Installing new valleys


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Old 03-31-06, 04:22 PM
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Installing new valleys

I was wondering if any one could tell me the rules to installing metal valleys, as in when installing the shingles how far in the valley i should start and where i will end up in the bottom such as 1/8 per foot of drop. Thank you very much
 
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Old 03-31-06, 04:51 PM
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I'm guessing that you are asking about how to shingle an open metal valley?

First, the roof should be papered. Personally, the first thing I like to do is run 30# felt down the center of the valley, step it down, and nail the edges. Then when I felt the roof, I run the first course of tar paper past the valley. Then I switch to the other side, and run that side past the valley. Alternating sides like that creates a woven valley that will not leak. I then lay the valley tin on top of the tar paper and nail the edges. (use only W-style valley tin) It's important to remember that when you lay the shingles, you should not nail within 8" or so from the center of the valley.

Once you have shingled up the valley, if you are doing an open valley, you chalk a straight line from top to bottom, and cut the shingles with a hook blade. I like to begin the cut at the top, about 1 1/2" away from the center of the valley and finish at the bottom 2" away from the center of the valley.

After the valley is cut, go back and cut the tips off the shingles. The idea is to eliminate the sharp "point" off the top tip of the shingle so that it does not catch water and direct it back along the top edge of the shingle.

If this doesn't answer the original question, just clarify, there's plenty of roofers here and plenty of advice.
 
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Old 03-31-06, 05:02 PM
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Thank you XSleeper, Here is the situation I am in. The roof on my house was replaced in 2001 prior to my purchase in 2004. I noticed last year that my sheetrock in the dormer was wet. I had a guy come look at the roof and he said the valleys were not installed properly, the person who installed the roof tried to use a closed valley system. He did not put any metal of membrane in the valley just 5 layers of roofing felt(so he claims) So what I am plannig on doing is removing the shingles, installing the weatherproof membrane and installing metal on top of the membrane the install new shingles in the valleys. I am hoping that this will fix my problem. Any insight would be appriciated. I am kind of flying blind on this project and hope to not get my self into a bigger mess. I was just wondering if you should make the valley wider at the bottom and if there was a rule of thumb, thank you very much.
 
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Old 03-31-06, 05:17 PM
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Closed valleys do not need metal valley tin, and if installed properly, will not leak. I wonder what is causing the leak? I once had to find a leak in a closed valley ("california valley"). The wet drywall turned out to be about 10 feet away from the location of the roof leak. The source of that leak was a seam that fell too close to the center of the valley. You might walk up the valley and look for something similar.

Sometimes people who install a "california valley" (one side runs long through the valley, the shingles on the other side are cut straight alongside the valley) sometimes they will have the cut side lapping the wrong way. (The side of the roof that has the most runoff should be the side that is cut... the side with the least runoff would run up and under the cut side of the valley.) When it's lapped the wrong way, large volumes of water might possibly force their way up and under the cut side, where it could potentially cause a leak.

Perhaps your valley is woven? One side under, then the other side overlaps that one, and so on. Maybe the original roofer just did not overlap a shingle far enough?

Have you been able to get up in the attic at all to inspect for the source of the leak? Leaks often will follow along a valley rafter or jack rafter before finding a spot where it drips down onto the sheetrock. And with drywall, the leak can often travel some distance before it shows up at a seam.
 
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Old 03-31-06, 05:53 PM
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Both of the valleys are leaking the same way, one is not as bad as the other, I looked at my roof and the cut line is on the side of the roof that is exposed to more water, I belive that is the reason it it leaking like they are. I tried to raise the cut shingles and run a bead of roof caulking and that slowed the water pentration but they still leak, I am just wanting to fix the problem instead of putting a band aid on It. Am I headed in the right direction in replacing the valley and installing a membrane and metal?
 
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Old 03-31-06, 06:10 PM
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I would skip the metal. If you're installing a self-healing membrane (36" wide), the metal (14-20" wide) is pointless, unless you really want an open valley.

I'd tear it out, and reshingle it using a california valley, but lap the shingles so that the majority of runoff runs off the cut edge, rather than under the cut edge. That's my 2 cents.

I'm sure others will chime in and voice their opinion as well.
 
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Old 03-31-06, 06:19 PM
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I am just kind of weary with the california valley. I dont want to repair the roof and it leak again. Will the metal give me any back up protection or as you said just a waste of money?
 
