Quick Drip-Edge Question...


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Old 08-06-06, 07:23 PM
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Quick Drip-Edge Question...

I'm getting geared up to re-roof next weekend, and I think I've got everything covered. The only loose end I have is does the drip edge go over or under the ice & water shield. I can see reasoning behind either, but I figure this is a good place for confirmation.
 
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Old 08-06-06, 07:56 PM
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This question was asked in the January 2006 issue of Journal of Light construction. In short, the expert who answered the question said that either method will work fine, although his preference was to stick the membrane to the drip edge at the eves. (which is just the opposite of his recommendation if using felt paper). The basis of his conclusion is that if the self-sticking quality of the membrane is strong, the connection will not leak.

If it did *not* stick, water would be able to penetrate directly onto the sheathing... which is why some roofers and manufacturers prefer to adhere the membrane directly to the sheathing- since that is what it is designed to protect.

In short, if the manufacturer has guidelines, follow them.
 
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Old 08-08-06, 09:19 AM
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Thanks for the reply. I didn't realize this was such a debated thing. I'll see what the manufacturer says.
 
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Old 08-08-06, 05:40 PM
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Yes, it's a huge debate, with installers doing it both ways and no one knowing for sure which way is best. It's similar to the "which comes first- tarpaper or dripedge debate."

Both sides make valid cases.

I prefer to apply felt paper to the edges of the sheathing, then apply metal flashings on top. The metal flashings keep the wind from blowing up the edges of your felt, and any water that leaks behind the metal flashing will run onto the tarpaper. If you apply the metal flashing first, and apply tarpaper on top, any water that gets between the tarpaper and flashing will wind up on the bare sheathing.

In my book, it's similar with self adhering membranes. But rather than give my opinion, I thought I'd mention what the "experts" are saying. But even the "experts" disagree, I'm afraid!
 
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Old 08-10-06, 09:50 PM
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It's debated because it depends where you live.

In the south, where you don't have ice dams, some want the I&W shield to go UNDER the drip edge at the rakes and OVER the drip edge at the eaves. That way, any wind-driven rain blowing in from the rakes will go over drip edge and onto the I&W shield. Then the water will run down the roof and off the I&W shield and off the roof.

Some in the north want the I&W to go under the drip edge at the eaves to protect the roof from ice dams that back up under the shingles.

It is debated, but I really think it depends on where you live.
 
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Old 08-11-06, 07:22 AM
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I'm in the Chicago Suburbs. I'm going to try and call the manufacturer of the I&W later on today and see what they recommend. It's a hip roof, so I don't have gables to worry about, just the eaves.
 
 

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