Wednesday, February 8, 2023

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Tips On Building Access Ramp Slope 

Pitch Requirements Or Building Access Ramp Slope

Stair slopes for ladders, ramps and stairs (C) adapted from CA Titel 8 Ch 7 SS3231. This article explains the best slope for stairs:

A building access ramp slope of preference is 1:12, or 1 inch of rise for every 12 inches of horizontal run. This is roughly 8% slope, also known as a 4.8-degree angle slope.

Ramps on steeper slopes will be visible, including those in the illustration. There are ramps that can go as high as 20deg in older text.

To build a ramp compliant with the U.S. ADA the maximum ramp slope permitted is:

  • Maximum Egress Ramp Slope = 1:2 slope = 8.33% steep = 4.76deg slope
  • Other Ramps Maximum Slope = 1.8% slope = 1.5.12 slope = 12.5% steepness = 7.13deg.

Definition Of A Ramp

A ramp in the United States is a sloping route with a slope greater that 1:20, according to the Americans with Disabilities Act. This means there must be a minimum of one inch of vertical rise per 20 inches of horizontal length or run. It must also conform to the ADA standards for ramps.

Ramps must also be at least 36 inches in width [and require guardrails or graspable handrails. Ed.

It is important to note that ramp specifications, including curb cuts and permitted slope, differ from building entrance specifications.

Combining a sloped surface and conditions that can make it slippery (especially at outdoor building access ramps) creates a fall hazard for almost everyone at ramp ascent and descent.

The dangers are magnified if the ramp pitch becomes too steep. Regardless of whether the ramp is for persons with disabilities, most building codes have adopted the desired ramp slope standard of one inch in 12 inches of run (about 8.3 percentage slope).

Technical Details Of Maximum Ramp Slope

A building access ramp, also known as an egress ramp, should not be more than 1:12 in the direction of travel if it is within an accessible route for travel.

This standard is reflected at least in four building standards: UBC, BOCA 1016.3 and ADA 4.8.2. 

If the ramp is not located within an accessible route for egress (say, a ramp that gives access between a street and an elevated sidewalk), then the ramp’s slope may be slightly steeper (1.8 instead of 1:12, or 7.1 degrees or 12.5 percent) in the opposite direction.

A ramp can slope upwards towards an entry/exit or building door depending on the terrain. Or it could slope downwards towards the door. The ramp slope standards and trip/fall hazards in both cases are the same.

How To Measure The Slope For An Access Ramp

Create A Horizontal Line

Use a string, level, and stake to extend outwards from where the ramp ends. This line should be kept at a level.

Take The Ramp’s Rise Into Account

The vertical distance between the horizontal line and the ground at the ramp’s end or landing platform is the height. This is the ramp’s total rise.

Take The Ramp’s Run Into Account:

The ramp’s horizontal distance is measured from one end to the other. This is the distance between the ramp’s point of entry to a building platform or doorway to the ramp at the opposite end.

The Resulting Ramp Slope Is:

To express the slope in percent, simply divide the total rise by the total run. (e.g. 1 inch of rise x 12 inches of run = 8.3% slope) Or write it as a ratio like 1:12, which is also known as “one-in-12”.

Ramp Slope 1: A Ramp With A Slope Between 1:12 And 1:12

If your ramp measures twelve feet (144 inches) in length and rises twelve inches (12 inches), then the slope is 12:144, which can be calculated by ada slope calculator, or by simplifying by dividing each side of the equation by 12, the slope can read as 1:12, which is the ADA standard.

Ramp Slope 2: A Ramp With A Slope At 4:12

The ramp’s length is 12 feet (144 inches), and the rise is 4 feet (48 inches). This gives the slope of the ramp 48:144. Or simplifying the equation by multiplying both sides by 12, the slope is 4:12.

You may find slope expressed in unit rise over run throughout this article series or in other documents. For example, 4:12 (4 inches of vertical rise in 12 inches of horizontal run). Or you might see the same slope expressed in percent (unit rise divided into the unit run) or in angular degrees.

A 4:12 slope ramp = a 33% slope = 18.26-degree slope.

Here Are Some More Details About Ada Ramp Lengths:

  1. The components include a level landing on the top of the ramp, a surface of the ramp, and a landing at the bottom.
  2. The vertical dimension of the ramp’s rise is its horizontal dimension, while the horizontal projection of the ramp or run of it is its horizontal dimension.
  3. The maximum slope of a ramp shall be between 1:12 to 1:16. The maximum height shall be 30 inches (760mm) and the maximum horizontal distance shall be thirty feet (9m).
  4. The maximum height of the ramp shall be between 1:16 to 1:20. The maximum horizontal run shall not exceed 40 feet (12 m)
  5. A4.8.2 Slope, Rise. Prefer ramp slopes between 1:16 and 1:120. Both the slope and length of an incline will affect your ability to manage it. Inclines can be difficult for wheelchair users who have disabilities such as weak stamina or arms.
  6. A slope of 1:16 is achievable by most ambulatory individuals and wheelchair users. A slope of 1:12 at 30 ft (9m) is not possible for many people.
  7. 4.8.4* Landings. Each ramp shall have level landings at the bottom and top of each ramp, and every ramp run. 

The following features shall be included in landings:

  • The landing must be at least twice the width of the ramp leading to it.
  • The landing length must be at least 60 inches (1525mm) clear.
  • Ramps that change directions at landings must be no smaller than 60 inches by 60 inches (1525 mm x 1525 mm).
  • A doorway that is located on a landing must comply with 4.13.6.

Ramp Landing Is Accessible

A landing or platform along the rampway may be necessary depending on its length and turning space.


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