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Chimney Flashing

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Guest User
1/18/2008
I have a chimney in the middle of a small valley on a 4/12 slope. I'm redoing the whole roof. There's about 4' long by 2' to 3' wide of metal between the chimney and the valley to guide the water around the chimney. I plan to use the same patter and maybe make a "W" flash of one piece that goes up to the chimney. I thought about using copper since it wont rust but my father in law suggested galvanized tin. The flashing on the chimney was rusted when I torn it off. No wonder there's water in the basement around chimney. So, I don't want to have to deal with it for another 30 years. What metal do you suggest that will last at least 30 years without worry about it?
Guest User
1/18/2008
Sean, I would make a pattern with the measurements and angle degrees then have a sheet metal shop make a two piece flashing (one for the bottom half and one for the top half that will overlap the bottom piece) out of stainless steel. Make sure that it is tall enough in the back to keep the water that hits it from going up and over it. I usually make the back anywhere from 12 to 18". It depends on the roof pitch and valley run. [email protected]
Guest User
1/19/2008
Sean, Since you are on a low pitched roof, I might suggest you first use "ice and water shield" or some type of "moisture barrier" on the substrate (decking), before installing the new metal. We run it up the chimney a minimum of 6 inches as a precaution. This is self adhering so it's smart to "waterproof" the area before you put in a new "cricket". This is a critical area on the roof and it's unique in that you have the flow of water down (VALLEY), and directly into a stopper (chimney) in the path of that flow. I agree with Wade because a galvanized steel diverter built properly should last 30 yrs. On a side note, your counterflashing is even more critical if you want thirty years out of it. You didn't mention if your chimney is stucco, brick, masonite, or vinyl siding. This matters. Just a little more food for thought. Joe at LastimeRoofing.com
Todd Miller
Isaiah Industries, Inc.
2/6/2008
Sean, let us know how things tuirn out.
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