5

How should I flash this tricky corner:

enter image description here

This is at the junction of a 2 story section and 1 story lower flat roof, done in foam. The flashing was installed about 20 years ago, the wall below rotted and became a termite nest for various reasons, perhaps including the flashing.

This is the twin of the flashing at the opposite corner. There's no evidence of rot there, but then again, the first corner's problems were not in evidence prior to removal of stucco:

Stucco weep screed transition at corner over roof

Further back showing the junction of the 1 story addition. The major water originated in a window just above here, now fixed:

enter image description here

The water encouraged termites, who had probably decades to chew at the corner. This is what it looked just after removing the stucco. As is typical, none of this showed from the outside, the stucco shell showed no unusual cracks or problems:

termites in old growth doug fir

Flashing just prior to first removal of stucco. It was removed because of the crack you see:

enter image description here

And an overview of the good corner, twin of the bad corner:

Mediterranean House Water Problems at Parapet Joints

Bryce
  • 11,057
  • 18
  • 77
  • 120

2 Answers2

3

Cement is porous, not waterproof, it acts like a sponge and will hold water. It also allows water vapor to pass through so condensation does not build up in walls. Tarpaper also allows water vapor to pass as well but not water itself. Tyvek has the same properties too. The point I am making here is the tarpaper is your waterproofing layer and the stucco or any other masonry surface like brick, only provides protection for the tarpaper. If the tarpaper is not layered right or flashing is not installed properly you will get what you have now. The flashing prevents water from getting behind changes in plane, like a roof (sorry for the obvious). The mention about the paper going up to the top of the new extended flashing, is to treat the tarpaper install like there is no flashing there at all so the watershed properties of the tarpaper stay intact where the flashing and its "turnout" end. enter image description here

enter image description here

enter image description here

Jack
  • 38,117
  • 2
  • 30
  • 66
0

Just looking at the picture with the R13 in it. Just get a 6"x6" right angle flashing and lay it on the vertical corner above you other flashing. You will just slide it down over the other flashing but you will have to cut in a birds mouth right about at the R13 letters there. (you can actually just make a straight cut) It will give you that bow you need to prop over the other flashing. You can put a small piece of the 6x6 flashing under the bird mouth to cover wood that may be visible now. Also use tin snips to get that nice transition from the new to the old. Trial and error works well. If you get the new and old to line up nicely you can add a rivet right at the corner. Use flashing sealer as needed.

vin944
  • 254
  • 1
  • 5