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This document provides building code specifications, sketches, photographs, and examples of defects used in inspecting indoor or outdoor building access ramps and related conditions for slip and fall hazards, general safety and proper construction. Our page top photo shows a new entry ramp added to a building. The step at the ramp entry reduced the ramp slope to less than 1:12 but it created an obstruction for wheelchair users. Below we also discuss the best methods to improve the safety at an improperly sloped or slippery building access ramp.

For a complete list of articles on stairs, railings, and ramps, their inspection, trip hazards, and good design, see STAIRS, RAILINGS, LANDINGS, RAMPS - INSPECTIONS, CODES. Also see Building Safety Hazards Guide. Here we include references to key documents on building codes and stair and railing safety.

© Copyright 2009 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

Basic Building Access Ramp Specifications & Safety Defects

Here we discuss and illustrate the requirements for safe, useable interior and exterior access ramps in buildings. 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.

Building Access Ramp Slope or Pitch

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.

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: UBC 1003.3.4.3, BOCA 1016.3, ADA 4.8.2, 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.

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.

Measuring the slope of a ramp is simple:

1. 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.
2. 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.
3. 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.
4. 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).

An Explanation of Building Access Ramp Slip and Fall Hazards

Slips, Trips, Missteps and Their Consequences, by Bakken et als. provides clear and well-thought out explanations of how and why people slip and fall on stairs, walks, and ramps. Section 20.2 in Bakken et als. discusses ramp design specs and falls on ramps. The following quotes are from that text:

Principal Causes of Ramp Falls:

Most ramp falls are related to the ramp being too steep or slippery. Such conditions are often exacerbated when the ramp is wet or accumulated debris is present. -- op cit p. 199:

People sometimes tend to move faster when walking downward on ramps due tithe increased forward momentum created by the slope. Therefore ramps should have even greater slip-resistant surfaces than level walking surfaces, such as sidewalks, which are typically in the range of 0.65 SCOF. While a pedestrian can more easily judge her or his slower and more deliberate speed on a staircase, it is sometimes more difficult to realize that one is increasing speed when descending an unfamiliar ramp, hence a propensity to forward-moving falls while descending ramps. -- op cit.

Static Coefficient of Friction - How Slippery is the Slope of Your Ramp?

In the cited text and other engineering references, SCOF is the static coefficient of friction. Page 23 in the above text gives the SCOF requirements for slopes of various inclines. A 1 in 12 slope, which is an 8.3 percent slope (the recommended pitch by most sources) is bracketed by SCOFs for two slopes: a 0.93 SCOF for a 9.3 percent slope, and SCOF of 0.625 for a 6.25 percent slope.

Visual Clues Affect the Chances of Falling on a Ramp

A pedestrian's perception of the walking surface is critical in the causality of slip incidents. If a person perceives a "reasonably safe" walking surface, one which provides a reasonable level of slip resistance, he or she will adjust her gait accordingly on the basis of this contemporaneous tactile and/or visual input. If a person's perception is not augmented by other internal or external warning stimuli, and if the person encounters a portion of the walking surface at heel strike that provides a SCOF below the traction demand, a slip will most probably occur.-- op cit.

In other words, using an improper and ineffective "anti slip" coating (such as ordinary paint) might actually increase the risk of falling not only for being a potentially surprise slip surface itself, but also because the presence of such a coating provides a visual clue that would be expected to lead a pedestrian to think that the surface had *extra* slip resistance when in fact it does not. Be certain that any anti-slip paints or add-on non-slip tread materials used on a ramp are intended for that use.

The text also includes material on ramp railings (that can be a visual clue about ramp height, slope, and dangers), and on other ramp markings as they also affect ramp safety.

How Do We Make A Slippery, Dangerous Access Ramp Safer?

Remove slippery materials: clean algae or other slippery materials from the surface - if necessary using deck cleaner and a power washer. Where possible, correct the underlying conditions that cause algae or other debris collection on a ramp surface - sometimes simply by cutting back overhanging tree branches, the added sunlight will reduce algae growth as well as frost or ice formation.

