I’m bidding on a window replacement job on an older house. The wall assembly consists of ~1 inch thick stucco applied directly to a lath over the the 2×4 studs (no sheathing, not even the old style 1x planks. There is 1/2″ drywall inside. So the entire wall thickness is about 5″ (4″ for the studs and drywall alone, as opposed to the standard 4 9/16″ for a 2×4 wall). The windows being installed are standard 4 9/16″ units that are designed for the fins to attach to 1/2″ sheathing so the interior of the window frame sits flush with the drywall. We are using Sierra Pacific windows with an integral brick/stucco mold, so there is a groove that will help secure the stucco. The existing windows are aluminum casements.
The way I see it, I have two options.
1. Install the window fins against the studs (with proper flashing) and apply a backband to the interior casing (window frame will protrude 1/2″ beyond the drywall.
2. Install 1/2″ furring on the exterior perimeter of the window opening, flash, and mount the windows. The interior frame will be flush with the drywall, but the stucco would be only 1/2″ thick (to remain in plane with the existing) around the window fins.
Thanks in advance.