any slab-on-grade (and use 10-15 mil).

For slab-on-grade at least have pex-al-pex tubes run.

Personally I like flash & batt for walls – two inches of closed cell spray foam ideally with BIBs insulation to fill balance of insulation cavity. In this circumstance, you do not want a WRB, however you do want to order inside closures for top and bottom of every wall panel.

Order raised heel trusses so you can blow in fiberglass insulation to full depth from wall-to-wall.

For condensation control – use steel panels with Integral Condensation Control.

Vent sidewall overhangs and ridge.

Use all 5/8″ Type X sheetrock.

Make sure you and your contractor have a written agreement covering everything – it keeps feelings from being hurt and clearly outlines expectations. I will have a series of articles soon outlining some important inclusions for agreements, please watch for them.

Post Frame Building Insulation

Pole Barn Guru’s Ultimate Guide to Post Frame Building Insulation

When it comes to insulating any building (not just post frame ones – like barndominiums) there is a certain point of diminishing returns – one can spend so much they will never, in their lifetimes, recoup their investment.

Here my ultimate guide to post frame building insulation is based upon practicality and obtaining the best possible value for investment.

There are some basics applicable to any steel covered building:

Under any concrete slab on grade inside a building, place a well-sealed vapor barrier. Read about under slab vapor barriers here: https://www.hansenpolebuildings.com/2017/11/vapor-barriers-slabs-grades/.

Between roof framing and steel roofing – please do not assume condensation is not going to be a problem. At some point in time it will become one and if precautions are not taken regrets will happen. Condensation under roof steel is maybe number one of the issues I am asked to assist with.

Least expensive financially, but does take some extra labor hours, especially if it is windy – a single air cell layer reflective radiant barrier. Six foot widths will install much quicker than four foot. Make sure to order with a six foot width NET COVERAGE and an adhesive tab along one edge with a pull strip. Without an adhesive tab all butt edges will require seam tape, not expensive, but adds lots of time. Do not waste your money on adding an extra approximate R 0.5 for double bubble (two layers of air cells).

For a slightly great investment in materials, hours of labor can be saved by the use of an Integral Condensation Control bonded to roof steel. This would be my product choice. https://www.hansenpolebuildings.com/2017/03/integral-condensation-control/.

Next higher cost would be sheathing the roof with either OSB (Oriented Strand Board) or plywood on top of roof purlins. Roof purlins will need to be spaced appropriately so sheathing seams fall on purlins (16, 19-3/8 or 24 inches on center). Roof truss top chord live load must be increased to allow for greater dead loads. Either 30# felt (asphalt impregnated paper) or an Ice and Water Shield must be placed between sheathing and roof steel. Roof screws must still be placed to go into purlins, as thin sheathing is inadequate to adequately hold screws.

Bigger financial investment, but no extra labor involved is to have two inches of closed cell foam sprayed on the underside of roof steel. This will prevent condensation and is noise deadening. As a rough budgetary figure, plan upon spending roughly two dollars per square foot of roof surface.

Storage/Utility Buildings

If you ever believe anyone might ever have a future desire to climate control your building then provisions should be made for making it easiest to make future upgrades.

For now we will assume this building is totally cold storage. If it might ever (even in your wildest dreams) be heated and/or cooled include in your initial design, walls with a Weather Resistant Barrier (https://www.hansenpolebuildings.com/2016/01/determining-the-most-effective-building-weather-resistant-barrier-part-1/) between framing and siding. 

Taking walls one step further would be ‘commercial’ bookshelf wall girts (https://www.hansenpolebuildings.com/2011/09/commercial-girts-what-are-they/).

In roof – have trusses designed to support a ceiling load, ideally of 10 pounds per square foot (read about ceiling loaded trusses here: https://www.hansenpolebuildings.com/2016/03/ceiling-loaded-trusses/). 

Trusses should also be designed with raised heels to provide full depth of future attic insulation above walls (https://www.hansenpolebuildings.com/2012/07/raised-heel-trusses/).

