I'm replacing an older wall oven with a new one and the cabinet depth (front to back) is only 23" while the specs call for 23.5" minimum. I don't have the new oven unit yet to actually see how well it fits but am concerned that my cabinet space is 1/2" too shallow. It looks like I have enough room between the back of the cabinet and the dry wall behind it to just cut out the back of the cabinet, but am concerned about whether that would be acceptable, or if I'd need to install some sort of fire resistant material on the dry wall also to be able to do this. I can't find anything on this in the local code book. Anybody have any experience with this issue? Thanks for any help.