This week readers “ask the Guru” about reroofing a pole barn with shingles, ventilation or new roof, vapor barrier to insulate properly, and insulating an existing pole barn without spray foam.
DEAR POLE BARN GURU: We have a pole barn it was purposely built to have an apartment upstairs; it originally was a stable below. It’s all living quarters now. We have had issues with the steel roof. We are switching to class 4 shingles. The building has no eaves as it has porches off both sides. We are working with a roofer. They are suggesting we use some ridged vent at the lower edge of the roof, by cutting a notch in the edge and installing it under the shingles and decking. That’s my understanding. Also, it will have a full ridge vent. The steel was applied on decking with tar paper under it. We have had leaking and condensation with it, as it is. Just wondering if you have any other ideas, or if the ridged vent at the lower edge of the roof will be a problem? It has 16″ deep trusses with blown in insulations above the sheet rock ceiling. Thanks for any input or ideas. JENNENE in RAPID CITY
DEAR JENNENE: In my humble opinion, shingles of any sort are a poor investment. This is why: https://www.hansenpolebuildings.com/2018/10/ask-the-builder/
Installing steel roofing over “tar paper” was probably not a best design solution. A synthetic underlayment would work much better.
Call me a skeptic – I just do not believe you will have adequate air intake from vents as described. While gable end vents are not an ideal solution, they can at least be sized to afford adequate air flow. Here is what you should be looking at creating: https://www.hansenpolebuildings.com/2018/03/adequate-eave-ridge-ventilation/
If you have attic condensation currently, it is due to one or both of – improper/inadequate ventilation and/or not having proper exhaust ventilation inside your home. You may very well need to mechanically dehumidify to resolve this issue. As your building’s original purpose was to be a stable below, chances are good there is not a proper vapor barrier under your slab on grade. If so, this is further compounding your moisture issues and you may want to look into sealing your floor.
DEAR POLE BARN GURU: I’m in the middle of designing my Post Frame shop. I’m planning a 48’x64’x16′. I’m in climate zone 4a. I’ve been researching vapor barrier, radiant barrier and house wrap. I’m getting mixed info on the internet for my zone. Do I use vapor barrier? Can I use perforated radiant barrier in vapor barriers place? Where do I put it? And do I install it on the bottom of my trusses for blown in insulation? Hopefully my questions make sense. Thanks for any help at all. Respectfully, JUSTIN in LONDON
DEAR JUSTIN: In most instances a reflective radiant barrier is a waste of your hard- earned dollars. They can be (when properly sealed) an excellent vapor barrier, however using a perforated product takes away even this as a possible benefit. Walls – from out to in…. Siding, Omnidirectional housewrap over bookshelf wall girts, fill entire cavity with Rockwool insulation batts, well-sealed clear poly vapor barrier, interior finish. Roof – Order raised heel trusses (at least an inch taller heel than depth of blown in fiberglass (not cellulose) insulation). Order roof steel with an Integral Condensation Control factory applied. Vent eaves and ridge in correct proportions. No ceiling vapor barrier.
DEAR POLE BARN GURU: I have an existing pole barn on property that I would like to insulate. I would like to steer away from spray foam but am worried as there is no Tyvek or vapor barrier on external side. What are my best options to void off any moisture issues and create a well insulated wall. JAMES in LAKE VILLAGE
DEAR JAMES: I would remove siding a wall at a time, place an omnidirectional building wrap over framing, then reinstall siding. Fill insulation cavity with Rockwool batts and use a well-sealed clear poly vapor barrier before interior finish.


DEAR ROBERT: All of these recommendations are based upon meeting energy code requirements for conditioned buildings. Washington State will be a stickler for these.
DEAR POLE BARN GURU: What size posts should be used for 30′ x 40′ x 10 with 6/12 pitch in southern lower Michigan??? Storage/ garage / shop. STEVE in MARSHALL
“I read your blog often and I truly appreciate the wealth of knowledge you openly share. I am in the process of starting construction on a hybrid steel shop that will house a small apartment that the wife and I will move into once its finished. We will sell our current home and then build a smaller house adjacent to the shop. 50 X 80 with 24′ wide mezzanine on one end. My questions are centered around wall/roof construction as well as proper insulation. Roof: I plan to install a standing seam roof with ice/water shield over 5/8 plywood. As you are aware, with hybrid steel it is hard to ventilate the roof with this type of construction. This downfall didn’t outweigh some of the benefits so this is what I am stuck with. Would like to understand some insulation options. Note: I do have the building designed to handle the loading of a couple of cupula’s and have considered making these passive and active ventilation points. (Exhaust fans with some louvers that I have yet to get the details figured out on)Walls (2 options): (Note: I prefer not to plan or have to always be fully conditioning the shop to 72 degrees…..I plan to have that ability by mechanical means but I don’t want to consistently have to be conditioning that much space, therefore I think i prefer the building to be able to breath out to the perimeter. I realize this may be tricky between the roof type and wall type)Option 1: metal siding – would like some input on wall and insulation construction based on the above notes of conditioning. Option 2: Hardie board vertical board and batten walls. Same as above, would like your input. There will be components on the first floor and second floor that make up the apartment space. Our approach on insulation and wall construction may change within those enclosed spaces may vary as they will be conditioned separately from the open shop space. Hope you can help shed some light on this approach and again thank you for your time and knowledge. Thanks!”
Thank you for reaching out to us. I also qualify for those senior discounts and fully understand stair issues. When we built our own shouse (shop/house) in Northeast South Dakota 15 years ago we went with two stories and my lovely bride insisted upon having an elevator (we actually now have two of them).
DEAR POLE BARN GURU: When installing horizontal sheeting, does the top sheet always cover the bottom sheet when joined? GARY in EUFAULA
DEAR POLE BARN GURU: 
The structural system of a post-post frame home, its engineered plans and foundation are all going to prove to be less expensive than stick frame. Everything else is going to be pretty much the same – cabinets, fixtures and floor coverings do not suddenly become less expensive just because they were in a post frame building.
DISCLAIMER: This is NOT a Hansen Pole Building
Welcome to Ask the Pole Barn Guru – where you can ask questions about building topics, with answers posted on Mondays. With many questions to answer, please be patient to watch for yours to come up on a future Monday segment. If you want a quick answer, please be sure to answer with a “reply-able” email address.
TextraFINE® Post Frame insulation is made from inorganic silica sand which is formed into long textile-type glass fibers which are bonded together in random orientation by a stable thermosetting binder. This process produces unusually strong, resilient insulation which will return to full thickness following compression.
Foam board insulation is commonly placed against the steel building siding, between the girts of exterior walls. To prevent air infiltration, place rigid insulation boards tightly together and seal the seams with tape or caulk. This practice may worry some in cold climates since the foam board may act as a second vapor diffusion retarder. Studies have shown, condensation rarely occurs in these areas unless something else is seriously wrong with the wall assembly (like massive uncontrolled air leakage into the walls from the building). If the assembly is constructed correctly, the inside surface of the foam board stays warm enough to keep water vapor in its gaseous state long enough for it to escape.