Low Slope Roofing Options

Answered by Jeffrey ~ December 23, 2010 ~ Comments

I have a client with a 2/12 pitch roof. The previous homeowner had install arch comp roofing shingles in a 350sq ft area. This area has failed and needs roofing and structural repairs. She doesn't want a roof with differing materials and doesn't like the look of Torch Down. Is there a way to laminate shingles over Torch Down? Is there a value engineered and aesthietic solution to her problem? Thanks!

Ryan G. ~ Seattle, Washington

Jeffrey Anderson

Hi Ryan, It doesn't surprise me that her shingled roof would fail if it only has a 2/12 pitch, especially with all the rain that Seattle, Washington can get. I have never seen or heard of standard roof shingles being laminated to a torch down roof, but that doesn't mean it couldn't be done. I would think that it could be a lot of trouble though as just about any adhesive that didn't damage the rubber membrane would eventually fail and after every strong wind there would probably be shingles scattered around the yard. I would also be concerned with voiding the torch down roof warranty by attaching another product over top of it.

The whole point of most roof systems is to get the water off the roof before it has a chance to leak into the home. Low slope roofs create a problem with achieving that objective so products like EPDM and rubber membranes are more waterproof than standard roof shingles as the water will be sitting on a flat roof for a longer period of time. Adding shingles over top of the rubber is just going to complicate the issue. Since your customer is having to pay for the repair of structural damage caused by shingles on a low slope roof, I would hope she could be convinced that she can only expect more of the same without using a product designed for flat roofs.

I would have two suggestions that may help. Would it be possible to increase the roof pitch of the area where the flat roof is located? I know some areas of homes have flat roofs because there is no choice, but in other cases the roof is flat because that is the style the architect or designer wanted in that area. If the latter is the case with your customer's roof, it may be possible to have a local Seattle architect do a simple design that adds some rafters or trusses to give that area a steeper pitch and allow the use of the same roof shingles being used on the rest of the home.

My other suggestion would be to switch to a metal roof. I think this would be pretty expensive, but you might want to look into it. Most snap together metal roofs require a 3/12 or 4/12 pitch to work properly and keep water from entering the home, but a metal roof that is professionally seamed on site can be used down to a 1/12 pitch. A metal roof might blend in better than a rubber roof and your customer might go for it or depending on how large the home is, she might consider metal on the entire home.

Those are my only thoughts on your dilemma. You might want to contact some other roofing contractors around Washington to see if they have any suggestions on how to make a shingled roof work over top of a torch down application. They may be aware of a solution I'm not. Good Luck!

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