another flexwatt question

[bidden]

I'm planning on building racking system out of melamine(sp?) and having ceramic tile for the floor of the enclosures... Can I attach the tape directly onto the underside of the tile and then leave a small space between the tile and wood shelf so the tape isn't directly on the wood?? or can I just sandwitch the tape between tile and wood without leaving small gap??

my gut instinct tells me that heat tape directly on wood shelving is bad, but I might be wrong.....