Window detail question: flashing over bottom nail fin?
I just finished installing some new windows and am having second thoughts about one flashing detail.
Particulars: Austin, TX, Zone 2, South East facing wall. Concrete block construction, rough openings brought to size with treated lumber bucks. Windows are Milgard fiberglass, with integral wood inside. Wall has 2 foot eave (but up quite high since it’s a gable end). Eventually we’re going to finish out the wall with either foam or mineral wool, rain screen and siding.
We ran beam of caulk between bucks and concrete before fastening them. We then flashed the bottom buck before install using Protecto Wrap BT-25XL Butyl Peel/ Stick , paying attention to the corners as shown in GBA window flashing vids. We installed the windows using a continuous bead of caulk as in the manufacturer’s instructions, we didn’t need many shims thanks and screwed the nail fins into the wood (three sides, concrete one vertical side due to RO constrains).
Once in I applied more of the Protecto Wrap right around the windows, starting with the bottom then the sides and finally the top, so the lapping is right.
Throwing the Protecto wrap away I noticed that they show the bottom fin not flashed on the outside (only under the fin). At first I thought this might be for drying or drainage if any water were to get inside and was about to cut out and remove the bottom outer flashing.
But then I realized there’s caulk all around under the nail fin anyway and so it really can’t matter. Thus I left the flashing (but will cover it with painted wood trim in the next week or so, claims 120 days in sun ok).
So, the question is: right thing to leave it (realizing it’s unnecessary but not harmful) or should I remove it? Does it make sense to make any provision for drying from between window and buck (window has weep holes at bottom, those are totally uncovered), especially when caulk is applied under nailing fin?
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