Insulation for carport type shop

[Joe Shinall]

I built my shop by enclosing in a 16x20 metal carport. The walls are studded in and insulated with OSB over them. I was wondering about insulating the roof. My only option that i know of is using the pink insulation foam sheets and glueing them to the underside of the metal with some construction adhesive. More than anything, I'm looking for some soundproofing but would be nice to keep the A/C inside the shop too this summer.

Is this a good idea and my only hiccup I can think of is that in the winter time, the roof sweats on the inside. Would this still happen with the insulation up? Don't want it to get trapped between and cause mold.

[Charles Lent]

A friend tried gluing his foam insulation panels in place to his metal carport converted into shop roof, and much of it came loose the first year. I think he used the regular caulk gun construction adhesive. After much of it came loose, he then put up wood strips cross wise, attaching to the metal beams, in an effort to hold the foam insulation in place. If I had to do it I would attach some wood strips cross wise to the metal beams like he did, but then attach the insulation to the under side of the wood strips. This would leave an air gap between the metal and the insulation that should help keep the shop cooler too. I think the heat of the Sun changed the size of his metal roof enough to break the glue bonds in his direct contact method, but maybe a more elastic glue like maybe RTV Bathtub Sealer would allow more flexibility in the glue bond, although I don't know how you would keep the panels in place while the RTV dried. My friend died 2 years ago, so his shop insulation project was never completed.

Charley

[Joe Shinall]

My condolences on your friend Charles. That is a great idea though to leave the air gap between and use the wood strips.

My only concern, still, is the roof sweating and possibility of mold. between the 2. If the insulation will stop the roof from sweating, then problem solved....

[Paul F Franklin]

The only sure fire way to keep it from sweating is to keep moist air away from it. or keep is so well ventilated any moisture is carried away. If you do a really good job with the insulation and tape all the seams and caulk any gaps, it could work, but it would be tricky on a sloping roof.

A alternative would be to have it spray foamed. On an open area it's fast and easy to do. Gives you good insulation and completely air seals so no chance for moisture to form on the steel. But (there's always a but) the foam has be covered with a fire barrier, or you have to use special (and more expensive) foam with a fire rating.

Any possibility of building a high ceiling and insulating above that? You would ventilate the air space above it like a typical house attic.

[Joe Shinall]

Paul, I actually looked into spray foaming tonight after I posted this. I have a couple of emails out to get some quotes.

There's no change of doing a ceiling. Way too much work to undo everything I have done already including electrical and lighting and I really love these high ceilings in it now.

Thanks for the tip on the fire barrier. I'll ask about the foam with the fire rating and see what they say.

[Rollie Kelly]

Joe, if sound damping is your primary concern, Roxul is the product of choice. The foam will be the least effective. Pink fiberglass will result in only be a moderate improvement. If you Google sound damping, you will find more info than you might want.

As far as thermal performance, they are pretty well on a par. However, don't forget "bubble wrap" type insulation.

Hope this helps and good luck,
Rollie

[Joe Shinall]

Good tip Rollie, will definitely look at that. I am definitely more interested in soundproofing over insulation. I will do some research on Roxul tonight. Thanks!