Improve ramp surface traction: for a ramp that will be used for both wheelchairs and walking pedestrians, install anti-slip tread materials or use an anti-slip paint; be sure that you select outdoor-rated materials if the ramp is outside. For a ramp that is used only by walkers (no wheelchairs) some builders install cleats, typically 16" o.c. across the ramp but in our opinion, the cleats can themselves form a trip hazard and may violate building codes. Instead, if the ramp is so steep that you are considering cleats, fix the ramp slope, as we discuss below.

Correct a slippery, too-steep building access ramp by extending its length and thus reducing the pitch or slope, OR by lifting the low-end of the ramp up, building a step up at its entry end so that the ramp slope itself is reduced to a safe degree, in both cases combined with the steps above. I.e. change the ramp length or lift its low end and add a step up, so as to keep the ramp slope to no more than 1 in 12. But adding a step at the lower end of the ramp, reducing its slope, only works for ramps that do not need to be wheelchair accessible.

Add railings on your ramp: if the ramp crosses above a ditch, ravine, or is more than three feet from the ground at its highest point, a railing is likely to be required by local and national building codes. Even for ramps that are just a few inches above the ground, railings improve ramp safety by providing additional visual clues about the ramp's slope as well as providing a grasping surface in case of a fall. Our photo (left) shows the author's daughter (at left, ca. 1979) with a friend, demonstrating that this building access ramp was unsafe: a railing was provided only on one side despite the drop off, and the railing that the carpenters installed was both open (a child hazard), and used a horizontal mid-height member, easily climbed-on by a child (another child hazard).

Landing platforms for ramps: Make sure the ramp is properly designed in width, structural support, and that it includes a landing both at the upper end at a building entry/exit door, and where required by local code or ground surface conditions, also provide a landing platform at the ramp's lower end. As we mentioned at our page to photo, the step at this building access ramp entry reduced the ramp slope to less than 1:12 but it created an obstruction for wheelchair users. While the landing platform assists the users of this access ramp, what we had specified was that the ramp bottom end terminate at grade, without a step. The "railings" along this ramp are not readily graspable, but as the ramp is nearly level, we considered them as a balcony railing not a handrail.

Place ramp boards right-side up: it's a bit more subtle, but during ramp construction, if the ramp surface is constructed of 2x lumber (such as pressure treated 2x6 boards, a common choice for outside building ramps), look at the ends of each board before it is nailed in place, and flip the board so that the "bark side" will be facing upwards - to better drain. If you click to enlarge the photo at left you might notice that the two most-rotted deck boards (photo center) were installed "upside down" with the end grain cupped upwards or "concave"; you can also plainly see the end grain in the two 3x12's forming the deck girder (photo lower center). You'll see by the wood end grain pattern tha the girder right-hand board has it's "bark side" facing right, and the left hand board has its "bark side" facing left. Cupped ramp boards (or deck and platform boards) hold water and form algae or ice more quickly than boards that drain properly. They sometimes rot faster too, as we show in our photograph. Look at the end-grain of any deck, ramp, or wooden walkway board and notice the curved lines that mark the winter wood layers of the tree from which the board was cut. If these lines arch "upwards" when the board is placed, most boards will also be curved upwards (convex) and will drain better. But before nailing a deck or ramp board in place, look at the board surface itself - sometimes the boards don't follow these "cupping rules".

Building Access Ramp Standards and Codes

• 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)
• Access Ramp building codes:
  • UBC 1003.3.4.3
  • BOCA 1016.3
  • ADA 4.8.2
  • IBC 1010.2

A Comparison of Building Codes Specifying Hand Railing Requirements That May Also Apply To Access Ramps      

Railings in stair codes and specifications refer to the safety barrier along ramps as well as at steps or stairs, landings, and balconies. Also see Guards for details about safety railings on landings and open hallways, porches, screened porches, balconies - horizontal walking surfaces. Sample excerpts of sources which a building code compliance inspector would be expected to cite in support of requiring a properly-designed, properly-secured guard rail include but are not limited to the citations below.

