This Wednesday the Pole Barn Guru answers reader questions about what trim to use on building corners, an issue of installing metal to roof that is extremely out of square, and best options to insulate a building.
DEAR POLE BARN GURU: Good afternoon! Looking to see what trim to use on the corners? https://www.hansenpolebuildings.com/2015/10/horizon-steel-siding/ Sincerely, KYLEIGH
DEAR KYLEIGH: Order standard Corner Trims and place pre-formed foam Outside Closure strips between horizontal steel siding and trims.
DEAR POLE BARN GURU: How much more difficult would it be to put the metal roof on if you can’t square the roof trusses. Because the posts were not cemented in properly. We are 8′ out of square on a 24’x50′. Would it be possible to square being that far out? TOM in BLOOMSBURG
DEAR TOM: I want my roof planes to be square within 1/8th inch before attempting to run steel. At 8′ out of square, I would have pulled out all offending posts and started over again. What you have will be impossible to properly roof and would require cutting every sheet of steel at eaves to even get a straight overhang line.
DEAR POLE BARN GURU: Just finished 40x60x16 pole barn and am looking to insulate. Building wrap was installed on exterior walls and roof has double bubble. Wondering how to manage moisture inside the building. Slab is insulated under as well as a vapor barrier. Interior walls and ceiling will be finished with steel liner panel. I’d like to spray foam entire building with open cell spray foam walls and roof deck. Would I need to install a vapor barrier between foam and steel liner panels? Building has attic trusses and the room will also be conditioned separately from garage space. Thanks KYLE in COXSACKIE
DEAR KYLE: I would not spray foam to building wrap, as it causes more problems than it solves. https://www.hansenpolebuildings.com/2020/04/spray-foam-insulation-3/
For walls, I would use unfaced rock wool batts, with a well-sealed interior vapor barrier. You do not need a vapor barrier between ceiling liner panels and attic spray foam. Personally, I would blow in fiberglass above ceiling liner panels and ventilate the dead attic space.
It might be necessary to mechanically dehumidify your building.
Insulating an Apartment in a Steel Truss Pole Barn
Reader JONATHAN in AUGUSTA writes:
“First of all, thank you for having a wonderful resource put together in one place for fellow DIYers such as myself. I am currently in the process of constructing a 30x60x11 pole barn. So far I have the roof put up; metal trusses with 2×6 wood purlins, synthetic underlayment and metal R panel. I will be building a 30×24 “apartment” inside, think box inside of a building with the remainder being used as a shop. 3 sides of the apartment will be the exterior walls of the pole barn with the 4th side splitting the barn almost in half. I will have mechanical ventilation in the form of an exhaust fan cut into the side of the building sized to the 30×36 portion with an appropriately sized louver that I intend on using when necessary when working in the shop. The apartment will have HVAC. I am looking for the best method to insulate the roof. Vented/unvented? Spray foam? Radiant barrier nailed to the bottom of the purlins? I plan to house wrap the walls and install Rockwool to insulate them but was unsure about the roof. There are so many conflicting methods out there I just want to get it right the first time. I am in a hot humid part of the south. I look forward to your thoughts on this and thank you in advance for any advice.”
Mike the Pole Barn Guru advises:
Thank you for your kind words. Obviously we are somewhat self-serving as many of our blog readers understand Hansen Pole Buildings caters to those who want to DIY and realize there is a good chance we can assist them in reaching their ultimate goals, without undue road bumps and pot holes.
You have some challenges happening here (aka pot holes), in part due to your choice of roof systems. Those trusses are not designed for a ceiling and 2×6 roof purlins at this span will deflect too far to allow for sheetrock to be applied to them, or to give an adequate depth insulation cavity.
If I was in your position, I would frame in 8 or 9 foot tall walls for apartment area, with ceiling joists above. I would then use unfaced rock wool batts between ceiling joists to R-30 (Climate Zones 0 and 1) or R-49 (Zones 2 and 3). Use 5/8″ Type X sheetrock for apartment ceiling and wall between apartment and shop (personally I like 5/8″ everywhere).
Ventilate balance of building otherwise you will most probably experience condensation challenges.