insulation for steel building house

[raymondtm]

I am finishing out a metal building that had the vinyl backed insulation at time of construction. I have studded out the inside, and am now at decision time for adding insulation. What are my options? I have attached a photo that shows existing vinyl and studs.
1. Considering spray foam insulation. Will it be ok to spray it onto the existing vinyl?
2. use traditional fiber glass batts?
3. other options?
4. and for any case, what is moisture/condensation considerations?

Since the photo was taken the electrical wiring has been done, door installed, recessed light installed, etc. I just need to decide about insulation.

Thanks all!

 

[PugetDude]

I've seen batts over foam, but never the other way around.
Hopefully Readhead or one of the other metal building contractors sees this thread.

 

[readhead]

On commercial jobs I usually see unfaced FG batts installed in the framing. If you are located in a high humidity area you may want to install a vapor barrier so you don't get condensation on the vinyl. It's to late now but if you had girts 2' on center then no framing would be required. That's a tip for the next guy.

 

[My Old Tools]

I did craft faced fiberglass batts over vinyl faced fiberglass wrap with a couple of inches of air gap in between. It worked out well and was cheap to heat and cool.
In the attic space I blew in cellulose. I'll never use that **** again.

 

[toyotadriver]

I built a house with metal siding. I installed 1inch foam sheets over the purlins and then screwed the metal on top of the foam sheets. I then had damp spray cellulose sprayed into the stud cavities. Very impressive insulation value.

Since your metal is up, I would insulate the walls with either damp spray cellulose or the blow in blanket system with cellulose.

I would NOT use fiberglass batts.

 

[raymondtm]

THanks, everyone. I have been told by a couple insulation businesses, and one foam insulation company, that I shouldn't blow the foam onto the vinyl backing. Any thoughts? And, 2, if that's the case, i'm back to installing fiber glass batts. That's ok, and will leave a few inches of air space between it and the vinyl. Is that problem, and should I put a couple vents in the top of the building eaves (like a traditional attic vents) to vent that space? I'm concerned a bit about the red iron sweating inside that air gap.

 

[My Old Tools]

Once it's insulated you won't have sweating. Mine had an air gap of maybe 2-3 inches between the vinyl faced insulation and the craft faced batts. My stud walls were built recessed under the wall purlin with no ventilation of the wall cavity. No problems. That trapped air gap adds to the insulation.

 

[raymondtm]

Thanks, Ross. I've thought that would be the case, also. But how would I ever know? My stud walls and ceiling studs are built on the inside of the purlins, as the pics show. I will have about 4" of air gap between batts and the vinyl along the walls, and about 6" on the ceiling. Maybe i'm worrying too much, but don't want mold to begin in the future.

 

[DC73]

THanks, everyone. I have been told by a couple insulation businesses, and one foam insulation company, that I shouldn't blow the foam onto the vinyl backing. Any thoughts?

Not sure about that. There is a difference in open cell foam and closed cell foam. I certainly don't see an issue with spraying closed cell foam (which is already an effective vapor retarder) against the vinyl backing. Open cell foam is more vapor permeable.

I'd run the question by the gurus on the Q&A forum over at GreenBuildingAdvisors. They should know for sure.

DC

 

[francisharvey]

This gave me some ideas in insulating a metal-sided bldg. http://metalbuildinghomes.org/metal-building-insulation-options/
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