Insulating a scissor truss
When insulating an unvented scissor truss roof with loose cellulose, ~24″ heel height and ~ r-30 spray foam against the underside of the roof decking, can I leave an increasing airspace as I work my way up to the peak? In other words, I want a consistent thickness of cellulose (~18″) starting from the raised heel up to the ridge. Can the remaining space between the cellulose and spray foam be a air space or am I risking condensation somewhere in the sandwich? This is assuming air barriers at the roof decking level and bottom chord. BTW: Zone 7-8. Thanks.