Accessible ramp dimensions

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mermann

November 29, 2021 20:07

The maximum slope for an ADA ramp is 1:12 with uninterrupted runs no longer than 30’ (that rise no more than 30”). . . beyond that point the law requires landings; maximum cross-slope for an ADA ramp is 1:50 or 2%. Floor surfaces sloped 1:20 or less are not considered ramps, and do not need railings or landings Landings for straight runs must be at least 5’ long and as wide as the ramp, landings where people will be turning must be at least 60” by 60”. (See here https://www.youtube.com/watch?v=NqgbL7H6Ujk for a video I made).

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  Christian Strom March 01, 2022 19:56

  Hi Michael,

  A question about cross slopes just came up in a practice exam I was taking. ADA 405.3 states "Cross slope of ramp runs shall not be steeper than 1:48." My local code is slightly stricter and requires a max 1:50 cross slope. Effectively, these are both 2%, but if asked on the exams about ADA requirements, I believe 1:48 would be the correct answer. Just wanted to point this out and ask if I'm missing something. Thanks.

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  mermann March 01, 2022 20:23

  Sloping concrete is nowhere near that precise, so the difference between 1:50 and 1:48 is like measuring the distance between New York and LA in INCHES and getting two different (but close) numbers. They are effectively the same thing (but can be found written as 2%, 1:50, or 1:48 in various publications).

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  Kirill Aleksandrov March 06, 2022 20:03

  Information provided here isn't quite accurate - there is no length requirement from I can see (only height), landings at the bottom are longer than intermediate/top landings, and the cross-slope is called out in the code as 1:48, unless local folks require a flatter slope.

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  bowermb March 06, 2022 22:18

  If I understand your comment about there being no mention of length requirements, Michael is simply relating that max slope of 1:12 to the max rise of 30", which equates to a max length of 30'. At 1:12, every 1" in rise requires 1' of run.

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  Kirill Aleksandrov March 06, 2022 23:53

  That's exactly my point - it is important to read how the code is written - the limiting requirement by code is 30-in height - if the slope of the ramp were less steep (say between 5 and 8%), you would get a longer run, therefore, 30-ft is not a maximum length requirement - it is only true when calculated as max slope and max height, so calling out 30-ft max length for a ramp is misleading, because it only applies to one case... and it actually represents minimum length.

  That's of course unless I missed a provision that does have actual max length restriction somewhere... in that case I take everything back.

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  bowermb March 07, 2022 00:06

  I think that was the assumption, based on his comment. Maximum and minimum are relative to what you're referring to. It's the max uninterrupted length when designed at 1:12. And for the purpose of the ARE, understanding those limits are what's critical - which I believe was his point. I'll let him chime in if he meant something different by it though.

  Regardless, it's important to make that distinction. I understand what you mean.

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