Best valley flashing for dimensional shingle roof

[t.p.bernhardt]

Gurus:

This summer we plan to replace our 24 year old shingled roof with long-lasting dimensional shingles.

Contractors are pushing two schools of thought for the valleys.

1. Use pre-painted metal flashing. (This is what we have now.)
2. Use close cut shingles in the valley.

Which process would you recommend for the longest-lasting roof?

Thanks for your thoughts.

Tom Milwaukee, WI

[Robert Allison]

An extra layer of 30 pound felt in the valley, then 24" wide rolled valley metal, then lace the shingles in the valley (closed valley). The roofer may balk at lacing the shingles, but it is the best method, so insist on it, unless you have different slopes on the two sides of the valleys. If slopes are different, then go with the cut closed valley.

[Dan]

Good people may differ on this. I think that a laced valley would look pretty coarse with dimensional shingles, and the valley shingles tend to wear much faster than the rest. I would use a metal valley, copper if you can afford it, and cut the valley narrow from both sides. Juse my opinion, and the way I've done it with this type shingles.

Dan

[Robert Allison]

Dan could be right. I have no experience on northern roofs. Just on southern stuff. I know that there are significant differences in building methods between yankees and southerners. Down here it is hard to find an open valley, except in tile or metal roofs.

[Oscar_Lives]

Use HD rubber underlayment and just cut the shingles for a closed valley.