Exterior window jamb treatment for rigid foam?
I am stumped. We are using 2-3″ of GPS exterior insulation on our addition/renovation.
So if we put the WRB on sheathing below the GPS, and likewise install the windows with their flanges at the WRB, what exterior jamb/trim should be used if we end up using 3″ of GPS?
Layers atop the WRB/windows would be: 2-3″ GPS, 1/2″ furring strips, and a vertical steel siding which is 9/16″ thick.
The window manufacturer we are considering (Duxton) has a 3.5″ exterior trim. So if we do 2″ GPS, we’re at 3-1/16″ altogether with the furring strips and siding, and if we do 3″ GPS, so the 3.5″ trim should be OK, but if we’re at 4-1/16″ altogether. What do people do in this case? Build out the window frame to bring the flange out an extra inch? I know the thermal buck is supposed to be a solution to this, too, but I don’t yet understand how that would interact with the windows.
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