On Mon, 12 Nov 2012 16:55:05 -0500, Keith Nuttle
wrote:

We are putting a 41" X 33" mirror in the tv hole above our fire place.
The Mirror is 1/4" thick. The TV hole is standard framing 2x4 with
header. The mirror would fit into the hole in the existing framing with
the trim that was applied for the TV hole.

The plan was to put a 1/2 inch sheet of plywood as a backer board for
the mirror. The mirror and the backer board would be held against 1X2
frame attached to the trim of the existing TV hole.

Today I went to get the wood to cut the 41X33 backer board from.

I realized that even 3/4 plywood will warp not a good thing if the
mirror is masticed to it.

It shouldn't warp in the dry inside air, and it shouldn't get hot if
you use your fireplace correctly (flue open). DAMHIKT


What would you recomend for a backer board?

I have talked to several people with ideas all over the board. from
sheet rock to no backer.

MDF, aka Termite Barf. It's more stable. DO seal all faces and edges,
though. Are you going to make a hidden compartment, too?

--
While we have the gift of life, it seems to me that only tragedy
is to allow part of us to die - whether it is our spirit, our
creativity, or our glorious uniqueness.
-- Gilda Radner