How to frame in a window with continuous insulation
I am building a one level SFR with 2×6 walls w ZIP sheathing, using Senergy Platinum CI stucco system on the exterior and high efficiency WS Contemporary Series windows with a flush frame. It looks like the exterior wall system will be roughly 8-3/8″ thick from drywall to stucco. We’d like to recess the windows as much as possible, perhaps 4″ on the exterior. The windows are 3-1/16″ jambs without a nailing flange, which totals about 4.5″ for the window frame. The question is: With a narrow window face frame, which is roughly 1/2″ wide, what is the best way to return the insulation board & stucco to the window without running it into the window frame that will assure a tight seal and be weatherproof? Will the windows be stable using the metal window clips to install them? Should I skip the recess and make them flush with the exterior? Is there a better way?
I have attached a drawing to better paint the picture of my dilemma. I cannot seem to find any references on the Senergy site and am awaiting technical response. However, I am not sure they will give me best practices. Any suggestions or feedback is welcome.
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Replies
Tracy,
Q. "What is the best way to return the insulation board & stucco to the window without running it into the window frame that will assure a tight seal and be weatherproof?"
A. There are lots of ways to do this. You have chosen to install your windows as "innies," which is fine. If you change your mind and decide to install them as "outies," that's fine too. It's your choice.
If you install your windows as innies, you need exterior jamb extensions and an exterior sill extension. Whether or not these extensions need to be waterproof depend, in part, on the location of your water-resistive barrier (WRB).
If your window rough openings are carefully flashed to the WRB, and you have a WRB between your exterior rigid foam and your wall sheathing, then your exterior jamb extensions may not have to be perfectly watertight. But in all cases, your sill extensions need to be perfectly watertight.
It looks like you want to use stucco for your exterior jamb extensions. That will work, as long as the water management details are thought through.
For more information on this issue, see Installing Windows In a Foam-Sheathed Wall.
Q. "Will the windows be stable using the metal window clips to install them?"
A. Yes.
Q. "Should I skip the recess and make them flush with the exterior?"
A. That's up to you. Many builders feel that it's easier to flash outie windows than it is to flash innie windows. But innie windows are better protected from the weather, more likely to be shaded, and are likely to perform slightly better from a thermal perspective than outie windows.