I have to roof a small addition I just finished. I have 2 questions. It is a 3/12 with 2 valleys.
Should I flash the valleys with aluminum and then shingles?
Would felt paper under the flashing be good, or the peel and stick membrane under the aluminum?
Also, with it being cold, would I be better to wait for warm weather so the shingles will adhere to each other, and lessen the chance of them breaking.
Thanks for the help,
Have a good Holiday!
John
Replies
That sure will be a low sloped valley.
I'd use ice and water shield rather than flashing.
I'd also go ahead and shingle the thing now. The shingles should be fine in the cold weather.
If you're in a cold area, tar each shingle tab down as instructed by manufacturer. They will not self-seal in cool weather and tabs may break off by lifting in high winds.
I consider 3/12 too low a pitch for shingles
If forced to do that job I would run a strip if ice gaurd down the valley----and then a strip on each side of the valley------- in fact most likely I would icegaurd the entire 3/12 deck
If it's cold-----say under 40 degrees or so--- I would certainly use an exposed metal valley flashing instead of a shingled( california cut ) valley.
Even on a 3/12---in cold weather I would not want to crack the shingles bending them through the valley
Remember---a valley carries A LOT of water---it has to be done pretty nearly perfectly--------and even one cracked shingle in a valley is gonna come back to haunt you.
BTW---dimensional shingles particularly difficult to lay tight in a valley in cold weather---all the more reason to use an exposed metal valley.
good luck, Stephen
Aluminum makes lousy valley flashing-it's too easily torn and cracked.
Hazlett made a sound choice for full Ice and Water Shield over the deck-then use copper,stainless or galvanized for the valley stock.
Shingle now and leave 6" of exposure on each side of the valleys center.This would mean using 2' stock to bend for your valley.
If your shingles cut poorly due to the cold-use an old pair of tin snips .
Your profile doesn't say where you are so your cold might not be as extreme as other folks roofing now.
I am in the Chicago area.
I was assuming since it was shingles on a 3/12 slope, you had read the manufacturer's lit. They usually require a double layer of "offset sealed tarpaper" or "ice and water shield"/or similar on the roof from 4/12 down to 2/12.
3/12 is too low of a pitch for northern roofs so definitely use I&?W on the whiole thing.
I like exposed metal valleys over woven ones, especially in cold weather that might crack them. I hate AL for valley metal. I have seen it corrode in five years to be so brittle I could poke a finger through it.
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