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How to flash and trim exterior of old wood window?

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Jul 12, 2013, 12:50 PM
How to flash and trim exterior of old wood window?

I've removed the exterior wood trim of two double casement windows in order to re-sheath the side of the house. The sills are pretty rotted, so I'll need to, at least, replace the sill nose.

There was aluminum flashing over the windows (which ants had nested behind). Other than that, there was no flashing. Before I replace the trim, would there be any value in adding flashing (I'll definitely put on another head flashing)?
What should I do with the house wrap I'm adding--run it under the wood trim or just up to it? I've seen videos where the house wrap is applied over the head flashing. Would you agree that's the way to go?

This is a pretty plain ranch home, so I don't want to be too ornate, but I'm wondering if anyone has suggestions for head trim that sticks out far enough to provide some protection from water dripping onto the sill.

Thanks in advance for any ideas you can share.
Jul 12, 2013, 04:39 PM
Run the house wrap inside the rough opening. Install the window. The critical flashing point is at the top. If the window has typical brick molding (or for older windows, typical 1x4) go ahead and install that trim with the sides and bottom caulked into the siding. On the top use an aluminum drip edge that can fit up underneath the run of siding above the brick mold with the bottom 90 degree edge of the flashing running over the top of the brick mold (or 1x4) so that the metal flashing expends past the trim.

Doesn't hurt to caulk above the flashing to seal the underside of the siding above.

Jul 12, 2013, 05:11 PM
Thanks Jaybee,

The old window is still installed. I've only removed the trim.
If I'm reading you correctly, you installed the drip edge over the house wrap, but under the cladding (shingles in my case). Is that true? As I mentioned, I've seen videos where they slit the house wrap and and tape the wrap over the drip edge (supposedly re-directing any water away from the sheathing and window.
Jul 13, 2013, 02:04 AM
It defeats the purpose of the house wrap to make a cut in a potential leak area. Let the siding work like it is supposed to - overlap the top of the flashing with the siding, then have the flashing overlap over the top of the top trim. This will direct water down the face of the siding, over the drip edge and out over the trim. If there is any moisture intrusion during this process, (ie from damaged siding, old or missing caulk or by high winds driving rain uphill) then the house wrap will keep that relatively small amount of water away from where it shouldn't be.
So yes, put the drip edge on top of the wrap but under the cladding.