Metal roof insulation?

Can you put insulation (thinking closed cell polyurethane,or iso) directly under a metal roof? If so does it get fastened down with just the fasteners of the roof? How thick can it be (thinging about the edges of the roof being raised)

[Leinie]

I've never seen that done. That doesn't mean it can't be. I've only seen insulation stuffed between the structural members , or sprayed on the bottom after the metal is on.

[v-bay gord]

I think it would be best to put down the rigid insulation and then strap over it with 1x 4's and then screw the roof to the strapping.

[northernbite]

Remember open space between or in my mind air is your friend. I'm editing this because in large dairy barns there is a rolled product they put down and the metal over it.

Paul

[Phil T]

The steel buildings at my old industrial job had thick plastic bagged fiberglass insulation that was held in place with wire chicken fencing strung across the roof beams. A simple but effective method. The wire fencing on the wall insulation resembled yard fencing.

[JJ Scully]

Originally Posted by Cliff M

Can you put insulation (thinking closed cell polyurethane,or iso) directly under a metal roof? If so does it get fastened down with just the fasteners of the roof? How thick can it be (thinging about the edges of the roof being raised)

First yes it can be put under a metal roof. As for fastening it is usually fastened enough to hold it down until the steel is screwed down. As for how much I would ask what are you looking to do with this insulation? Will there be uninsulated attic space between your existing insulation and this new insulation? There are trims available to cover the height difference if you were to add a few inches of insulation.

[CKM]

not sure what insulation you are referring to. A lot of people are now having foam sprayed to the underside of their steel roofs. walls to for that matter. You can also use sheet foam under the steal. that's the way it always used to be but that is slowly disappearing and being replaced with spray foam.

OK, I'm sorry my fault, ..I didn't make it clear,..I have a house that needs a new roof, Thinking about using a flat black or verdigris green. I want to put it over the old asphalt shingles (not too bad shape not curling) I was told this was possible saving tear off. For energy saving esp heat on this south facing side , I thought of putting down 1-2 inches of the real closed cell Styrofoam or equivalent of iso board. I didn't know if this was done before asking a contractor. Wondered if anyone has done this?

[CKM]

first of all you attic is probably vented. or it darn well better be. so installing the foam will do nothing to help your heat bill. and as a guy that built homes for fifteen plus years, the last thing you want to do is install that steel over those shingles. that would rank up there with one of the dumbest things a person could do. I don't think your insurance company would touch that with a ten foot pole.

[Justfishing]

Originally Posted by Cliff M

OK, I'm sorry my fault, ..I didn't make it clear,..I have a house that needs a new roof, Thinking about using a flat black or verdigris green. I want to put it over the old asphalt shingles (not too bad shape not curling) I was told this was possible saving tear off. For energy saving esp heat on this south facing side , I thought of putting down 1-2 inches of the real closed cell Styrofoam or equivalent of iso board. I didn't know if this was done before asking a contractor. Wondered if anyone has done this?

most recommend taking up shingles. Then put down rigid insulation. Look for reclaimed insulation it is much cheaper. You need to put done enough rigid so that the osb is not a condensing surface.

I would go to greenbuildingadvisor.com to get help.