Find a Contractor

Roof insulation

Back to I Have An Existing Metal Roof and Have A Question
Back to Forum
Guest User
3/23/2015
I have an a frame cabin with 2 inch tongue and groove decking with metal on top. There is no way to insulate the inside. I want to foam the outside. I can't get consistent answers on how to do it. I would like to remove the metal, put something over the wood, build a 2x4 frame, foam the cavity with closed cell foam, put osb decking on the frame work and put the metal back on. What kind of under lament should I use? Do I need any venting? I need some suggestions,
Todd Miller
Isaiah Industries, Inc.
3/23/2015
It sounds like what you're building will not require venting. That said, venting and a thermal break in the system would only be helpful, not harmful. I would suggest a layer of quality synthetic underlayment, or whatever the roofing manufacturer requires.
Guest User
3/23/2015
So if I remove the existing roof, put an under lament, shark skin or similar. Then build the frame work with 2x4, foam the cavity full (3 1/2) inches, with closed cell. Put osb decking felt paper or ?, then put the metal back. Would that work?
Todd Miller
Isaiah Industries, Inc.
3/23/2015
The underlayment I was referring to would be on top of the decking, directly beneath the roofing. What you are referring to would be more of a vapor barrier. Installing a vapor barrier would not be a bad idea. I would probably do an impermeable vapor barrier for that rather than a roofing underlayment through.
Eric Novotny
An informed customer is the Best Customer!
3/23/2015
Why not just use rigid foam over the roof sheathing? This type of system is fine. You can air seal the T&G boards by just putting peal and stick membrane over it.

If you would like to reply to this thread, please log in. If you do not have an Ask the Experts forum user account, create one here.

Find a Contractor

Get Started Today

Take the first step to increasing the value of your home with a great looking, durable, fire resistant and energy efficient metal roof. Browse our list of qualified MRA Member Roofing Contractors in your area for a free consultation and estimate.

Search Now