Make provision for attic ventilation, by having an air intake along sidewalls using enclosed ventilated soffits and exhaust with a vented ridge.

Any overhead doors should be ordered insulated – just a good choice in general as, besides offering a minimal thermal resistance, they are stiffer against the wind.

Equine Only Use

Same as storage/utility however ventilation is essential (and often overlooked). (Read more on stall barns here: https://www.hansenpolebuildings.com/2012/08/stall-barn/)

Garage/Workshop/Man Cave/She Shed/House/Shouse/Barndominium

Many previous recommendations are going to be repeated here. Ultimately it is going to depend upon willingness to include higher R values in initial budget, rather than having increased utility bills forever.

Start with a Frost-Protected Shallow Foundation – post frame version (https://www.hansenpolebuildings.com/2016/11/frost-protected-shallow-foundations/) with sand on the inside rather than a thickened slab. This makes for an excellent and affordable design solution.

For walls, we will again work from generally ascending price and R values.

On low end would be having installed a weather resistant barrier beneath wall steel, in conjunction with commercial bookshelf wall girts. Fill insulation cavity with unfaced batt insulation and cover inside face of wall with a well-sealed six ml clear visqueen vapor barrier. As an alternative to fiberglass would be mineral wool insulation as it is not affected by moisture (https://www.hansenpolebuildings.com/2013/03/roxul-insulation/). This method can be entirely done D-I-Y.

I have personally used BIBs (https://www.hansenpolebuildings.com/2011/11/bibs/) in several buildings, including my current barndominium home. It does require a certified installer.

A Weather Resistant Barrier can be eliminated by the use of a ‘flash coat’ of two inches of closed cell spray foam against the inside of wall steel. Balance of wall cavity can be filled with batt insulation. (https://www.hansenpolebuildings.com/2016/07/advantages-spray-foam-over-batt-insulation/).

For added R value and a complete thermal break, add two inch rigid closed cell foam boards to inside of framing. To maintain thermal break integrity, glue foam boards to inside of framing and properly seal all seams. Gypsum wallboard can be glued to the face of foam boards.

After ceiling has been installed, have insulation blown into dead attic space, following Energy Star™ guidelines (usually R-45 to R-60).

Other I.C.C. Benefits

My last article discussed Integral Condensation Control (I.C.C.) solutions for steel roofing.

When Hansen Pole Buildings’ Designer Dave Gross constructed his own post frame building, I convinced him to utilize I.C.C. for his roofing. A testimony to how much he liked it – virtually every building his clients have invested in since has I.C.C.!

 Reduced Noise
A common concern for owners considering steel roofing is increased noise caused by rain and echoes. Steel roofing with I.C.C. offers significant sound deadening abilities, often decreasing rain impact and reflected noise levels by twenty percent.

Fire Rating

Most building codes require faced metal building insulation to have a flame spread rating of 25 or less and a smoke developed rating of 50 or less when tested according to ASTM E84 or UL 723. Steel panels with I.C.C. attached meet these standards.

Rot Resistant

The two components of I.C.C. are synthetic polyester fiber and rubber-based adhesives, neither of which is susceptible to decomposition from bacteria, mold or mildew. These materials are also well suited for cleaning with a hose or pressure washer in the event that they are soiled.

Additional Protection in Corrosive Environments

An unexpected benefit of this product is offered by its rubber adhesive membrane. The adhesive layer acts as a barrier which adds additional protection, isolating the washcoat of the panel from corrosive vapors often found in structures used for animal confinement. In light of this, an experiment was performed on bare galvanized and Galvalume® steel to determine the actual amount of protection offered by the extra layer. The experiment consisted of a 1000 hour test which exposed the interior of panels (with and without I.C.C.) to condensation from heated liquid manure. The results showed a clear indication steel panels are in fact shielded from the corrosive compounds. These findings strongly suggest panels with I.C.C. will offer a greatly extended service life in conditions which typically void the paint system warranties.

Planning your new steel roofed post frame building? If so, be like Dave. Dave is smart, his steel roofed post frame building doesn’t drip!