what would be the draw backs to using one full piece of 12" flashing folded
to 6" instead of seperate step flashing when installing new roofing shingles
on an addition where it butts up against an existing vertical wall of the
house? The flashing will be behind siding.
It is a bit like deciding whether to lace a valley or use exposed
flashing in a valley. They can each work. Some issues are
aesthetic. The continuous flash require more attention to detail,
sealing the bottom of the flashing, cutting back the tops of the
shingles, sealing the shingles.
The step flashing does not require special practices or changing
tools or methods for the roofer.
Keep the whole world singing . . . .
Many roofs are done exactly that way, but with a single
'turnback' on the roof side away from the wall. The flashing is
known as turnback flashing, one of the two standard methods for
flashing a roof that meets a vertical wall on the rake.
I think that the step flashing is better, but they are so close
that I don't really care which one is on my house, as long as
they are installed correctly.
Just appearance. Some people don't like the looks of the flashing,
which would be exposed on top of the shingles. You can't put the
shingles on top of the flashing,because any water running down the wall
would end up under the shingles. Step flashing avoids this problem.
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I assumed that the OP was talking about a rake wall situation and that
the flashing would be under the shingles same as in an open valley.
That's what Bob Allison was talking about as well. The flashing would
only be on top of the shingles if the flashing in question was at the
top of the roof that abutted a wall perpendicular to the pitch of the
Not to mention that you would never use step flashing at that
detail. You would use wall flashing. I am sure that the OP was
talking about on the rake. That is the only place to use step.
I am assuming that Larry is either thinking that this is a
horizontal (non rake) application, or that he has never seen
turnback flashing installed. It goes under the shingles. The
turnback keeps the water from going past the edge of the flashing.
Tell me you didn't really install turnback flashing on top of the
What happens to the rain that goes under it? How did you fasten
it down so that it won't flap in high winds?
In 35 years of roofing, I have not heard that one before. I
should have known it was coming, though.
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