How to Get the Look of Traditional Trim Using PVC or Boral on Flangeless Windows
I am building a pretty good house (zone 7) right now. Wall system has 2×6 wall with interior service cavity and 4″ of exterior Rockwool (image attached).
My windows will be installed in the 2×6 wall at the sheathing level, along with the WRB. I then need to create extension jambs to extend beyond the 4″ of Rockwool and 3/4″ rainscreen strapping to my cladding.
I am struggling with how to detail the exterior extension jambs with traditional trim using cellular PVC for a more classic look.
Rockwool has a good resource for many installations, including flange and non-flange windows, but they rely on a metal sill and do not go into any detail on how to complete the extension jambs for good drainage. Relevant window pages from the pdf are attached.
Fine Homebuilding covers exactly what I am after with flanged windows here: https://www.finehomebuilding.com/2019/07/09/windows-in-thick-walls, however, they only show the traditional-style trim using flanged windows. Since the flanged windows protrude from the wall, they create a nice box to frame your extension jambs around, then simply fastening the extension jambs to the wall using brackets. This would be done before the exterior Rockwool. The attached image from Fine Homebuilding shows exactly what I am after but instead with a flanged window.
I’d like to use European-style tilt-turns which will not have flanges.
How do I execute traditional looking trim with cellular PVC or Boral Truexterior trim for my extension jambs and trim and create a good seal and drainage?
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