Used two pieces of 1/2in foam insulation panels cut to fit between each roof/ceiling joist, with knife slits cut (like kerfs) so it would "bend" easier. Lined the inside piece with a cut-up old tan bedsheet so blue insulation wouldn't be seen behind the bamboo slats of the ceiling. The binder clips on the roof joists are simply keeping the insulation bats from popping out until the roof is attached.