Spray foam and finished interior - what's your setup?

[brianpgriset]

about to sign papers on a new shop.

30x60x14, stick built, 2x6 walls, 2ft truss spacing on roof, metal panel exterior, plain and eaves with no soffits, vented ridge cap.

I want to finish the inside with drywall or osb on walls and drywall or metal panels on ceiling. Want to run electrical in the walls.

First plan was to do batt walls and blown in insulation on the ceiling but with no sort of soffit vent I was worried about moisture. I like the idea of foaming the entire thing but I see two problems I wanted to ask about:

1. Has anyone foamed a wall cavity but left enough room to still run eletrical? IE I get three inches of foam in the wall bags which still leaves enough room for running wire, then finish over that. Is this OK?

2. I want to put up a ceiling. Can I just put up a ceiling with no vents to the attic? I plan to add air conditioning but not run it 100% of the time, maybe only 30 or 40%. Will this cause issues?

If you have a spray foamed building with a fully finished intdrior, could you share your setup?

Thanks.

 

[Black Oak]

Why no soffit venting ? Attic spaces in Texas will be very hot , metal roof or shingle . To see benefit from the ridge vent you'll need an intake point somewhere . I'd run at least a 36,000 btu Mini Split . They don't cost a fortune to run . Mine runs 24/7 .

 

[PCMusicGuy]

Any reason not to run electrical first and then foam the whole thing, walls and roof? If everything inside the roof and walls is foamed I don't know that you need venting at all. If you make the entire envelope of the building conditioned space, you could do whatever you want with the interior ceiling.

 

[brianpgriset]

Why no soffit venting ? Attic spaces in Texas will be very hot , metal roof or shingle . To see benefit from the ridge vent you'll need an intake point somewhere . I'd run at least a 36,000 btu Mini Split . They don't cost a fortune to run . Mine runs 24/7 .

I honestly have no idea but NONE of the metal buildings here have it. Yet I see many with ridge vents. I asked the builder what most people do who finish the inside such as barndo's and he said spray foam.

 

[brianpgriset]

Any reason not to run electrical first and then foam the whole thing, walls and roof? If everything inside the roof and walls is foamed I don't know that you need venting at all. If you make the entire envelope of the building conditioned space, you could do whatever you want with the interior ceiling.

I'll probably do electrical first but I want to be able to add/change things later. I plan to be in this shop many years (hopefully).

Surely if have to have some kind of vent to the space above the ceiling? I could leave it open but I don't want to see the foam or exposed truss members.

 

[mike93lx]

You could have 2" of closed cell sprayed and then add fiberglass or mineral wool Batts to fill the cavity. It would leave plenty of room for electrical

 

[nadogail]

I would run electrical first and then the insulation. Much easier to wire an uninsulated space.

 

[yeldogt]

The attic of a fully foamed building is not hot -- it's part of the conditioned space ... just the leaks through the ceiling will condition it.

People don't understand how much a traditionally insulated building leaks -- venting an attic space -- ***** conditioned air or pushes unconditioned air into the structure.

Normal to run wires and then spray