I want to do a radiant floor in my family room. I only have one inch between the plywood subfloor and the frame for the sliding glass door. Should I apply gypcrete to only one inch depth, or can I do gypcrete at one and one-half inches and "feather" it closer to the patio door? I want to install ceramic tile. Gypcrete looks pretty liquid so is installing gypcrete possible, or do I look at other alternatives like light concrete?