Anyone have a good reference for the maximum amount of slope allowed in a stair tread? My Library says ¼" but I don’t know where I got it. Nothing in IRC or IBC that I could find.

For outdoor stairways, treads must be slightly sloped so water will not accumulate on the stairs. Install a 1% slope (1/8 inch per foot) to ensure water runoff but do not exceed the maximum allowable slope of 2% (1/4 inch per foot) in any direction.

Hope that helps.

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R311.7.7 Stairway Walking Surface
The walking surface of treads and landings of stairways shall be sloped not steeper than one unit vertical in 48 inches horizontal (2-percent slope)

1 inch (or 2% of) every 48" or 1/4" per foot.

IRC R311.7.7 Stairway walking surface. The walking surface of treads and landings of stairways shall be sloped not steeper than one unit vertical in 48 inches horizontal (2-percent slope).

IBC 1011.7.1 Stairway walking surface. The walking surface of treads and landings of a stairway shall not be sloped steeper than one unit vertical in 48 units horizontal (2-percent slope) in any direction. Stairway treads and landings shall have a solid surface. Finish floor surfaces shall be securely attached.

Yup, anything more than 2%, you fall on your a ss and break your tail bone. LOL

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Off topic Kenton, but i noticed your fraction of “1/4” in your thread looks different. How did you get it to look that way?

Jeeeez, I must be going blind! I looked through that section of R311!

It did that for me, Neil. Word often does it too, for ¼" and ⅛". I think putting the " sign must help.

If typing on a Samsung device, just hold down the number key & options pop up.
Here’s a screenshot of what it looks like.

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Or ¼,½,¾ alt 0188, alt0189, alt0190 on a regular keyboard.

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For residential buildings, the minimum tread depth shall be 10 inches. … For outdoor stairways, treads must be slightly sloped so water will not accumulate on the stairs . Install a 1% slope (1/8 inch per foot) to ensure water runoff but do not exceed the maximum allowable slope of 2% (1/4 inch per foot) in any direction.

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### Troubleshooting: Stair Treads and Slopes| Concrete …

Nice, thanks Brandon