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Old 03-31-06, 06:31 PM
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Metal is used in open valleys because thats the way it was done 100 years ago. Now that there are other products that are a). wider and b). self-healing when you put a nail through it, metal valleys are a dying breed. Many people feel that closed valleys have less of a chance of leaking, because an open valley is open on BOTH sides. Your california valley is open on one side, and you can control how far the other side runs underneath. You could run it 2 ft up the other side if you wanted.

The membrane is your backup, I'd say the metal is a waste of money (if doing a closed valley- california or woven, either way). But if you are doing an open valley, the w-style metal valley is a must. You would still use the membrane as a backup.

Not sure if the original roofer did this with your valley or not, but on the "cut side" of a california valley, you can run a shingle upside down (top edge toward the valley) the length of the valley. Keep it 2" up from the bottom of the valley so that it's bottom edge is above most of the runoff. then rather than "cutting" that side, the shingles start from that upside down shingle and go away from the valley.

If you replace the valley and it leaks again, I'd say that your leak is coming from somewhere else!
 
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Old 03-31-06, 06:43 PM
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Thank you very much for your help XSleeper. I am will look into the california valley If the membrane will stop the pentration then like you said metal is a waste. I am sure the california method will be easier due to only one cut. As I said earlier I just want to fix it right and wanted to make sure I was on the right track.
 
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Old 03-31-06, 06:52 PM
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Glad to help. Keep checking this thread to see if there are other opinions in the days ahead.
 
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Old 03-31-06, 07:10 PM
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hopefully they will post before tommorow morning, because that is when I will be trying to fix the problem. Thanks again.
 
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Old 03-31-06, 07:31 PM
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We run California valleys (or as we call em "cut valleys") here in Arizona. the 3 most common errors is (1)not cutting the points off the top of the shingles on the cut side.

From XSleeper
"After the valley is cut, go back and cut the tips off the shingles. The idea is to eliminate the sharp "point" off the top tip of the shingle so that it does not catch water and direct it back along the top edge of the shingle"

(2) Piecing a tab in the valley instead of running a full shingle across the valley. Look at your valley to see if any of the end joints of the shingles (butt ends) are closer than 12" from the center of the valley.

(3) Not cutting the cut side a little up out of the valley. If the cut side is in the water flow area, any little debris can send the water sidways.

I agree with no metal. Just make sure you install full shingles across the valley. If I were going to the troble of tearing the valleys out, I would install at least a new #30 down the valleys first.
 
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Old 03-31-06, 08:11 PM
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Hooter, You said you would install atleast a new #30 down the valley does that mean on top of the membrane? Also you guys have said cutting the points off the top of the shingles I am not sure what that means, the material is a timberline shingle could you please explain.
 
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Old 03-31-06, 09:01 PM
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Ideally, the new #30 should go UNDER the existing felt or membrane. You may find that not possible due to type, amount, method of install, condition, etc. So, I would install it on top with only enough nails at the eges to hold it in place.Careful and try not to damage the existing. NO NAILS IN VALLEYS !

Ok, the points can be explained as follows: Take a shingle and imagine cutting it to fit on the cut side of the valley....Basiclly, you will cut it from the top edge down to the bottom at an angle...... The angle will create a point or tip on the top edge....Those lil boogers stick in the valley and can catch water and run it sideways...... Shingles are desighn for water going downhill, not sideways......

The #30 is absolute minimum.....Heavier is better if you want you could install a modified roll material....Tuff stuff but not sure if Lowes or the like carry it.....
 
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Old 04-02-06, 08:55 AM
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Wow, I opened up a can of worms. I was able to get on side of the valley done yesterday. We tore out two full lengths of shingles on each side and were able to lay the membrane on top of the felt (the installer ran 5 layers of felt underneath the leaking valley) and then add metal on top of the membrane, I know you guys said it was a waste to lay metal. It just worked out better that way.(the valley was 21 feet long) I'm not sure what the pitch was but my legs sure are sore. I found new respect for the roofing trades, We had a good rain last night and I checked the valley and there was no signs of water, I guess only time will tell. Thanks for your help, next weekend I will tackle the other side, only problem is this side doesnt have a landing at the bottom of the valley so it might be kind of a pain, I might have to set up some scaffolding to catch all the shingles and tools that slide off. Thanks again
 
 

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