International Building Code 2000 (BOCA, ICBO, SBCCI)

1003.3.3.11.3 Handrail grasp ability. Handrails with a circular cross section shall have an outside diameter of at least 1.25 inches (32 mm) and not greater than 2 inches (51 mm) or shall provide equivalent grasp ability. If the handrail is not circular, it shall have a perimeter dimension of at least 4 inches (102 mm) and not greater than 6.25 inches (159 mm) with a maximum cross-section dimension of 2.25 inches (57 mm). Edges shall have a minimum radius of 0.125 inch (3.2 mm).

100333.11.4 Continuity. Handrail-gripping surfaces shall be continuous, without interruption by newel posts or other obstructions.

1607.7 Loads on Handrails, guards, grab bars and vehicle barriers

1607.7.1.1 Concentrated Load. Handrail assemblies and guards shall be able to resist a single concentrated load of 200 pounds (0.89kN), applied in any direction at any point along the top, and have attachment devices and supporting structure to transfer this loading to appropriate structural elements of the building.

1607.7.1.2 Components. Intermediate rails (all those except the handrail), balusters and panel fillers shall be designed to withstand a horizontally applied normal load of 50 pounds (0.22 kN) on an area not to exceed one square foot (305mm2) including openings and space between rails.

BOCA National Property Maintenance Code 1993:

PM-305.5 Stairs and railings: all interior stairs and railings shall be maintained in sound condition and good repair.

Commentary: Handrails, treads and risers must be structurally sound, firmly attached to the structure, and properly maintained to perform their intended function safely. During an inspection the code official should inspect all stringers, risers, treads, and handrails.

PM-305.6 Handrails and guards: Every handrail and guard shall be firmly fastened and capable of supporting normally imposed loads and shall be maintained in good condition.

Commentary: This section provides for the safety and maintenance of handrails and guards. See Section PM-702.9 for additional requirements.

PM-702.9 Stairways, handrails and guards: Every exterior and interior flight of stairs having more than four risers, and every open portion of a stair, landing or balcony which is more than 30 inches (762mm) high, nor more than 42 inches (1067mm) high, measured vertically above the nosing of the tread or above the finished floor of the landing or walking surfaces. Guards shall be not less than 30 inches (762mm) high above the floor of the landing or balcony.

Commentary: Handrails are required on all stairs more than four risers in height. Handrails cannot be less than 30 inches nor more than 42 inches above the nosing of the treads (see Figure PM-702.9).

Guards are required on the open side of stairs and on landings and balconies which are more than 30 inches above the floor or grade below. The guard must be at least 30 inches above the floor of the landing or balcony. Guards are to contain intermediate rails, balusters or other construction to reduce the chance of an adult or child from falling through the guard. If the guard is missing some intermediate rails or balustrades, it is recommended that the guard be repaired to its original condition if it will provide protection equivalent to the protection it provided when originally constructed.

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Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

• Our recommended books about building design, inspection, and repair, and about indoor environment testing, diagnosis, and cleanup are at the InspectAPedia Bookstore.
• "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:
  • UBC 1003.3.4.3
  • BOCA 1016.3
  • ADA 4.8.2
  • IBC 1010.2
• 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 sales@lawyersandjudges.com 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.
• The following stair books and other books on stair history, design, and architecture can be purchased at our Amazon-Supported InspectAPedia Bookstore
• Steps and Stairways, Cleo Baldon & Ib Melchior, Rizzoli, 1989.
• The Staircase: History and Theories, John Templar, MIT Press 1995
• The Staircase (two volumes), John Templar, Cambridge: the MIT Press, 1992.
• "The Dimensions of Stairs", J. M. Fitch et al., Scientific American, October 1974.
• ...

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