I am going to roof my house soon and would like to know why some valleys are cut valleys and some are woven. I live in Texas and most every house I see has woven valleys. I lived in another state and most were cut valleys. Is there a specific reason for this?
The best one is the one done right. It is the roofer who makes the difference.
Both work equally well when properly installed and both fail nicely when not.
For my money the woven look a lot better.
I always thought that woven were subjected to ice dams that could cause them to leak where continued thawing and freezing pushes up shingles. I would assume that in a warm climate, you would not need the valleys. Frank
We get plenty of freeze thaws and lots of snow, but I, nor anyone else I know has had any problem with the woven valleys. It seems to be as much of a style thing and more popular in some areas than others as anything else.
Just from a practical sstandpoint, it is faster to lay a 'weave' than an open valley.
Harry K
I agree with Mr. Meehan. On the roofing crew I was on we always used the cut valleys. From my perspective the very wide flashing used would be unlikely to leak and is fast and easy to install. It allows the roofer to tear off and complete one entire plane of the roof while leaving the other plane untouched. This is an advantage in threatening weather or on larger houses. I also suspect it's more durable since the roofing materials lie completely flat on the deck unlike the weave.
Woven shingles are rare where I am in Minnesota and I suspect there are reasons other that preference for this. Our weather is constantly changing and can include snow, ice, and major thunderstorms. The woven is a nice look though and might be cheaper since shingles are cheaper than flashing.
Not a roofer, but am a home owner, so this is just personal preference.
I would have the roofer lay down an ice shield (rubberized self sealing adheasive layer), and then go for the cut valley with 'w' flashing.
I have a fear that if water or snow is given a enough time, it will find a way into the house. So a smooth valley will give least amount of time for snow and water to sit there.
Just a guess....
tom @
Google for: roofing valley woven
The sites I looked at said there's little difference in terms of durability. Woven has some small disadvantages on flatter roofs and with ice dams.
I had my roof redone a few years ago. I used to have a cut valley with aluminum. One of the reasons I had to have the reroofing done was that there were pinholes in the aluminum. I suppose acid rain did it's thing.
I choose woven first based on appearance and second to avoid exposed aluminum as it seemed less durable than the shingles.
Bottom line, I don't think there is a big difference.
seeing how you live in texas I would recommend a "western" cut shingle valley.
there is no difference it is a personal preference.
Good point on the re-roof thing.
Can't agree on the 'faster'. True the flashing goes on fast but then you have to cut at an angle every shingle that reaches the valley and it has to be exact or will look crappy. Woven is a straight cut, doesn't need to be exact and, in many cases, no cut at all is needed on the last shingle per row.
I doubt that there is much difference cost wise as woven requires more shingles and the flashing while more expensive is only a minor cost of the overall job.
Harry K
On our crew we let the shingles at the valley run long. Then you snap a line and cut it all in one pass to look right. The foreman gets to do that job since he is worried about how it will look. Some times he just uses a hook blade utility knife sometimes a pair of snips. anyhow, so long as you stay on the line it will look good just don't score the flashing.
Personal experience (not a roofer, but my family does its own roofs):
We always did 'open' valleys, where about 1' of rolled roofing was exposed in the valley. Underneath, we put sheet metal over the felt, then 18" rolled roofing (face down), then 36" 90# roofing face up, then shingles up to a cut line.
I did my roof that way about 15 years ago. The valleys all failed in
10-12 years, long before the shingles. It was a PITA to re-do them (woven now, for sure). Asking around, the story I got was that this was a general problem - that rolled roofing does not hold up to sun as well as shingles, and that woven was the recommended way to go. Looking at other roofs around here, I see the same thing - (open) valleys failed, shingles OK.These are all relatively steep (40+ deg) roofs, in Syracuse NY.
George
I never heard of doing it that way and can't see any benefit to it. Also I wouldn't call it an 'open' valley. It also sounds like PITA to lay it originally.
Harry K
Yeah, I thought "open valley" meant exposed metal flashing. What's the point of the roll-roofing?
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