I am planning to build a new accessory dwelling unit (granny flat) in my backyard. I really like this design from https://node.eco/

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However how do I manage the flat roof water run off? Is it just very low pitch or something?


Slope the surface of the roof to one corner - the black surround hides it.

The slope does not need to be much (0.5cm per metre or 1/4" per 3 feet roughly - my guess) but the roof should not have dips in it ie you should not get puddles after rain.

Then organise the downpipe as required.

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  • How come the slope here is so low vs. Shed or regular house? Is this design only for region without snow or tree leaves falling? Because in Pacific Northwest, I collect 5 inches of leaves over Dec on the ground. – HP. Jul 22 '19 at 21:50
  • @HP. So you think houses with a 60 degree sloping roof are designed for the rainfall? Roof designs tend to be down to what the local carpenters understood - which in some localities meant they used a ship construction upsidedown... – Solar Mike Jul 23 '19 at 4:07

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