Outie windows with vinyl siding and furring strips
I’ve read every article on this site about rigid foam and outie windows, as well as lots of others and I thought I was all set, but now that I’m almost ready to flash the rough openings, I realize there is a detail that I haven’t seen covered.
I’m in climate zone 5, though only a mile or two from 6.
I have 3 inches of XPS installed over Typar (I’m treating the foam as the WRB, but the inspector wanted to see the wrap under the foam).
I have outie windows with a 1-by picture frame mounted flush with the outside of the rigid foam. Flashed with self-stick Siga products meant for foam, and that passed the backyard tape test reasonably well.
I was planning on putting PT plywood for furring strips under the vinyl siding, but I now realize that my flanged windows need to be farther out to account for the furring strips, so the vinyl can fit inside the flange.
It seems there are a couple options:
1. Build the picture frame flush with the furring strips.
2. Put furring strips around the window (on top the flashing).
3. Skip the furring strips and just mount the vinyl on the form with long nails.
#1 seems the best, though that means I have to take out my picture frames and put in new ones.
#2 seems good, though it isn’t totally intuitive to have the window mounted into the furring strips on top of the flashing, and there might be a problem with that, but incorporating the furring strips into the flashing/WRB seems worse.
#3 sounds even better, since some question the use of vinyl siding with furring anyway.
I realize many of these details have controversial answers, so the only question I’m interested in right now is the picture frame method with furring strips, as every example I’ve seen says to make the picture frame flush with the foam, and maybe that works for other types of cladding, but not vinyl?
Thanks for reading.
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