Important Factors When Installing Truncated Domes

Detectable warning surfaces are a necessary factor in meeting the ADA 2020 standards for accessible design. Having incorrectly installed truncated domes could result in an ADA lawsuit, so it is important to know what is required to meet compliance standards.


In the past, detectable warning surfaces, also known as truncated domes, were commonly found in red, blue, grey, and yellow. The ADA guidance does not specify a particular color as long as there is a contrast with the surrounding surface. However, state laws do often specify a color. For example, in California, truncated domes should be yellow, specifically standard shade AMS-STD 33538 for maximum visibility. 


Much research has been done into what level of spacing is best for those using a wheelchair, walker, cane, or other mobility aid. As a result, truncated domes must follow precise spacing guidelines between 1.6 and 2.4 inches from center to center of each dome. In addition, the minimum space between the base of each dome must be at least 0.65 inches.

3 - SIZE

It is also essential for each truncated dome to be of a specific size. The base diameter should be a minimum of 0.9 inches and a maximum of 1.4 inches. The height of each of the domes must be 0.2 inches. Truncated domes are arranged in a grid to provide a distinct feeling under food or when a mobility aid makes contact with them.


Truncated domes should be installed on any public right-of-way that merges onto an area that presents a hazard. This includes locations such as curb ramps, crosswalks, reflecting pools, and transit platform edges.


Curb cuts must be 3 feet wide and at least 2 feet from where the pedestrian path transitions into a street or other area with traffic, such as a parking lot. In addition, the bottom of the ramp must have a 24inch warning strip, and the ramp itself must not exceed 8.33 percent.

All of these factors are essential for truncated domes that are both ADA and California code compliant. California Truncated Dome Company can make sure you are fully compliant. Contact us for a compliance analysis today.


Guaranteed to Meet Code & Last!

Our primary focus here at California Truncated Domes Company is handling all of your truncated dome needs. This is what we do. We are experts in this particular area of ADA construction and will make sure your truncated domes are in full compliance with ADA guidelines and the California Access Compliance Manual.

Book your $98 Compliance Analysis Today.