[encantotom]

when i did some on my 90 i only needed to do the top layer. an it didnt really matter where you cut it out because you could just make new furring strips along the edge of where you cut it.

it had a 2" floor. started with 1/2" plywood base, then furring strips that were 1" high made of 2 pieces of 1/2" plywood and then a 1/2" plywood on top. in the spaces between the furring strips was 1" foam insulation.

tom