Changing Roof Code Requirements (suggestion)
This isn’t a discussion about shingles, vs. tiles vs. metal. Its about the design style, the aesthetics, and the creation of an open attic space as a condition of allowed conditions. Considering the cost differences of ceiling the attic, bringing it into the conditioned envelope, and moving the insulation efforts from the top floor’s ceiling joist cavities to the roof itself seems like a wise consideration. While I understand that not all roof ‘designs’ lend themselves to using something like SIP panels, quite a bit of tract building seems to be accommodating (in terms of design). The days of municipalities affording consumers to fight the +140º summer attic temps pushing into the conditioned space, which then requires additional cooling capacity needs to change. I have often thought about how interesting it would be to rip the roof off of my house and replace the rafter framing with SIP panels, ceiling the attic in turn, and bringing the attic into the overall conditioned envelope. Am I nuts?
Replies
Cheaper still is just bring all that HVAC equipment down into the conditioned living space. No reason to go into a 140* attic space then, or rebuild the roof.
Nuke:
Conditioned attics are nothing new, and most model codes do allow them. As far as them being required, that isn't gonna happen during my building career. Maybe not in my lifetime. Although it is a viable construction method, it has been one of the slower new construction methods to catch on and is fairly uncommon. I think it is because builder types (like me) are afraid of what problems might be produced. Total roof failures caused by lack of venting and moisture build up have occurred. The roof sheathing turns to mush. That may have been isolated to fiberglass insulated roofs - not sure. One was pictured here fairly recently.
Re SIPS - yes you are crazy. :-) If you were building a new house it would be more feasible. Also pictured here some time ago was a SIP roof where the seams between the SIPS were telegraphing through the roof covering (shingles). I don't know what the cause or resolution was, and am not saying that kind of SIP failure is at all common, I'm just saying that this whole conditioned attic thing isn't necessarily trouble free.
If you really wanted to go to a conditioned attic the best way might be to have spray foam installed. Wild Guess - $5k.