Joe wrote:

I figure it will have two opening hatches each 1' X 3'. I will either
go with 3- 1'X1' panes, or a single 1'X3'. I think the 3 panes would
look better but would be more prone for leaks.

The required thickness for given loading depends on the type of glass - some
types of treatment can make glass very flexible. FWIW, the Houdini hatches
(about 20" square) have 1/4" toughened glass with some aluminium bars over
the top. At a guess, I'd imagine that 1/2" would be the absolute thickest
you'd require, probably less for the right treatment.


--
Wally
www.artbywally.com
www.wally.myby.co.uk