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TOPIC: Flat Roof

Low slope residential roof 1.5/12

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This 2,800 sq ft one level house has a 1 1/2 per 12 slope roof. The house is in East Tennessee on a wooded lot. The roof has one 22.5 degree valley that results in a 3/8 per 12 slope down the valley. Originally, it had a built-up roof that was replaced with narrowly spaced shingles about 10 years ago. It seems to work when kept very clean of debree but fails in a couple of spots when not clean. I am considering a metal roof replacement. I have several questions, but let me begin with one: On this site and elsewhere I read recommendations that a commercial style (mechanically sealed) roof is needed for such low slope. At the same time, some recommendations say that one should not use commercial products on residential roofs (it voids some warrantees). What is it about commercial style roofs that hinders their performance on residential low-slope applications? I know that it depends on manufacturer, but one or two examples would be good. Thanks! George
Guest User

2/28/2005
In this particular case, assuming that you have solid decking (plywood) down that the metal will be installed over, I do not know of any warranty issues you will encounter. By all means, though, make sure that the product you choose is appropriate for this application and that the warranty is valid. I agree that, if this is to be done in metal (unless the roof pitch is increased) it will require a mechanically seamed system. Todd Miller
Todd Miller
Isaiah Industries, Inc.

2/28/2005
I have a roof with a 2:12 pitch. I was wondering if I covered the entire plywood sheathing with "Ice and Rain Shield" or some other peel and stick membrane, if I could then utilize a standard residential metal roof and have no leak problems.
Guest User

7/19/2006
Regardless of underlayment, you must adhere to the minimum pitch specified by the roofing manufacturer. Todd Miller
Todd Miller
Isaiah Industries, Inc.

7/20/2006