Insulate roof with foam panels on top instead of blow-in insulation
I have a 1000 sq ft single story house in the SF Bay Area, and I'm paying hundreds of dollars a month to run the central AC and a window unit. And even then on hot days it sometimes gets up to 80ºF inside. Ducts run through the uninsulated "vented" attic (only vents are two holes at the gables).
All the contractors around here react to this by wanting to blow the attic full of fluffy stuff. Aside from the fact that the ducts would still be running through unconditioned space, I dislike the idea. I have this strange long-term attitude toward building that comes from growing up in a 200-year-old house in the Old Country. Basically, I assume I cannot get things perfect all at once and minor changes and repairs are going to happen.
I mean... this one is not 200 years old, but it is from 1950, and it's not exactly top notch construction. I've had an electrician in to replace the old, damaged knob&tube wiring (that's why the old insulation had to come out in the first place, and boy was it disgusting). Then another electrician had to fix a bad connection the first electrician had made. And I pulled wires for the TV, and I'll want new bathroom fans some day, and I've been told the flashing is bad around some roof penetrations. Did I mention the shingles are starting to fail? The idea of doing everything that needs done and being sure nobody needs to go up there for the next 20 years and trusting that no rats will ever make it up there... that all seems far-fetched to me.
How expensive would it be to just insulate the roof deck like we do back in the aforementioned Old Country? Given that I will soon need new shingles anyway, and the roof is a *very* simple shape, could I get the roofer to put foam insulation on top of the current roof deck? Would that be a good alternative? How would I go about finding a contractor that does that sort of thing?
Everyone around here seems to want to just blow the attic full of fluffy stuff and I suspect that their advice is not entirely unconnected to that being the thing they happen to be good at...
Posted Aug 11, 2014 11:50 PM ET
Other Questions in General questions
Can unvented roof assemblies be insulated with fiberglass if I use rigid foam on the exterior of the sheathing?