Drainage Solution for Flat Roof built into Hill?


Old 11-08-17, 11:33 AM
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Question Drainage Solution for Flat Roof built into Hill?

I am wanting a quick-temporary solution to drain run off from my flat garage roof away from the house before the ground begins to freeze/winter hits.

The problem: I have a flat roof over my garage and the rear and right side of the garage is built into the slope of a hill. Currently the roof system is EPDM and not adequate for heavy rains (puddling and bubbling are occurring and there is likely a negative slope so water has no where to go).

I'd prefer to squeegee off excess water until I can get a better roof system in place (I've tried an automatic pump to remove water and it was more time consuming, thus useless).

However, when I do this, the ground along the foundation gets soaked and creates a waterfall down to my driveway (which is slopped downward from the street, thus I'm left with another puddle elsewhere-looking at a channel drain for this issue).

I am wondering if there is anything that can be done to move the water flow away from the foundation around my garage that can be done quickly (a few hours) until I can get someone out to fix the drainage issue next year. All the DIY french drains and such seem too involved for the time I have before snow begins to fall.

I was thinking of creating some kind of trough along the roof line that can feed out away from the house and down the hill furthest from our garage/driveway (like a small waterfall). Not quite sure what materials I would need to implement this and if the investment doesn't make sense so close to Winter?

Any feedback is appreciated!
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Old 11-10-17, 06:43 PM
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A few pictures would help us see what you want to do
Old 11-13-17, 05:45 AM
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Hopefully these images help?
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Old 11-13-17, 06:14 AM
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Well, first off, the beauty of epdm is that it is supposed to be waterproof. If you have a few puddles of water standing on the roof, it should not matter... as long as it doesn't leak. Does your roof leak? If not, then there is no problem and you should quit going on the roof to squeegee it off because you are likely to tear it or make more areas separate from the underlayment. If it does not leak, there is no imperative problem that can't wait until spring. Staying off the roof is the best thing you can do.

Secondly, I don't see any gutters / eaves troughs / downspouts. So it is no wonder you are getting water against the foundation. Water from the roof is normally caught by the gutters and is carried some distance away by the downspouts or by underground drainage. Adding a gutter to the bottom edge of the rubber roof might help catch that water and at least keep it away from the corner with the patio door.

And finally maybe the pictures are misleading, but the whole area from the far left side of the roof to the far right corner of the picture looks quite flat, where water could pond. Water needs some slope in order to drain away from the house... usually a 1:10 pitch is recommended. 1 foot of drop in the first 10 feet, to get water away from the perimeter of the house. So that is a grading problem.

If water is penetrating the walls in that corner, that would be an issue with waterproofing... and the walls should be excavated, repaired, and waterproofed.
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