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California Building Code Excerpt

Section 11B-302 Floor or Ground Surfaces

Code excerpt regarding technical requirements for floor or ground surfaces: general, carpet, and openings.

11B-302 Floor or ground surfaces

11B-302.1 General. Floor and ground surfaces shall be stable, firm, and slip resistant and shall comply with Section 11B-302.


  1. Within animal containment areas, floor and ground surfaces shall not be required to be stable, firm, and slip resistant.
  2. Areas of sport activity shall not be required to comply with Section 11B-302.

Advisory 11B-302.1 General. A stable surface is one that remains unchanged by contaminants or applied force, so that when the contaminant or force is removed, the surface returns to its original condition. A firm surface resists deformation by either indentations or particles moving on its surface. A slip-resistant surface provides sufficient frictional counterforce to the forces exerted in walking to permit safe ambulation.

Advisory 11B-302.1 General. Outdoor walking surfaces are often constructed of concrete or asphalt. Where permeable surfaces such as compacted decomposed granite or similar material are part of the accessible route, stabilizing admixtures or binders can help to provide a firm, stable and slip-resistant surface. Such surfaces should be edged or otherwise contained to provide stability. The maintenance required to keep these surfaces firm and stable should be considered when selecting such materials.  Additional information regarding accessible exterior surfaces is available on the US Access Board website at

11B-302.2 Carpet. Carpet or carpet tile shall be securely attached and shall have a firm cushion, pad, or backing or no cushion or pad. Carpet or carpet tile shall have a level loop, textured loop, level cut pile, or level cut/uncut pile texture. Pile height shall be 1/2 inch (12.7 mm) maximum. Exposed edges of carpet shall be fastened to floor surfaces and shall have trim on the entire length of the exposed edge. Carpet edge trim shall comply with Section 11B-303.

Advisory 11B-302.2 Carpet. Carpet and permanently affixed mats can significantly increase the amount of force (roll resistance) needed to propel a wheelchair over a surface. The firmer the carpeting and backing, the lower the roll resistance. A pile thickness up to 1/2 inch (13 mm) (measured to the backing, cushion, or pad) is allowed, although a lower pile provides easier wheelchair maneuvering. If a backing, cushion or pad is used, it must be firm. Preferably, carpet pad should not be used because the soft padding increases roll resistance.

Advisory 11B-302.2 Carpet. The accessibility provisions of the California Building Code apply only to the design, alteration, and new construction of buildings and facilities, not to movable floor mats. However, if floor mats are built-in as part of new construction or alterations, and are part of an accessible route, they must comply with the accessibility provisions of this section and Section 11B-302.1 which requires firm, stable and slip-resistant surfaces along accessible routes.  However, in addition to circumstances in which the California Building Code applies to built-in floor mats, there may also be circumstances in which Americans with Disabilities Act (ADA) requirements apply to floor mats that are not built in. If movable floor mats impede access for people with disabilities, they may need to be moved or removed under Section 36.304 of the ADA Title III regulations. That section requires that a public accommodation remove barriers in existing facilities where removing them is “readily achievable,” that is, easily accomplishable and able to be carried out without much difficulty or expense. Even though the requirements of this chapter would not apply to the mats themselves, the ADA regulations can provide helpful guidance in ensuring that mats do not constitute barriers.

Figure 11B-302.2 Carpet Pile Height
Figure 11B-302.2 Carpet Pile Height

11B-302.3 Openings. Openings in floor or ground surfaces shall not allow passage of a sphere more than 1/2 inch (12.7 mm) diameter except as allowed in Sections 11B-407.4.3, 11B-409.4.3, 11B-410.4, 11B-810.5.3 and 11B-810.10. Elongated openings shall be placed so that the long dimension is perpendicular to the dominant direction of travel.

Figure 11B-302.3 Elongated Openings in Floor or Ground Surfaces
Figure 11B-302.3 Elongated Openings in Floor or Ground Surfaces

Advisory 11B-302.3 Openings. Elongated openings, like those of most grates, must be oriented so that the long dimension is perpendicular to the dominant travel direction. In locations where there is no dominant flow pattern, openings should be limited to 1/2″ in both dimensions. Where an accessible route is available to bypass openings completely, they can be oriented in any direction.

Gray area interpretation: Openings that measure less than 1/4″ in at least one direction are not opening barriers, even if associated with a larger dimension in another direction that would otherwise be described as an elongated opening. Rationale: The widely understood intent of regulating elongated openings is to prevent entrapment of wheeled mobility devices. Published mobility device manufacturer or industry data for wheel dimensions and capabilities is inconsistent or missing altogether, so an empirical study is not readily achievable. However, if we consider that 1/2″ is the maximum horizontal opening dimension allowed to avoid creating an impassable hazard for wheels, then we can relate that to the 1/2″ maximum height of a change in level to avoid creating an insurmountable hazard for wheels. Following this line of logic, if 1/4″ is the maximum vertical dimension capable of being rolled over, then it should follow that a vertical dimension less than 1/4″ does not present unusual difficulty to roll over. Therefore, by association, a horizontal opening less than 1/4″ should not present unusual difficulty to roll over. And so at least one opening dimension must be less than 1/4″ to avoid being considered an (elongated) opening.