I am building an addition in San Carlos, CA (SF Bay peninsula). The room is about 19′ x19′, 8′ tall ceiling, and has an 8′ x13′ endless pool. (The pool will be covered when not in use.) The roof/ceiling is unvented, low-slope with liquid roofing (Pacific Polymers). The trusses are about 12″ to 13″ tall at the walls and roughly 14″ to 16″ at the ridge. I would like to use open-cell icynene spayed thick enough to get R-30. (If the roof leaks, I would like it to drip through the insulation). In an unvented roof, does the spray foam need to fill the cavity completely. If not, what are my vapor barrier options/requirements. The ceiling will be painted drywall.