I have a lean-to hobby GH, attached to heated garage with a door. I also have a natural gas heater in my GH that DH installed for me. I do use bubble wrap on the upper half of the GH and rigid styrofoam panels on the bottom half. The GH frame is metal and has double wall poly panels. I use blue painters tape to tape the bubble wrap (a double thickness) to the frame. For the slanted ceiling, I'm able to thread the bubble wrap through the cross supports and then tape to the frame. Sometimes the tape gets too wet from the condensation inside the GH and fails but not often.
