I have three big projects coming up:

  1. Replacing all the windows and a sliding glass door
  2. Adding 2 inches of rigid foam insulation to the exterior and re-stucco-ing
  3. Adding rigid foam insulation against the footings

Since these three projects each interact with elements of the other two, I'm unsure of which one to do first.

I'm worried that if I have a bunch of guys put in new windows first, for example, when I go to increase the effective thickness of the wall by about 2 inches due to the foam insulation, I'll run into problems with window flashing. But if I do the wall project first, how am I going to handle the existing windows? If I add footing insulation first, I need to flash it properly against the old stucco that I'm planning to remove or cover up anyway...

Are these three things that should be done all at the same time?

  • Were you going to use replacement windows or new-work ones?
    – Comintern
    Apr 17, 2014 at 23:02
  • I don't know. Is there an advantage of one versus the other in any of these scenarios?
    – iLikeDirt
    Apr 17, 2014 at 23:55
  • Well, replacement windows can pretty much always go in last because they are basically just sitting inside the existing windows frame. New-work windows would require re-trimming on the inside, but are would make the flashing better on the outside because you wouldn't be going over the existing flashing (or fixing it if it isn't already there).
    – Comintern
    Apr 18, 2014 at 0:38
  • Are new construction windows cheaper? I'd probably prefer to go that path because I'd be redoing the siding, and there currently IS no interior trim! :)
    – iLikeDirt
    Apr 18, 2014 at 0:43
  • Prices aren't that much different around here, maybe a bit cheaper for the new construction ones, but you get much better quality for what you pay for them.
    – Comintern
    Apr 18, 2014 at 0:57

1 Answer 1


I think I've answered my own question:

I'm going to do the footing insulation first. This will increase the effective thickness of the footings and result in a metal flashing plate over the footing foam at the bottom of the existing walls (for drainage and termite control/visibility).

I can use that for the wall project by resting the wall's new foam insulation on top of it. I haven't decided whether to screw the foam directly over the stucco or remove it first (see Adding insulation to exterior wall; remove stucco cladding, or add on top of it?), but regardless,during that time I'll remove the windows, build plywood bucks to put in new ones over foam and flush with the new stucco cladding, and flash them like so:


enter image description here

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