Access Aisle allowed slope tolerance

[ADAguy]

Construction tolerance may or may not exceed 2%?
Would you consider 2% vs 3.5% for distances less than 10' to be a barrier?
If no vertical changes exceeding 1/4 - 1/2" in surface wouldn't it meet concrete flatness tolerance test?
Isn't an access aisle a path of travel whose slope may not exceed 5%
If 2% equals 1" in 20' ( 1/2" in 10') then the difference between 2% and 3.5% would only be .18, .18 ='s < ? difference

 

[e hilton]

I don’t think 2% is 1”/20 ft. Isn’t that 1/(20x12) or 1/240 or .00416?

 

[Yikes]

2% = 1:50 = 2"/100", which is 2" rise in 8'-4" of run, which is 1" in 4'-2" of run.

ADAS/CBC 11B-304.2, 403.3, 502.4, etc. say maximum is 1:48, which is 2.08%, slightly steeper than 2%.
For a 10' length, a 1:48 maximum is 2.5" height.

ADAguy, please clarify: when you say "access aisle" do you mean a "parking stall access aisle" in 11B-502.3 (1:48 max), or do you mean an "aisle accessway" in 1029.13 for assembly spaces, where a 1:20 main-slope and 1:48 cross-slope is permitted?

In any case, the standard for measurement is a 2' long smart level.
Here's where it gets interesting: although there is no written "construction tolerance" that allows slopes in excess of 1:48 on the construction, there are variances/tolerances on the accuracy of smart levels used to measure the construction.
As a result, Evan Terry Associates - the court-approved Neutral Accessibility Consultant for City of Los Angeles - has recently told the City and the court that when they inspect public housing facilities they will accept slope readings on smart levels of 2.3% or lower as being in compliance. They will only cite cross-slope or "level" area if the smart level reads 2.4% or higher.

 

[Paul Sweet]

2% is approximately 1/4" per foot, which would be 5" in 20 ft.

 

[ADAguy]

1. access aisle running slope for accessible parking
2. I appears that ADA sees an access aisle as manuvering space, therefore the 2%?
3. even so, if 3.5 % in 18' (< 5%) running slope, how is this a barrier? Technical violation but an actual barrier?

 

[Yikes]

From https://www.ada.gov/reachingout/barrier.html :

• "Architectural barriers are physical features that limit or prevent people with disabilities from obtaining the goods or services that are offered."

The word "limit" means that in practice, the definition of an architectural "barrier" is: anything that does not meet what the technical codes or regulations determine to be minimally necessary for accessibility.

For example, a typical ADA legal complaint on a parking stall slope will have boilerplate that looks like this excerpt:
"Plaintiff went to the Business on or about (insert date) for the dual purpose of purchasing a beverage and to verify whether Defendants were complying with the ADA and the UCRA [Unruh Civil Right Act, in California]. At that time, instead of having architectural barrier free facilities for patrons with disabilities, Defendants' facility had barriers that include but are not limited to:
a. an accessible parking area whose slope exceeds ADAAG specification (section 502.4)"

 

[ADAguy]

Thank you for this Yikes.

"Ambulance chasing" law firms and their specialist clients.
1. ADAAG is an incorrect ref for recently (post 2019 sites) it should be 2010 ADASAD for new construction.
2. slope deviations not exceeding 1/2" using a min. 2' - 4' smart level and a 12' straight edge; that are blended as opposed to meeting in vertical faces would seem to not be a barrier to WC users as they are not readily visible and rollable.

The courts are not looking kindly at serial litigants who pursue this manner of approach.

 

[Yikes]

Regarding whether 2% is a "real" barrier:
My guess is that a number of years ago, somebody did a study to see at what slope wheelchairs will start to roll under gravity power alone.
Factors would include friction on the wheel bearings, position of the wheels relative to the direction of slope, etc.
There's probably some concept of being able to position the chair without it rolling away partway through the transfer process.
then it went to a committee to make a recommendation.
1/4" per foot (1:48) is a nice round number that correlates to slopes that roofers know are a minimum for positive drainage when there might also be valleys/swales, and it happens to be close to a percentage number (2%), which is handy for civil engineers. So a compromise was struck, a vote was made, and everyone went out to enjoy a nice lunch.

 

[ADAguy]

interesting point Yikes, what is the tipping angle limit for a WC with all wheels on the ground?