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Community and Q&A

Window head flashing is at the top of the window or top of the window?

Ryan_SLC | Posted in General Questions on

Hello,

I can’t quite find what exactly is head flashing.

Hammer and Hand and Fine Home have it at the top of the trim ABOVE the window:

3.1 New Window Installation

Adding Head Flashing

Fine home also uses a nailer to attach a window…so I almost don’t even want to consider what they post:

Installing and Flashing Windows Correctly

Marvin windows as it directly on the window, along with Anderson:
https://www.marvin.com/blog/a-guide-to-window-rigid-head-flashing

So is the answer to head flash on both is the most robust? It doesn’t seem like pros agree all horizontal seam needs a top and bottom drip? It seems to this rookie, they do not serve equal protection. Trim doesn’t typically get a required yes answer to a top drip edge vs a bottom for example…so

What is old ideas on the internet vs current best practice? Is it drip cap on window and z on the trim? Best?

Thanks!

 

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Replies

  1. Malcolm_Taylor | | #1

    Ryan_SLC,

    It depends on whether the trim is mounted on top of the cladding or in the same plane, and whether there is a rain-screen.

    - If the trim is mounted on the cladding, the head-flashing goes over the window.
    - If the trim is mounted directly to the sheathing, the flashing goes over the trim.
    - If there is continuous rain-screen strapping, and the trim is mounted directly to it, then you need two head-flashings. The one over the trim is mounted to the strapping, the one over the window extends back under the WRB.
    - If the rain-screen strapping stops above the trim, you only need one over the trim, which extends back behind the WRB.

  2. Ryan_SLC | | #2

    If I can abuse your expertise some more? I'm going to install the Mortairvent 3d mesh. My trim is PVC.

    I am unclear if it benefits for me to put the trim on top of the 3d mesh vs just nailing the trim directly to the sheating/on top of the house wrap.

    Same applies to above given the 3d mesh wrap instead of the true rain-screen?

    Thank you! Thank you!

    1. Malcolm_Taylor | | #3

      Ryan_SLC,

      I'd be tempted to run the mesh behind the PVC trim to give it a bit of drying capacity. How about this variant of the last option I mentioned: Use a separate piece of mesh and WRB under the head-trim. That way you can use just one head-flashing over the trim, and still lap the WRB and mesh over the back leg.

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