Hello PA testers! During a recent Virtual Workshop hosted by @coachfaithbroussard, we received the following question: do we need to memorize the 2% slope rule, or just understand the intent?
What Is It?
The 2% slope rule refers to accessibility standards like the Americans with Disabilities Act (ADA), and determines when a surface is classified as a ramp vs. sloped walkway.
Why Is It Important?
A 2% slope allowance exists because in real-world construction, achieving a perfectly flat surface is nearly impossible. Thus, sloped surfaces up to 2% are considered “level.” Slight slopes are often needed for drainage, so accessibility guidelines tolerate up to a 2% slope without triggering additional requirements.
When a walkway’s slope is greater than 2% (1:50), it is no longer considered a level surface, and classified as an accessible route instead. If the running slope in the direction of travel meets or exceeds 5% (1:20), the walkway must adhere to all ramp requirements, including handrails, edge protection, landings, and a maximum length per rise. Thus, the 2% rule ensures that accessible routes are both usable and safe for users.
In summary, slopes 2% (1:50) and under are treated as level surfaces. Slopes between 2-5% are classified as accessible routes. Slopes 5% (1:20) and greater are ramps, and trigger stricter requirements. As an ARE candidate, it’s important to understand the 2% slope rule and its real-world applications before heading into the exam.
If you have any other questions about the 2% slope rule, let us know down in the comments!
Ryan Rendano, Assoc. AIA, LEED GA
Architect 3D Model Designer
Black Spectacles