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roofing valleys

3115 Views 18 Replies 7 Participants Last post by  jagans
I am planning a screen porch addition with 4/12 gable roof with valleys. When done I plan to re-roof the home and the addition. I have received a number of conflicting opinions regarding the strait edge, metal, or weave methods. I would love to get some input from some expereinced roofers as to which may be best. I lean towards the weave method, but one roofer told me never to use this method with architectual shingles do to their thickness. Your opinions will be greatly appreciated.
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Weave can be difficult to make look good. Closed cut valleys are simple but effective. Metal valleys are more costly but long lasting. I find valleys tend to be the first area to leak, so metal valleys are the way to go.
Thanks Shazapple,
I currently have a pair of valleys on the front of my 25 yr. old home (southern exposure). They started to leak about 8 years ago. It appears that I should not have nailed them securly to the roof when I built the home. Expansion and contraction caused cracks. I was able to stop the leaks with silicone caugh. I do like the appearence of metal but will have to do more research as to how to secure them without restricting expansion. Any ideas?
Valleys were traditionally secured with wind clips, usually just two nails at the very top to stop it from sliding.
Depending on where you live, you may find the clips very hard to find as they have left favor, but they are superior. On a shingle roof with metal valleys, I use 7"x7" 0.024 aluminum, with a fold on the edges for the clips to grab. 1 clip per 12", on each side.
I live in a city of 400,000, and not one supplier stocks them, so I make my own.
No clue where these new posters are from but I've never even heard for "clips" being using in a valley.
No idea where they get the idea where they think a woven valley is so had to do. A simple snaped chalk line to get it straight is not all that hard to get right.
I just lay a layer of storm and ice shield in the valley before installing the shingles and keep the nails back at least 6" for the valley.
I like closed cut, Full sheet of ice dams centered on valley, felt run over ice dams Metal is good, and bad. It moves at a much different rate than bituminous materials. My Partners father used to nail next to the metal, basically so the shank was adjacent to the sheet, then not sink the nail all the way. Clips are good but then you have to hem the edge of the valley.

Frankly, with the advent of ice dams flashing, I think closed cut is the way to go. Metal just moves too much. I just did my roof with Ice dams in the valley and closed cut architectural shingles. Its the way to go.
"No clue where these new posters are from but I've never even heard for "clips" being using in a valley."
They're cleats, not clips Joe. Just a terminology thing.
Cleats eh, not a term that I have ever heard before. Makes sense, cleats it is. Done this way you can skip the ice shield though, I've had 2-3ft of snow sitting on valleys with this method, 15lb in the valleys, full of holes and doing nothing, no leaks.
Closed valleys work great too, and I default to them unless metal is requested.
The cleats are basically little strips of copper bent in an S and hooked to the return Hem on the outer edge of the valley flashing. the outer edge is nailed with a copper nail and the outer tab is folded over the nail. Assuming a copper valley flashing

Thanks to the Sheet Metal and Air Conditioning National Association Manual 3rd Edition. SMACNA (The good old one)


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If you have any chance of snow, ice, or leaves accumulating in the valley then metal is the best way to go. Using minimum 0.032 aluminum you won't have problems with metal moving. If you are trying to save money, you can get 3 pieces or 30 feet of valley from a 48" wide sheet. Better if you break it and get 2 valleys per sheet. So we are talking $20 to $35 per valley, definitely worth it for the protection you get. It is unfortunate more valleys aren't metal.

Weaved valleys are a horrible idea. The NRCA has taken a position against weaved valleys for laminated shingles for years. The one roofer you referred to is correct.

If you don't need or want the metal, then closed cut is the way to go. The cut method doesn't build the roof up at the valley line like the weaving does.

