I have a wall profile that looks similar to this:

Wall profile

but where the flashing is shown, the horizontal distance is much larger. The structural engineer I contacted said that my house should have been given a brick facade, so the horizontal section there is wide enough for the sheathing and a course of brick.

Long story short, I've got some pretty dramatic water damage from some incorrectly installed siding/flashing, and I'd like to not make the same mistakes the previous owners made.

I found a video on getting the flashing bent to the correct profile for very long pieces, but I still wouldn't be able to get the flashing to surround the house in one continuous piece of metal. Somewhere, it has to overlap. How do you seal a basically horizontally-mounted piece of flashing? Should I look at brazing or welding (drawings call for aluminum flashing), or is there something else?

I think I would prefer to not rely on caulk, but of course if that's the only answer then I guess it's the only answer.

1 Answer 1


The Z flashing is there to prevent water from creating water damage as you have noticed. The flashing is usually overlapped and that is sufficient unless in a windy area then a very small bead of calk between the overlapped flashing can be used but is not needed when properly installed. When I used to build homes on the west coast we would lap the flashing with the west most flashing on top so that driving rain would not be pushed under the overlap even if lapped in the opposite the metal to metal contact should be enough with good siding. There were some siding products "LP composite" that even with proper flashing failed (big class action lawsuits). I don't think brazing will do much more than proper lapping.

  • Would capillary action not wick water/moisture up between the lapped flashing?
    – Chuck
    Commented Feb 15, 2017 at 19:11
  • If it did the same or worse would be true of step flashing on roofing when needed and I have never had an issue with step flashing wicking.
    – Ed Beal
    Commented Feb 15, 2017 at 20:21
  • Fair enough. Any guidelines on how far the sections should overlap? 2 inches? 2 feet? Thanks for your help!
    – Chuck
    Commented Feb 15, 2017 at 20:22
  • A minimum of 2 inches and if you have high wind 4 would be better some code may require 4 but it has been a few years and I am not sure of the minimum requirement.
    – Ed Beal
    Commented Feb 15, 2017 at 20:26

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