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Guide to the ADA Accessibility Standards


This guide provides an introduction to the scoping requirements that form the basis for the Department of Justice’s 2010 ADA Standards and the Department of Transportation's ADA Standards and is not intended to be comprehensive or used as a stand-alone technical guide to those requirements. Users of this guide must familiarize themselves with the specific scoping requirements that apply to each element, building, facility, or site that is subject to the Standards adopted to implement titles II and III of the ADA. See the introduction to the guide on “ADA Scoping: New Construction” for further discussion.

Notational tips for users of screen reading software follow.  In this document ″ indicates inches and ′ indicates feet.  Some images are paired with visually hidden notes.&nbsp These annotations are prefaced with begin and end image notes.



Additions and alterations undertaken at existing facilities are covered by the ADA Standards. The extent of application is largely determined by a project’s scope of work as the standards apply to those elements or spaces that are altered or added. Additional requirements apply to projects that affect or could affect the usability of, or access to, an area containing a primary function.



Projects that increase, expand, or extend a facility’s gross floor area or height of a facility are considered additions (as defined in §106.5) and must comply with the requirements of the standards applicable to new construction. Existing elements and spaces affected by an addition are treated as alterations and qualify for certain allowances or exceptions that are not permitted in new construction.

Application of the Standards in Additions

Existing facility and addition. Figure notes: Existing portions of a facility affected by an addition are treated as alterations. Newly built portions added to an existing facility are treated as new construction. Additions that affect the usability of, or access to, an area containing a primary function must comply with requirements for an accessible path of travel. Unaltered elements and spaces are generally not required to comply (except as needed to provide an accessible path of travel to primary function areas affected by the addition).



Alterations are defined in the standards (§106.5) as “a change in a building or facility that affects or could affect the usability of a building or facility or portion thereof.” