Foil face foamboard under ceiling drywall

[zurud]

What you guys thought of using aluminium face foambard under drywall ceiling to keep heat in winter . I notice if you wrap hot food in aluminium foil it stays hot for a long time. However I don't know about the firecode of it.

 

[tomstin]

Foam is a disaster if it catches fire, lots of fumes that will kill you quick. I understand that most fire codes require any foam products be covered with a fire resistant coating, most usually drywall. However, aluminum faced foam board would probably be a very good insulator.

 

[jimp]

If you are talking about a Thermaxx type form board.

THERMAX™ Sheathing is a non-structural, rigid board insulation consisting of a glass-fiber-reinforced polyisocyanurate foam core laminated between 1.0 mil smooth, reflective aluminum foil facers on both sides. The reinforcement, along with chemical modifications, contributes to fire resistance and dimensional stability. THERMAX™ Sheathing can be installed exposed to the interior without a thermal barrier and is especially appropriate for hourly rated assemblies.

Kind of expensive, but the best R value of all the foams. I would just insulate above the dry wall with fiber or paper( if you have access).

 

[richtersrodz]

I don't have foil foam board, but I have foil sided OSB on my roof. It's a killer on the tv antenna in the attic, and gets us horrible cell phone reception inside the house. We usually have to go and sit out on the back porch to talk on the phone.

 

[Falcon67]

I used ThermoShield OSB on the shop roof and end gables. No problem with cell phone use or wireless internet. And, it works. The Thermo stuff - also the foam - is designed to reflect heat back away from the space the reflective side is facing, not the other way around. The best way to trap heat in the lower space is to make sure the ceiling is as air tight as it can be and pile the insulation on top of that.