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Discussion Starter · #1 ·
Trying to insulate a pole barn - metal roof. Current walls are t-111 - I will be pulling them off and putting something else on - not sure what yet.
For the roof, I want to insulate it a bit. When it is cold and I put on the heat, I get dripping from teh ceiling. I am told if I spray foam it, I will get some insulation, and no water (and less noise). I had considered just putting up rigid foam board (putting a small cleat on the trusses to hold it) with a slight 1/4 air gap to all ow for air to flow and water to run off. Any comments, thoughts, ideas? The building currently has no heat other than the torpedo heater I put on for the few times I am in there. Long term plan is propane heater to be used when I am in the building.

I would blow off insulating it, but the condensation on everything is a pain (yes, another member warned me). If I can close it up better, I think it would be more comfortable, and less "wet" when it is not occupied.

Also, in case it's related - the floor is smooth concrete - I have thoughts of putting down epoxy on it (down the road).
 

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spray foam would probably be the best bet , but I am not too familiar with it ( I believe you would get some outgassing also ) Rigid can be funny sometimes as far as condensation , you definitely need a airspace for air to circulate from top to bottom of the run .
 
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The reason for the water dripping from the ceiling when you put the heat on is because the building is not properly vented. Spray foam will not help this it may make it worse. First you must vent the roof and the soffit to have airflow. Install baffles or create an air space between the insulation and the roof and then insulate. Condensation will rot the rafters and destroy the roof from the inside out.
 

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I have seen condensation off of both spray on insulation as well as rigid directly on the metal roofing. I suggest you address the real issue, which is ventilation. an airgap between the rigid insulation and the metal, or a horizontal ceiling that is insulated on the top side.
 

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Depends on the roof design also . Do you have rafters and horizontal strapping ? There could be a number of different configurations ( I know , I am building one in Vt. now )
 
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I am assuming that you have a metal roof mounted on roof purlins(run across the trusses), and not on top of wood sheathing correct? If this is the case, your time for foam boards really has passed. The boards should be sandwiched between the metal and the roof purlins. This way it provides a small amount of R-value, AND acts as a shield to let any condensation run down to the soffit facia to drip off of the edge. See mine in the picture. Adding panels in between the trusses now is going to be a pain in the butt(but possible). Spraying foam directly to the underside of the metal may not help either(and expensive). You may want to just enclose the ceiling by running stringers across the truss bottoms, and hang a insulated ceiling. Your roof should be properly vented at the top with a ridge vent, and maybe add a couple of larger vents at the gable ends. Good luck, and please post your results.
 

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you can still put rigid if framed as above , 2 ft. or 4 ft OC rafters . Here's how .

You attach a spruce 1 x 2 against the purlins along the side of the rafter ( this creates an airspace from top to bottom ) Then you put your rigid against the 1 x and sandwich with another 1 x . Purlin , 1x , rigid , 1x . I would make a test of this and watch it for awhile .
 

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Discussion Starter · #8 ·
you can still put rigid if framed as above , 2 ft. or 4 ft OC rafters . Here's how .

You attach a spruce 1 x 2 against the purlins along the side of the rafter ( this creates an airspace from top to bottom ) Then you put your rigid against the 1 x and sandwich with another 1 x . Purlin , 1x , rigid , 1x . I would make a test of this and watch it for awhile .
Yes, this was my plan - rip down some 2x4's to make trips to use as a spacer above and a "cleat" below. Cleat would hold the foam board up.

In my case, the ceiling is open - like in bigbore's picture. It is not so much of a ventilation issue per se. It starts as a cold dry room. If I go in there and work (with everything closed up and heat running), the moist warm air rises to the roof, and then the moister condenses when it hits the cold steel roof. I could vent the whole place with eve vents, but then I'm blowing warm air out the building all day (with little chance of the place getting warm).

True, the last time I worked in there, it was raining out (hard) and the vehicle I rolled in to work on was soaked. I know it's hard to keep moisture off cold things (like a metal roof) - so I thought the spray foam would do the trick (and I would not have to worry about managing the water running off the metal)
 

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You want the air behind the foam to come in at the bottom of the run and escape at the top . It can't be captive . And like I said there are multiple variables with these applications so each job is somewhat unique .
 

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Recommend Open Cell over Closed Cell, Do not put either against standard OSB if you can help it, As others mentioned make sure you have good venting. IMHO, I am not a fan of spray foam, No one knows the effects of it on the occupants all that is known is that it off gasses. You can get the same R value and seal job with a $1,000 caulk job and regular insulation, I think spray foam is a waste of money
 

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That Guy
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Any pictures.
 

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Discussion Starter · #12 ·
zzrguy - you are waking the dead (lol) - Sorry I never posted completed pictures. It was a bit of a pain in the butt, but I have kids, so I made them do most of the work (after all, why else would one have children, except for their usefulness as slave labor?). Here is a crappy photo of the before and after.

Shelf Bookcase Wood Publication Shelving

Aircraft Vehicle Airplane Aviation Beam

I cut the rigid foam fairly close to bay width (using table saw), and then foamed the edges (tried not to let foam touch metal roof - so there is some outlet for water). Perlins were not run exact, so this made for more work.

The insulation worked. No more rain...
 

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That Guy
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Cool good to here it worked out for you.
 

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I have an existing pole barn with a metal roof. 2x10 rafters 19.2 centers with 2x4 purlins 2' centers similar to bigbore44 picture above. I am retrofitting for engineered structural sheer in a high wind area. all exterior walls (currently open, no walls) to be 1/2" sheer ply and installing a complete sheer ply ceiling. I am concerned about condensation from warmer moist air hitting the metal roof. If I install bat insulation in the 19.2" cavities I don't want to get it wet and loose my R value or rot the rafters. The cavity will be inaccessible after the sheer ply is installed. There is existing venting at the ridge and planning venting at the eves, concerned that in NC coast that the humidity is very high and condensation will be a problem. I considered installing a 1" or 2" ridged foam board with sealing edges and r-19 (18" x 5 1/2" batts) below it in the 2"x10" cavity ( 9 1/4" space) leaving room for air flow to ridge. The foam board would be a vapor barrier. This project is very labor intensive.

I have considered spray foam on back of metal roof but very expensive and comments above has me questioning the spray foam installation.
 

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Discussion Starter · #20 ·
Amazing - A guy tries to hijack a three year old thread with a push for a Florida based roofing company - on a "LONG ISLAND firearms" forum.

So...should I ever buy a house in Florida, AND have roof problems, I know who not to call.

And if Marcus sees my "mini rant", don't think "he is just being pissy about it" - I'm not. Really just trying to remind people of what used to be called "civility" and now we call them "rules".

I'm a real estate agent. If I met you someplace, and you mentioned you had a problem at your hosue, I wouldn't go with, "well, the house had probably gone to crap. Probably time to sell it. I can help you sell the house and buy a new one. Let's do that right now." That would be RUDE. Back in the day, a friend, coworker, or family member would quitly tell me - "Don't do that...it's rude...you just seem like a pushy bastard that wants to make money."

Actually, looking back at the post, it looks like you hired a company to randomly go out, make accounts, and post to foums trying to work in your company name and website. You probably paid at least $3 per placement, and in this case you went with a company that didn't know that the "516" area code was nowhere near the "561" area code. If you email them to compain, tell them, "it's like advertising in Mumbai for a business in Chennai" (you gotta keep your examples local to covey meaning...)
 
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