Window condensation issue
I’m in the middle of constructing my home and have discovered a serious condensation / bulk water issue. First some background: We’re in southern Maine. The envelope is a double 2×4 stud wall system 10.5″ thick insulated with Roxul. Exterior air barrier is taped zipwall and interior air barrier is ADA with taped or gasketed seems and joints. No vapor barrier. We put in Intus Eforte UPVC windows.
We’ve made a few errors which are now rearing their ugly head. First, we used 1/2″ plywood shims to install the windows which are the same depth of the window frames and therefore a perfect thermal bridge. These shims (currently exposed on the inside) are getting really wet, seemingly from condensation. The sills are getting really wet too. We just finished drywalling and painting and our HRV isnt installed yet so the humidity in the house is around 65% (I recently fired up a dehumidifier to help). I plan to put a heated fan on these shims to dry them out and tape or caulk them to prevent moist interior air from contacting them. Error number two is Intus windows have weep holes in their frames to let water that gets past their gaskets out. We foolishly blocked these with tape and trim. We had a fair amount of water build up in the frames channels. We’ve since exposed the weep holes and water is now draining. I suspect cold or frozen water sitting in those channels was part of the condensation problem
We seemed to have found the root of our condensation issues or have we? If not, what else am I missing? I attached a photo of one of the particularly bad windows.
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