I'm wrapping a block wall house with rigid foam insulation. I plan on liquid nailing it directly to the exterior block wall of the house. I plan on attaching furring strips with tapcons on top of the insulation through to the block wall. I'm finishing with Hardie plank siding. If any of that sounds wrong let me know, but my main question is window installation. I'm going to build out plywood boxes for the windows, but should the flange on the window attach at the level of the foam board or the furring strip? Is the insulation strong enough to attach the window via the flange through the insulation to the block wall with tapcons? Or should I find a way to attach the windows with like a metal strap into the wood framed jamb?

  • This is mainly going to depend on the depth of the window flange vs. the depth of the insulation. In general, attaching the window directly to the exterior sheathing (or in you case it sounds like "substrate") is best. The exception would be if the trim leaves a gap around the flange due to the thickness of the insulation.
    – Comintern
    Oct 5, 2014 at 23:55


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