New guy with insulation questions.

[brownie088]

Hey guys. Just joined GJ. Recently had a 36' x36' x12' high pole building constructed. concrete and driveway done. Getting ready to insulate and install electric. I want to use rigid foam board against purlins between posts, then cove with osb or drywall. Anyone done it like this? I have had some people tell me they cut foam board and put between purlins against steel siding. I am not sure if that would cause a condensation issue. Running electrical on outside in conduit. Any suggestions on foam board install? Need an interior vapor barrier? Thanks. located near Annapolis Maryland.

 

[brownie088]

Also , I have been thinking of using mineral wool or rock wool bats in the walls. Anybody use this?

 

[theoldwizard1]

Here is what I would do.

Higher a spray foam company and have them do 1-2" along the edges of all posts top to bottom and all "joints". Along the edge of any wood where a fastener to hold the tin has penetrated. If they do a good job, you will have a very moisture resistant, "tight" building. This will help a lot

Cellulose is typically the lowest cost insulation material. "Wet" cellulose can be sprayed on to the tin, but applying 1-2" foam board first would be better. With wet cellulose you have to install an inner wall within a few days or the stuff will dry out and fall off.

Wet cellulose usually require a professional to install it, so price it out. You can do dry cellulose yourself (home centers will rent you the equipment), but the interior wall must be in place and then you will have to cut holes to blow the cellulose in. Still very cost effective/DIY, just a bit more work.

Mineral wool is expensive and is not much better of an insulator than cellulose or fiberglass. It IS great at cutting noise !


P.S. Purlins go between/on top of rafters. Girts go between/on top of posts.

 

[brownie088]

Thanks for the reply. I got a quote for spraiy foam. Still need to decide if I should just do it or not...money is the issue. I can get a good deal on used polyiso board. If I go just foam board route, should i go over the girts? Or cut and fill between them? And can they touch the outer metal? Very humid in summer here...