Replies

1. Expert Member
   Dana Dorsett | Jan 28, 2014 03:52pm | #1

   It helps if you clue us in to which state, eh? (The stretch code in GA wouldn't meet code-min in MN.)

   In most states with stretch codes the "stretch" is only to about IRC 2012 spec on R-value for the climate zone:

   http://publicecodes.cyberregs.com/icod/irc/2012/icod_irc_2012_11_sec002.htm

   https://www.greenbuildingadvisor.com/sites/default/files/images/H-T%20Zones%20with%20Cities%20ABC+.jpg

   Air tightness for IRC 2012 is 3 air exchanges per hour @ 50 pascals, blower door tested, but that won't apply to a remodel unless it's a truly extensive rehab (like a full-gut). Caulking the sheathing to the studs, and between doubled-up stud plates, between bottom plates & subfloor, subfloor to band joist, band joists to foundation sills, and foam sealing foundation sills to the foundation-insulation foam, as well as foam sealing all electrical penetrations of the sheathing & studs (including the lateral electric runs at each stud) go a long way toward meeting air tightness goals. Backer-rod + low-expansion foam air-sealing of the windows counts too. Don't skip the interior gypsum or other air barrier behind bathtubs etc- a common but horrific thermal bypass path.

   Even at the stretch-R there are different ways to get there, with different costs and consquences. An R20 2x6 wall is the code-equivalent of R13 2x4 w/R5 of exterior continuous insulation (usually foam), but with the former the sheathing runs cold in winter and may need an interior vapor barrier, which would make the assembly less moisture resilient. An R13 + 5 wall can skip the interior vapor barrier in climate zones 5 or lower, which keeps the sheathing warmer (=drier) in winter, and has VERY good drying capacity toward the interior, making it a superior way to go. There are advantages to going even deeper on the exterior insulation, but if you're shooting for the absolute minimum amount of exterior foam that's both moisture resilient by allowing you to skip the vapor barrier, follow these code-prescribed minimum values:

   http://publicecodes.cyberregs.com/icod/irc/2012/icod_irc_2012_7_sec002_par025.htm

2. 
   user-1072251 | Jan 29, 2014 10:37pm | #2

   start by reading web sites like this thoroughly; there is a lot to learn. If there is a building conference in your area, go. These are better buildings by a long shot, compared to code minimum houses.

3. 
   heidner | Jan 30, 2014 12:53am | #3

   Building America (DOE) website has some of the building science work that has been collected funded over the years. Years of research and experience intended to help all... some of it done by contributors/authors of this website..

   DOE also has their "Challenge Home" program on going for new homes. Some of their basic goals would work well for remodeling...

4. 
   jeffsinmass | Jan 30, 2014 05:15pm | #4

   thanks for the input.
   the state is Massachusetts
   I'm more concerned about the new iecc 2012 that's becoming effective in July, in my state.

   trying to figure what tips & tricks other people have come up with or learned