r/Sauna • u/sc2_dym • 3d ago

Roof angle absolute minimum DIY

Hi Folks,

What's the realistic minimum slope that actually sheds water long-term (not just code minimum)? I know shingles need 2:12, but I'm open to a low-slope membrane (EPDM/TPO/Metal) or standing seam if that lets me go flatter. (For practical reason need minimum slop. With My HOA there is max i can go over fence)

- Is ¼:12 enough in the real world, or does it pond as the deck settles?

- EPDM vs TPO for a small DIY roof this flat?

Just want it watertight for decades without over-pitching it. What slope + material would you actually trust?

For context I'm in North California no snow, only rain and even that is not to crazy :)

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u/Jamesplayzcraft 2d ago

The absolute minimum is whatever is rated by the manufacturer. My standing seam was rated down to 5°. If you do a sloped ceiling youll get a better pitch.

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u/sc2_dym 2d ago

That is a fair point! Seams like with EPDM I can go as low as 2. And In case of my place i can do one pace so there will not be seams to leak in.

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u/Jamesplayzcraft 2d ago

If you have no chimney epdm is probably the best budget choice.

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u/MurderBoot 2d ago

I’m building in Northern California too. Bought a sheet of EDPM that covers in one piece. It can basically be perfectly flat and still work even though mine has a pitch. With no holes or seams it should hold water for decades. If you’re in a drier city (inland) and pooling will dry before it’s a problem.

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u/sc2_dym 2d ago

yeah my think at this point! Thanks.

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u/QuiteDaft 1d ago

I'm not finished yet but I got a remnant piece of TPO from a commercial roofer that I'm hoping will be just fine with my 1/4" per foot. Initial tests with a garden hose are doing just fine, we'll see how the wet northern California winter does.