I am told, by the architect of an upcoming project , that the owners are hoping for the bathroom floor heating system to extend into the shower. The heating system is to be electric and my instinct is to say that it can't be done. Does anybody have any advice ?. Actually , my main concern is not that the system is electric, because I assume it will be under the shower pan, but what shower pan material should be used. This particular installation will be a wheel-chair accessible shower and it would require the membrane to be close to the heating elements.