Which valley metal installation is superior?

[Brandon Whitmore]

I am studying the W valley metal installation instructions from both Certainteed and Pabco. They have conflicting info. , so I am curious as to what you guy's consider to be a better installation.

Pabco requires a min. 24" wide valley metal, with no nails penetrating any of the metal (or within 2" of the edge on their valley on their technical sheet). They require cleats or nail heads to secure the edges down, and I guess just the tar seal at the valley edges.

Certainteed specifies the need for a min. 18" valley metal, and just don't allow any nails within 6" of the valley center line.

What do you guy's think?

I did some consulting, and am now doing daily inspections for a client having a Pabco roof installed, hence the reason for looking into all of this.

[Jim Katen]

I am studying the W valley metal installation instructions from both Certainteed and Pabco. They have conflicting info. , so I am curious as to what you guy's consider to be a better installation.

Pabco requires a min. 24" wide valley metal, with no nails penetrating any of the metal (or within 2" of the edge on their valley on their technical sheet). They require cleats or nail heads to secure the edges down, and I guess just the tar seal at the valley edges.

Certainteed specifies the need for a min. 18" valley metal, and just don't allow any nails within 6" of the valley center line.

What do you guy's think?

I did some consulting, and am now doing daily inspections for a client having a Pabco roof installed, hence the reason for looking into all of this.

I've always wondered why the requirements don't change with the pitch of the roof.

Pabco's requirements seem like overkill for our region. On the other hand, I'm not sure what the point is to using metal that runs 9" up from the valley center if you're going to allow nails in the last 3".

- Jim Katen, Oregon

[kurt]

WR Grace IWS under the metal is more important than the metal, imho.

I'm a "no nails in the metal" guy.

[Chad Fabry]

I don't like nailing flashing either but I don't hesitate to nail through a valley flashing > 6inches from the center. The only reason to cleat or clip the valley to is prevent oil canning.

Water runs down hill for the most part, a properly detailed shingle prevents horizontal migration.

Pretend my fingers are scissors and cut that bit off.

Metal roofs and slate roofs excluded.

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[Jeff Remas]

I don't like metal valleys period. I would rather see ice and water with a weave or the shingles cut in.

[Jim Morrison]

Pabco is conservative, but then, can you really be too conservative with a valley? Not in New England. IWS beneath it all for sure.

[Scottpat]

I never see metal in the valley, it is all IWS and then the valley is either woven or cut.

[Tom Raymond]

If there is a choice, I'd prefer to skip the metal. If you must use the metal pan; defer to the manufacturers instructructions, and personally I'd extend IWS under lay beyond the edges at least as far as the spec for nailing is in from the edges. IWS is cheap insurance.

Tom

[Brandon Whitmore]

IWS is being installed beneath the valleys, but that really won't matter much if there are no valley penetrations; IWS just widens the valley slightly and is a back up for screw ups in my opinion (in this area)

I'm not really sure that Pabco "requires" any specific valley installation. They end up saying that their way is not the only way, blah , blah, blah in their valley installation guide. Makes me wonder whether I should just stick to Certainteed's instructions while inspecting this roof. As long as they trim the corners and tar seal them to the valley, I don't see a problem, especially on a steeper sloped roof as is the case on mine.

Download Attachment: pabcoapplicationinst..pdf

182.42 KB, but then change their instructions slightly in the valley specific guide:

Download Attachment: pabcovalley.pdf

534.84 KB

Thanks for all the info/ opinions.