Plywood 'sub-ceiling'?

[MushCreek]

In the place of drywall, that is? I'm doing most of the house in drywall, but I want to use plywood in the kitchen as a substrate. The reason is that I plan to put up a tin ceiling, and prior experience with this stuff is that it can be hard to find something to nail it to. I figured 1/2" plywood will hold the little nails without having to search for a framing member. Is this code? I wonder particularly about fire code.

[akwoodchuck]

Plywood interior finish meets code, but just barely....2006 IRC states, "Wall and ceiling finishes shall have a flame-spread classification of not greater than 200.".....plywood has a flame-spread rating of 150, drywall is 25. It would really suck to get that ceiling done and have an inspector call you out for not having a fire-taped lid behind the ply....

[Don_P]

When in doubt ask the inspector first.  But, I believe the tin is the finish, does it have a rating?

[MushCreek]

I'll call the inspector, but it's hard to get firm answers from them. I would probably coat it with a fire retardant at any rate, although I don't know if that would satisfy them should they balk at the idea of wood.

[astidham]

Im not sure about the code compliance, but I have installed the tin on 1/2 " plywood, it will hold it fine.
I used the tin as my backsplash in the kitchen on my cabin.
we also decided to put in a tin type ceiling in the kitchen over plywood.
after finding what we wanted looks wise, the price (about 13.00 a tile) added up quickley.
we ended up using a foam tile, about 3.00 each, and looks great.
we have pictures of it in oklahoma 20x30 single story

[MushCreek]

An update- the inspector said it would be fine as long as it is sealed. He had to go ask the boss, as no one had ever asked the question before. I'm thinking flexible caulk of some kind. I'll leave 1/8" gaps to allow for movement and to have a place to caulk. I can get fire retardant paint for $60 or so. I'll paint the pieces before I install them.

[MountainDon]

Firestop Caulk should keep them happy

[MushCreek]

That's a good idea. They didn't seem concerned about fire; only that it be at least as strong as drywall, and that air not leak into the attic.