Actually THAT thought had crossed my mind before. I think you're suggesting heating up the base instead of putting a heater into the water? If you come across any plans I'd be very interested!! DH and I take our time with our animal building projects so we don't have anybody hurt with the materials. We have a laundry list of 2012 projects to do. #1 is to take an outbuilding that's falling apart at the base and rebuild it for my chicken's coop. Here is the 7 x 8 (approximately) building: (NOT the best shot, but you get the picture bc the house is purple!) The roof is in great shape, but we're already stripped the windows out. Once we remove the roof we're going to take it apart, catalog the pieces (take pictures, print and mark them) then rebuild or replace damaged pieces. We have REALLY learned a lot from the projects we're done in the last few years. I've learned to start collecting materials early for my projects. I'm redoing 4 raised garden beds and I don't want to be spending my free time driving around getting wood when I wake up to a warm, dry day to build.
I've also learned the my DH has some excellent ideas, despite the fact that he is NOT a professional builder.