Tag Archives: Climate Zone 3A

Insulation/Envelope, Egress Window in Gable, and Ribbed Steel Testing

Today’s Ask the Guru tackles reader questions about how to best insulate/envelope a pole barn shop in AZ, if the Guru has “an engineered work around for gable ends so I could replace the vent with an egress window,” and trying to find out if pole barn ribbed siding is tested under NFPA275 to be used to finish the inside when the walls are spray foamed.

DEAR POLE BARN GURU: Hello, I am currently being approved from my lender to build a 30’x40’x10′ pole barn shop. I will have 12″ eaves with soffit vents. The shop will be climate controlled 365 days a year. I am getting lots of different advice on insulation/building envelope. I wanted to get your opinion. I do not think spray foam will be in my budget. Could I use Tyvek wrap with fiberglass batts in walls and blow in fiberglass in ceiling? Or should I use something like Solarguard under the roof, and Tyvek on the walls. I would appreciate any suggestions you may have. I want to get this build right. If you could send me your reply to my email that would be great! Thanks so much. SHAWN in NOBLE

DEAR SHAWN: Noble is in Climate Zone 3A, where I would not typically have recommended spray foam insulation anyhow. Roof – Solarguard is not insulation. Order roof steel with an Integral Condensation Control factory applied (Condenstop or Dripstop are a couple of brand names of I.C.C.). Blow in R-49 fiberglass or granulated mineral wool (best), above ceiling, using raised heel trusses to get full depth of insulation from wall-to-wall. Ventilate eaves and ridge. Walls – Housewrap between steel siding and bookshelf wall girts. Unfaced R-20 (or greater) batts either fiberglass, or better yet mineral wool, with a well-sealed interior vapor barrier. Slab – if not doing radiant in floor heat, use R-10 rigid insulation on inside of pressure treated splash plank, from top of slab down two feet. If using radiant floor heat, then R-10 at slab edge and a minimum of R-5 continuous under slab.


DEAR POLE BARN GURU: Do you have an engineered work around for gable ends so I could replace the vent with an egress window? BRUCE in GOLDENDALE

DEAR BRUCE: It is likely it can be done however it may require other structural modifications in order to not compromise shear integrity of your endwall. You should reach out to a competent local Registered Professional Engineer who can do a physical site evaluation and then design a proper structural fix.


DEAR POLE BARN GURU: I’m a bldg. inspector and we’re trying to find out if pole barn ribbed siding is tested under NFPA275 to be used to finish the inside when the walls are spray foamed and if so is there a certain gauge that is only approved? Thanks ROBERT in ALBERT LEA

DEAR ROBERT: Ribbed steel siding does meets UL 790 Fire Resistance Class A requirements, however I am not finding any evidence of testing to prove it meets NFPA 275. I did find evidence of IMP (Insulated Metal Panels) with 26 gauge interior facings probably meeting requirements, however it would be up to the individual Code Official to make a judgment as to whether, in their opinion, 26 gauge panels would be adequate. https://www.metalconstruction.org/view/download.php/online-education/education-materials/imp-educational-materials/fire-safety  In my humble opinion, best practice would be to use an intumescent fire proof paint on interior surface of spray foam, prior to installation of interior steel liner panels.





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.