I'm making a "strong" but cosmetically acceptable (I hope) external door
out
of a fire door blank and a sheet of mahogany faced 18mm ply.

I intend to cut out 4 rectangular holes in the ply so when it goes onto
the
firedoor blank, the whole thing looks like a decent external panelled door
once I put some mouldings round the inside edges / lips of the "panels"
and
surround the outside edges of the door with 1/2" thick mahogany
(framing/sealing it).

It's a strength/cost/cosmetic compromise! I got all of the wood for £60.

Obviously I'll seal/protect it all heavily and use good woodglue /clamps
to
mate the ply & doorblank surfaces.

My main question is, in addition to the glue, will I also have to pin or
screw the ply to the door to prevent shrinkage/warping at different rates?

I'm happy to screw it, but how will I best cover the screw holes up - will
plugs be obvious? I intend to stain / varnish.


Meant to put on original post; my "fire door" says "Lightweight Firecheck
Doorblanks" on it.

Thanks
Paul