Using the proper material for your metal valleys, they can be laid over your underlayment or ice and water and nailed on the edges. You don't need cleats. Overlap the valley metal minimum 6" with sealant under the lap. You will have to nail the shingles through the metal at the valley, (hence the waste of time using cleats), so you need to keep the nails back 6" or so from the center of the valley.
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" You will have to nail the shingles through the metal at the valley, (hence the waste of time using cleats), so you need to keep the nails back 6" or so from the center of the valley. "

I took GAF to task on this. They replied that if metal manufacturers had different spec, you'd have to go with that. Steel, aluminum, copper and all spec cleats and NO nails in the metal.
Metal expands and contracts with the weather. Always cleat in your valleys if you want them to last.
Im really sorry to have to disagree with you Roofinron, but you should never nail your shingles through your valley metal. You cannot beleive how many failed shingle roofs I have been on where this was the case. Please refer to the NRCA Steep roofing manual. The top corner should be clipped at 45 degrees to prevent underun, and the shingles should be set in flashing cement. Aluminum moves a lot and it will rack the nails back and fourth with temperature change and back them out as it expands and contracts. When you break a diverter into it you have created a structural member that cannot oil can between fastening elements. You can nail adjacent to the pan and not take the nails all the way home. This will allow the pan to slip under the nail heads.

Copper or lead coat for slate, shakes and Tile, Ice dams and closed cut for architectural shingles.

Copper is a better valley metal if you can afford it.

I hope this saves you some grief.
Surprisingly, Revere specs the two nails near the center of the valley to hold it in place. Close together, the metal won't warp, nor slide like one I repaired recently. The nails are are under a 6"-8" lap.


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There are thousands, if not millions, of lnft of valleys that are down without cleats. Many metal roof manufacturers specify installing a joggle cleat in the valleys with fasteners 6" on center down both sides of the valleys. Many are not utilizing any kind of a floating valley with cleats. The metal is expanding and contracting and not falling apart.

I would much prefer to install the 18" valley on a 36" wide HighTemp Ice and Water. I am a 3rd generation roofer with my family roofing in the Tidewater area since the 1950's. I have seen what lasts and what doesn't.

Sure metal does move but a rough number to figure worst case would be about 1/2" per 50 foot. So on a 10' valley stick it moves very little. The important thing with metal work is not to fasten sticks together. They should be allowed to expand and contract independently.

I will pass on setting my shingles in roof cement. All these roofs are water shedding systems not water proof.

My intent here is not to sell my company, but to help a diyer. While I don't think you are wrong tinner, I also don't want to unnecessarily complicate things.

@ tinner - Are you meaning to say the slate roof was leaking because the valley was nailed on the edge? How many years was that valley there?
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@ tinner - I just caught you were referring to the buckling in the old copper with the picture. That has nothing to do with the nailing and certainly didn't cause any leaks. That was the fault of the way they were installed. Roofers were sent out with a copper on a coil (which is softer) and valleys formed in the field using foot tongs or even stomping them in. The copper you use is harder and breaks nice and flat. (I am thinking you already know this.)
The warped valley is SS. I've also seen copper, aluminum, and steel valleys warped.
In each case, I was called to fix leaks. In each case, the open valleys had splits and tears from the constant flexing.
In closed valleys, the constant flexing had split the metal and torn the shingles.

Max width of usable valleys should be 14" which will allow nailing within 6-!/2" of center without hitting the metal. When using small slates, the max valley size is 12". That's 12" metal in the copper pix.
Hi Guys,

I suggest that you pick up a copy of "Copper and Common Sense" Published by Revere Copper Co. and read it cover to cover, twice. It was developed and produced in reaction to the significant number of problems that roofers and sheet metal mechanics were having with sheet metal. It is a very well written and illustrated little book, that will help you enormously, and keep you out of trouble.
Hi Ron,

One of the points I was trying to make with metal, and this is very well documented, is that thicker is not always better. We know that metal moves. Aluminum expands about double what steel does, That is why I spec Kynar coated galvanized steel with return hems, for copings.

If you insist on nailing through your valleys, I would stick with .024" aluminum, not .032". I guess we all have our reasons for doing what we do, but nailing through valley metal causes many of the leaks I find in MD. Maybe where you are you don't get hydraulic pressure too often.

At any rate, Have a Merry Christmas, and stay safe up there.
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