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Building access ramp slope, pitch or angle specifications & codes: this document provides building code specifications, sketches, photographs, and examples of defects used in inspecting indoor or outdoor building access ramps.
Bottom line: the preferred slope for a building access ramp is between 7 and 15 degrees, and permitted slopes range between 0 and 20 degrees.
This article series on access ramp design & construction explains and illustrates the requirements for safe, useable interior and exterior access ramps in buildings.
[Click to enlarge any image]
Readers should note that the design specifications for permitted slope and other specifications for ramps that are not used for building entry or exit, such as curb cuts, are different from those used at building entrances.
For example a steeper slope may be permitted on non-access ramps. For complete details about building access ramp construction: slope, width, railings, non-slip surfaces, steps, landings at ramps, etc. See the standards, code, and ADA REFERENCES at the end of this document.
The combination of a sloped surface with conditions that can make that walking surface slippery, especially at outdoor building access ramps, forms a falling hazard at both ramp ascent, and ramp descent for nearly everyone. These hazards are particularly increased if the ramp pitch is too steep. The desirable ramp slope standard, one inch of rise in 12 inches of run (about 8.3 percent slope), has been adopted by most building codes regardless of whether or not the access ramp is specifically for people with disabilities.
Our illustrations above and below describe the recommended slope range for building access ramps, fixed stairs, and other structures.
If a building access ramp (also called an egress ramp) is located within an accessible route of travel and is used as a means of egress (exiting from a building), the ramp slope should be 1:12 (4.8 degrees, 8.3 percent) or less in the direction of travel.
This standard is reflected in at least four building standards:
IBC 1010.2, and is elaborated in an excellent book that we recommend on stairs and ramps, Slips, Trips, Missteps and Their Consequences, by Bakken et als, found in references at the end of this article.
If the ramp is NOT located within an
accessible route of egress (say a ramp giving access between the street and an elevated sidewalk), the slope of the ramp may be
a little steeper (1:8 rather than 1:12, or 7.1 degrees, or 12.5 percent) in the direction of travel.
Incidentally, depending on terrain, a ramp may slope upwards towards a building entry/exit door, or it may slope downwards towards the entry door. In either case, the ramp slope rules and standards are the same and the trip/fall hazards are essentially the same.
How to measure the slope of an access ramp
Project a horizontal line (use a string, level, and stake if it helps) outwards from the uppermost end of the ramp - say the building entry platform - and the end of the ramp. Keep this line dead level.
Measure the Ramp's Rise: Measure the height (the vertical distance) from the horizontal line to the ground surface at the end of the ramp or its landing platform. This is the total rise of the ramp.
Measure the Ramp's Run: Measure the ramp's total horizontal distance from one end of the ramp to the other - say from the point at which the ramp reaches a level building entry platform or entry door to the opposite end of the ramp.
State the Resulting Ramp Slope: Simply write the total rise divided by the total run to express the slope as a percent (1 inch of rise / 12 inches of run = 8.3% slope), or write the slope as a ratio such as 1:12, also expressed as "one in twelve".
Ramp Slope Example 1: if your ramp is twelve feet long (144 inches) and the rise is twelve inches (12 inches) then the slope of the ramp is 12:144, or simplifying, dividing both sides of the equation by 12, the slope can be written as 1:12 - which meets the desired ADA standard.
Ramp Slope Example 2: If the ramp is twelve feet long (144 inches) and the total rise is four feet (48 inches) then the slope of the ramp is 48:144, or simplifying by dividing both sides of the equation by 12, the slope of this ramp is written as 4:12 (and the ramp is too steep, likely to result in a fall).
Access Ramp Landing slope
Separately from the slope of the access ramp walkway itself, in some situations a landing or platform may be required along a rampway, depending on the ramp length and the requirement for turning space.
Also see RAMP LANDING CODES.
Landings shall have a slope not steeper than one unit
vertical in 50 units horizontal (2-percent slope) in any
direction. Changes in level are not permitted. - Florida Building Code 1010.6.1 Landings.
Continue reading at RAMP SLIP TRIP FALL HAZARDS or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.
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"The Elimination of Unsafe Guardrails, a Progress Report," Elliott O. Stephenson, Building Standards, March-April 1993
"Are Functional Handrails Within Our Grasp" Jake Pauls, Building Standards, January-February 1991
Access Ramp building codes:
Access Ramp Standards:
ADA (Americans with Disabilities Act), Public Law 101-336. 7/26/90 is very often cited by other sources for good design of stairs and ramps etc. even where disabled individuals are not the design target.
ANSI A117.4 Accessible and Usable buildings and Facilities (earlier version was incorporated into the ADA)
ASTM F 1637, Standard Practice for Safe Walking Surfaces, (Similar to the above standards)
Slips, Trips, Missteps and Their Consequences, Second Edition, Gary M. Bakken, H. Harvey Cohen,A. S. Hyde, Jon R. Abele, ISBN-13: 978-1-933264-01-1 or
ISBN 10: 1-933264-01-2,
available from the publisher, Lawyers ^ Judges Publishing Company,Inc., www.lawyersandjudges.com firstname.lastname@example.org and also from the InspectAPedia Bookstore (Amazon.com)
The Stairway Manufacturers' Association, (877) 500-5759, provides a pictorial guide to the stair and railing portion of the International Residential Code. [copy on file as http://www.stairways.org/pdf/2006%20Stair%20IRC%20SCREEN.pdf ] -
The following stair books and other books on stair history, design, and architecture can be purchased at our Amazon-Supported InspectAPedia Bookstore
Falls and Related Injuries: Slips, Trips, Missteps, and Their Consequences, Lawyers & Judges Publishing, (June 2002), ISBN-10: 0913875430 ISBN-13: 978-0913875438 "Falls in the home and public places are the second leading cause of unintentional injury deaths in the United States, but are overlooked in most literature. This book is unique in that it is entirely devoted to falls. Of use to primary care physicians, nurses, insurance adjusters, architects, writers of building codes, attorneys, or anyone who cares for the elderly, this book will tell you how, why, and when people will likely fall, what most likely will be injured, and how such injuries come about. "
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