Today the Pole Barn Guru answers reader questions about moisture control, insulating a building with a ridge vent, and a solution for replacing posts that have rotted out.
DEAR POLE BARN GURU: Thanks for the abundance of technical information you provide your readers. Like many of them, I inherited a pole barn with the same ceiling sweating, heat, cold issues and need a post construction solution. The slab sweats only in some places. I have a typical wood post with 2×4 horizontal purlins, wood truss and purlin roof, and metal skin walls and roof. My goals are, #1 stop the moisture inside, #2 insulate for moderate comfort (no codes to comply with and I can heat with a wood stove and abundance of wood) , and #3 if I can afford it, skin the walls with T-111 or other wood for an attractive look inside. I did not see any suggestions about double-faced radiant barriers in your other articles. Do you think expanded polystyrene cut to fit in the 1.5 inch cavities to flush with purlins, and then add the radiant barrier (bubble type) stapled over that directly to purlins would be appropriate and not trap moisture? If so, should I allow and air space between the polystyrene and radiant barrier? Many thanks, Mr. Retired…finally! JOHN in CHEROKEE VILLAGE
DEAR JOHN: Thank you for your kind words. If your slab sweats at all, it is likely there is no vapor barrier under it and it would behoove you to apply a sealant. 1.5″ expanded polystyrene (EPS) boards cut to fit tightly and with all seams tightly sealed would give you some degree of insulation (roughly R-7.5 other than at girt and purlin locations). You could add unfaced rock wool batts to increase insulation. Radiant barriers provide next to no insulation value and only function if seams can be perfectly sealed, we’ve actually opted to no longer offer them to our clients.
Unless you want to heat area in triangle of trusses, you may want to consider insulating at ceiling level, then vent dead attic space above.
DEAR POLE BARN GURU: Hello Mike. I came across your website while trying to learn more about what to do with the ridge vents in a pole barn when you plan on insulating it with closed cell foam. My wife and I purchased a property that has a 36w x 48L unconditioned pole barn with 8 skylights, a couple of ridge vents and (2) sets of huge doors on each end. While we know this will never be a tight building, we need to insulate it for our pets (10) dogs and (11) cats, and for a hangout area for us to spend time with them rather than inside our home.
We have a high-end American Standard heat pump split system that will condition the entire space.
Would you be able to give me any advice on what you recommend I do regarding the existing ridge vents? I’m not sure if I should insulate around them and leave them as they are…open. Or, should I temporarily trim out around them and seal them for the time being?
Any information you could provide me on this topic would be greatly appreciated. ROGER in HOUSTON

DEAR ROGER: With those large sliding doors, your investing in closed cell spray foam may be for naught. If your expectation is to be able to control any sort of heat loss/gain you should consider replacing them with insulated steel sectional overhead doors.
On to your question – seal off ridge vents and spray foam across skylights (or, even better) replace them with steel roofing before insulating.
DEAR POLE BARN GURU: What are my options on repairing 32×40 all 6×6 posts are rotted off ground level. Floating slab, perma colum, helical peir, or strongway sleeve. CHAD in GREAT BEND
DEAR CHAD: I would repair one column at a time. Temporarily support roof system being supported by a column. Cut column off above point of decay. Excavate embedded portion of column and remove – hole being dug to be at least below frost line. Insure bottom of hole is firmly compacted. Place a sonotube in hole, attach an ICC approved wet set bracket to bottom of column and backfill with premix concrete. Compact granulated fill around sonotube in six inch lifts. Repeat at each column.
DEAR POLE BARN GURU: Hello again Mike, Our Southern MN town is planning to add an open- air pavilion to a city park and the talk is a heavy-duty concrete pad that would have embedded attachment for the support posts for the roof (presumably steel). The thinking is for a post beam type spec about 30×48 in a park that does NOT have any open lanes for wind. It seems to me the Hansen type of post installation with concrete below and around the post that both supports the weight and serves as anti-lift makes economical sense by requiring less forming and pre-mix costs. PLUS, a certified design that accounts for MN snow and prairie wind exposure would be prudent. (I am assuming your engineers will adapt the construction design to not having metal walls transfer roof loads to the ground.) I will also be recommending to the city to consider adding a partial enclosed area for restrooms and winter warming house for the nearby ice rink that goes over basketball and pickle-ball courts. Thanks for any suggestions or examples you have. BRIAN in LE ROY
DEAR POLE BARN GURU: Okay… two things. In my quest to find what’s correct, hearing it both ways: live in Iowa. It’s both: cold in the winter, hot in the summer, humidity fluctuates. In my 12×40 addition on my 40×40 pole barn it rains inside daytime in the winter. Because the sun heats the steel. I want to Insulate (rockwool) the 40×40 and heat it: (forced air through water/air radiator, outdoor wood fueled boiler) According to most I put a vapor barrier internally. OK, but the sun is still going to heat the steel and cause moisture in the insulation is it not?? So should the vapor barrier be on the outside?? Secondly: yeah, this house. I hate it. Built in ’76 the old man put sheet plastic over the fiberglass insulation already a vapor barrier. The few places I’ve had to remove drywall I’ve found mold on the back of the drywall. JEFFERY in BLOCKTON
DEAR POLE BARN GURU: My pole barn roof installer missed the purlins with about a third of the screws. His fix was redrive the screws at an angle to catch the purlins and smear some caulk in each screw. I’m pursuing some genuine relief. I’m now concerned the metal seals on each of these angled screws has permanently deformed the roof steel under and around each of these angled seals so that not even a properly straight driven screw will seal in each of these locations. How legitimate is my concern? BOBBY in LINCOLN 



DEAR GREG: Sounds like you are creating a dead attic space. You should order roof steel with a Integral Condensation Control (
DEAR RON: Unless you are going to mechanically dehumidify, expect to see condensation challenges.
DEAR POLE BARN GURU: Can you add a 16 ft wide garage door to an existing pole barn? It would be on a gable end of a 30×50 building. ALEC in TOLEDO