The rubber IS glued to the roof. The entire roof is coated in adhesive and the rubber put down on top of the glue and smoothed with a soft push broom or a wide paint roller with a new pad.
The adhesive is water based and has to have wood for the water to soak off into to cure. If you apply the adhesive over old adhesive the glue will never cure, as the old adhesive seals the wood. Some people skin over the old roof wood with thin luan plywood glued with construction adhesive and short nails, but this leaves reused corner trim not fitting and adds significant weight. I opted to remove all roof sheathing and replace it. We lay out the rubber, got it all positioned, folded back the front half and rolled the adhesive on, and very carefully pulled the front half over the adhesive, smoothed it down with paint rollers, then folded the back half forward and did the same thing over again.
The roof came out very nice.
The interior ceiling is attached to the roof trusses and framework, then it is flipped over and installed on top of the walls, sandwiching the ceiling luan plywood in place making it impossible to replace.
Charles
