How to insulate the underside of metal sheet roof?

[Mskayladog]

To stop condensation. Could I use spray insulation and a brush to smooth it out so its more like a pain job?

 

[ailurophile23]

Seems like the spray insulation might work. How about using the R-board insulation panels? If you could attach them to or inbetween the rafters, that should help too. Or even adding the stuff that looks like foil covered bubble wrap.

 

[Folly's place]

Whatever you use, if the birds can reach it, or rodents can get to it, they wi;ll chew it up. Mary

 

[Bear Foot Farm]

If you brush it out, you lose all the insulation value

 

[cowcreekgeek]

To stop condensation. Could I use spray insulation and a brush to smooth it out so its more like a pain job?

I've often used the closed-cell polyurethanes (triple-expanding foam) as essentially a glue to bond materials directly to metal panels, as I've yet to see it release it's grip -- acetone is about the only way to get it off. You only have a few seconds of working time w/ this stuff, so dry-fitting and double-checking is required.

If you go with styrofoam, then don't use common construction adhesives, as they contain solvents that will melt your insulation. For example, PL 200 will burn right into it, but I've used Loctite PL 300 VOC Foamboard Adhesive for years to glue styrofoam to wood surfaces.


A thought here is that you might be better off to use a vapor barrier on the rafters, so as to prevent warm, moist air from reaching to cold metal surface, but allowing a limited amount of outside air to circulate between each rafter -- that way you prevent, or at least control, the condensation.

::edit::
Insulations lose virtually all insulating qualities if they don't trap air -- if it's 'smeared' it will get just about as cold as the metal it's adhered to, and the beads of moisture will form on it's surface instead. Couldn't tell you how many times I've had to clear out the fiberglass home owner's tend to pack between windows/doors and framing w/o realizing that it then brings in the cold, and limits air flow so much as to trap the water right there, which is why they quit working ~'-)

 

[chfite]

Before insulating the roof, I would ask myself if condensation is a problem or not.

Chris

 

[Mskayladog]

Well, I had put some foam up high to fill in a hole when we repurposed the lean to, and in the middle of the night I thought now why didn't we have this problem when we had the horse in there and and thought the foam!!! So the next morning I got a ladder and took out the foam and low and behold no more condensation.

The condensation was a problem it was raining in the coop it was so bad.