Question About Nailing & Layering Of Top Flashing

Chunkstyle

hi guys

with top flashing, where the roof slope abuts a dormer wall, do you nail through the exposed leg of the flashing (the part laying on the shingles)
& then cement the heads, or do you only nail to the wall up under the siding
& use cement to hold the flashing down to the shingles?

also -- one book i was checking out showed top flashing as actually being 2 separate flashings -- one layer under the shingles and another flashing layer over the shingles once you've run them up to the wall -- kinda like flashing & counterflashing.

is this standard practice, or do most people generally only do the exposed layer of top flashing?

thanks!

jproffer

I don't nail down the bottom side. Just tar it on top of the shingles. I figure nail holes down there is just asking for trouble.

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Jim P.

AaronB.

I do not nail roof-to-wall on the shingles, nor tar it down. If you use a heavy gauge aluminum, say .030, you will not need to, if you make the correct bends.

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wickedcarpenter

The nail goes into the top of flashing nailed to roof. Then another shingle and more step flashing that covers your previous nail that went into the roof.
I NEVER nail step flashing to a wall.

Brent

jproffer

that may very well be....but he's talking about top flashing....not step flashing.

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Jim P.

Glasshousebltr

If you decide to use cement beneath the flash (I never use cement unless absolutely necessary) be sure to keep the cement out of the shingle key way. That way if water ever does get behind the flash you don't dam it and create a leak.

Bob

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Bob

dougger222

I nail over the top of the flashing every couple feet and never use tar underneath. On tear offs I'll go ahead and put some sylicone over the exposed nails.

Of the few hundred new roofs I've done this way there has been no issues and of the several thousand new roofs my fathers done this way he's never seen issues.

It isn't a bad idea though to use sylicone over the nails on any exposed flashing.

Tar under the flashing and over the shingles would be a real paid when it's time to tear off the roof.