Open valley for wood shingle roof
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Jack S



Joined: 30 Sep 2007
Posts: 9
Location: Rhode Island

PostPosted: Sat Oct 06, 2007 6:48 am    Post subject: Open valley for wood shingle roof Reply with quote

I am installing a wood roof on my house which I have done before but I am dealing with an open copper valley for the first time. I am going to have the valley made out of copper.

Here are my questions?

The pitch is a normal slope - about 35 - 40 degrees. How wide of a piece of copper should I start with. What is the total amount of exposure I should leave for the open valley- please define this as exposure of total copper in the valley showing adding both sides up together. The pitches of each roof on each side of the valley are about the same.

Finally I saw a diagram on old house web showing the use of a bevelled wood cant strip running paralell(sp?) to the valley on each outside edge along the entire length of the valley. what is the purpose of this strip and which way should the bevel (the tapered edge) face?

I am using cedar breathe under my wood shingles. Should this extend under my valley as well and if I use the cedar breather should I still use the bevelled cant strip?

I certainly would appreciate any help.
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steve demetrick



Joined: 15 Oct 2007
Posts: 26
Location: Wakefield, Rhode Island

PostPosted: Mon Oct 15, 2007 9:43 pm    Post subject: Reply with quote

Jack, first I have to ask where in RI are you located? Also, what type of shinlge are you installing? If you are using western red cedar, it is common practice to use lead coated copper for flashings, as the tannic acid in the red cedar can quickly corrode the bright copper, especially in valleys, as opposed to a cap flashing over a window, due to the quantity of running water. I'm assuming you are using 30# tar paper under the shingles as well as the cedar breather. Ice and water [shield] is unnecessary under a properly installed wood roof, especially a 10 pitch. The sequence would be to install the valley first, tar paper laps over the valley, lay down cedar breather, install shingles. With an open valley, tar paper and cedar breather is obviously trimmed and covered by the shingles. With the actual copper work, I'm not an expert, but from paying attention to my copper sub, the total valley width is about 16" wide, 8" on either side of the bend. In addition, the edges of the valley are folded over to recieve clips that hold the valley in place. The idea, especially with a long valley is to minimize the holes in the valley (some shingle nails will inevitably get through), but not to nail the metal hard to the roof, as the metal wants to expand and contract with temperature changes. The folded edges also keep water that's running down the roof from running back up under the shingles, as a w-style valley is designed to do. The shingles will cover most of the valley at the highest point on the roof, leaving about 3-4" total exposed. The cut line of the shingle should taper gradually away from the center of the valley as you go down to the first course at the edge of the roof. The taper is subtle, maybe a 1/2" every 10 feet, the idea being that in heavy rains, you need more room for running water as you get closer to the gutter. I hope this is a good starting point for you. As I said, I'm not a professional copper man, but if you want it straight from the source, I could put you in touch with the fellow who does my work. Good luck. -Steve
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Jack S



Joined: 30 Sep 2007
Posts: 9
Location: Rhode Island

PostPosted: Tue Oct 16, 2007 2:51 pm    Post subject: Open valley for wood shingle roof Reply with quote

Steve thanks for all of your advice. I will follow everything that you said. Are you certain I should go with the lead coated copper? I haven't ordered it yet. I did order some lead coated drip edge already. Your advice was really helpful.

Jack
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steve demetrick



Joined: 15 Oct 2007
Posts: 26
Location: Wakefield, Rhode Island

PostPosted: Tue Oct 16, 2007 5:44 pm    Post subject: Reply with quote

Jack,
Are you using red cedar shingles? If you are, I would definitely use the lead coated copper. Where are you ordering the metal work from? If you need a local source, I highly recommend John Abrahamson of Custom Fab sheet metal (788-0797), he's located near me in Wakefield. In the Providence area, Providence Cornice Works on Broad st. (467-7227) is run by Andrew Panciotti, who specializes in historic copper work.
take care, Steve
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