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Community and Q&A

Flashing a door opening – sill in particular

user-2069108 | Posted in Green Building Techniques on

I have seen specially fabricated metal sill pans and membrane on this web site. Thermatru sells a formed plastic sill pan, and there are the much more robust plastic pans from Sure Sill.
Is a membrane sill pan durable enough for a door? How about the plastic? Sure Sill pans appear to cut significantly into the RO size.
Any suggestions or comments would be welcome.

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  1. GBA Editor
    Martin Holladay | | #1

    Careful workmanship is probably more important than the type of product you use. Here is my advice:

    1. Every exterior door should be protected on the exterior by a roof that has eaves that are no more than a couple of feet higher than the door head. (In other words, the overhang on a roof that protects the second floor of the house isn't good enough to protect a first-floor exterior door.)

    2. Every door rough opening needs a sill pan. If the house has a slab-on-grade foundation, it's best to create a recess in the concrete at the door location.

    3. The sill pan flashing should either be sloped to the exterior or should include an interior dam.

    4. The rough opening needs jamb flashing that directs water to the sill pan flashing.

  2. user-2069108 | | #2

    Good advise, Martin. I will have to get a small roof over my north and south doors - maybe a small shed roof that I can cantilever out from the wall. It will have to be bolted/screwed through 6" of ISO foam.
    Otherwise, I plan to flash the opening thoroughly and effectively.

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