We are renovating a single story house with 2×4 walls and adding 1.5” foam to the exterior. We are doing “innie” windows. Unfortunately,  contractor has already installed the new windows. To ensure durability, I’m thinking of a picture frame around the windows of 2×4’s (on top of Tyvek) and having the foam butt up to it. Then taping 2×4’s to foam and then flashing from windows out to edge of 2×4’s. Tops of windows are well protected by 24” overhang but would flash top of the picture frame as well. I’m also planning to put 2×4’s on the corners of the house and have foam abut.

Im planning on treated lumber for those 2×4’s. Should I do the same for my furring strips? Seems like consensus is that it’s not necessary.

– Drip edge at bottom of foam
– Glue edges of foam 
– 4.5” headlok screws to fasten foam/strips
– tape seams
– SV5 Coravent at bottom
– coravent at top or vent into soffit???
– treated 2×4’s around windows and on corners (plus furring strips)
– 

Does that all sound okay?

Thank you!