IRC 2009 R807.1 in low infiltration construction
Citing IRC 2009 R807.1 (“Attic Access”) [1] my city rejected my 1010 project [2] plan which, in an effort to limit infiltration below 0.6ACH@50P, does not include an access point into the R-91 attic. The slope of the roof is such that, without significant design changes IRC 2009 R807.1 is in effect.
Someone else has been here, I’m sure…got any insights to share?
The idea of including an attic access to comply with R807.1, only to seal it up to meet 0.6ACH@50P is just plain silly; but dropping the pitch of the roof to avoid R807.1 even more difficult.
Any recommendations you’re willing to share are greatly appreciated.
Cheers,
Jan
[1] http://publicecodes.cyberregs.com/icod/irc/2009/icod_irc_2009_8_sec007.htm
[2] http://1010-design.blogspot.com/
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Replies
If your roof has gables perhaps you can have a gable end access, possibly a cheap window. Another possibility, which I'm planning on using is access through the ceiling of a covered porch. both get the access port outside of the air barrier.
Hi Jerry @ 1:
At least in little Salt Lake City, "an outside location only accessible by a ladder is not an [readily] accessible location" - but perhaps this just an unusually narrow interpretation of R807.1, or is this a common interpretation of this code?
Jan:
Might want to ask this question over at the ICC's forum, if you haven't already.
I have seen pull-down stairs installed on porches. That would certainly seem to be readily accessible, especially compared to some of the tiny attic hatches installed in closets.
Nothing in the code requires that it be a hinged door/hatch, just a framed access point.
I've seen several houses where the attic "access" was a framed section in the ceiling that is clearly a hatch, but 5/8" gypsum lightly mudded-in (but air-tight) at the edges, easily broken out with a fist-punch should access ever be needed for inspection/maintenance/firefighting. If you're careful about how you break it out it's pretty close to air-tight when you set it back down too.
Insulating that breakaway gypsum door to R91 probably isn't in the cards, but EPS/iso is pretty light stuff, and making it R50 with rigid foam wouldn't be outrageous.
The drywaller usually cuts a panel for the access hole and sets it on top of jamb returns that run a couple of inches up above the ceiling plane. Then it gets sprayed with texture, sprayed with paint, and it's nearly airtight. If you have some foresight and glue a healthy thickness of foam on top of it, it will not constitute a weak point in your envelope. I glue 8" of polyiso on top of them and then maneuver them into place when the glue has set up.