Flat Roof Drainage

[Greg]

We plan to replace the roof on our mid-century modern home in the SF Bay Area (East Bay). We are considering the same type of roof (tar & gravel), as well as modified bitumen and foam.

We need to also improve the roof drainage. There's currently no gutters, downspouts, fascia board, etc., just flashing around the edges. When it rains, water just spills over the edges in certain places.

Any suggestions on what to do? Our preference would be to put up fascia boards and coordinate some type of drainage solution with the new roof. We're not sure how to go about this, or if we need a carpenter or roofer for this. Also, any contractor recommendations in our area are welcome.

Thanks for any help.

[Tom]

Greg wrote:>We plan to replace the roof on our mid-century modern home in the SF

Ay-yi-yi, flat roofs. Consider the newer materials. And no fascia?? No eaves? So the drip edge is lapped right onto the exterior wall of the house? You'll need something to affix the gutters to, and it's nice to sometimes slip them under the drip edge to get enough fall. You will need to co-ordinate with the roofer, cause they'll have a tough time starting on the roof without the first courses in place.. Tom Someday, it'll all be over....

[Bruce]

You should consider adding parapet walls and draining the roof at scuppers. Done properly, a "flat" roof can be contoured so that it quickly drains to the scuppers and leaves no standing water. You should also consider adding some sort of gutter system that will collect the runoff as it exits the scuppers and discharge it safely away from the house.

[ameijers]

Like the others have said, a contoured membrane roof with either scuppers or drain grates to internal drains, perhaps hidden in a closet or something. Like a small version of a commercial roof. You need professional help, and not a company that just does residential roof reshingles. It'll cost, but done right, you will probably never have to mess with it again. Next to the foundation, the roof is the most important component of the house.

aem sends....

[Tom Baker]

I'd suggest an architect look at the existing conditions and suggest an approach. You could arrange a small fee for consultation. If you feel it is worth it, that could be extended to providing detailed drawings.

The house has been around a long time. The chaotic drainage your post implies would have caused severe damage. There is the possibility that past owners have changed things. Someone with training and experience would be able to see the intended system.

Tom Baker Charleston SC

[<yy#ui]

all "low-pitch" (=flat/ponding) roofs are disasters. designed and built to fail within 15 years.

(%22flat%22)%20roofs&hl=en&lr=&ie=UTF-8&sa=N&tab=wg ask architect (as sugg below) if you can get a standing seam roof. (requires additional shallow framing)

that's the best - if your lot is well drained (rarely is. And east bay is mostly clay). gutter over doorways is all you need.

yes.

maybe not so small a fee, but less costly than teh alternatives. :-(