roofing and flashing question

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.
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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.
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gntry wrote:

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.
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says...

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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wrote:

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 roof.
R
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RicodJour wrote:

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.
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Allison) says...

Makes a lump under the shingles if you do it that way. Step flashing sheds the water on top of the shingles with every course, and is invisible when properly installed.
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Larry Caldwell wrote:

Tell me you didn't really install turnback flashing on top of the shingles. Please.
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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Allison) says...

OK. I don't install turnback flashing on top of shingles. Now you tell me the turn back doesn't make a lump under shingles.

That's why you use step flashing, and interleave it with each course.

After 35 years on construction sites, your hearing isn't what it once was. You seem to be imagining things.
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Larry Caldwell wrote:

Thank god. I was not willing to believe that someone would do that. Doesn't really make a lump, more like a gentle rise. Hardly noticeable from the ground. Most people cannot even see it.

I am so glad to hear this. I was worried.

And I am glad that that is what it was. I am not the only one that had that same thought, though. Per Ricos post.
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try www.therooftech.com
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Try www.therooftech.com
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try www.rooftech.com
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try www.rooftech.com
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