Exterior Wall Assembly – California 2022 Energy Code
I’m studying adding a second story addition to an existing 1950s single family residence in southern California.
The existing structure is 2×4 framing with a stucco finish. The addition needs to meet current energy codes. Along with the addition I’d like to re-stucco and insulate the existing walls.
With this in mind, I’m looking at R-13 insulation in the 2×4 walls + sheathing + 2″ continuous foam + stucco as the final wall assembly, for both the new and old walls.
Does that sound correct? This seems like thicker foam than I would expect to just meet code. I could go go 2×6 walls at the second floor, but given that the 1st floor is 2×4 walls it makes sense to keep them the same.
Thanks!
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Replies
California is governed by T24 requirements and it is a bit unique from irc. While there are prescriptive options for achieving compliance, you best bet is to hire an energy consultant to run your scenario through the required software (cal cert is one source). In general it should cost around 300-500 for your energy model.
Edit: also changing to 2x6 on second floor is very common in remodel situations for this exact reason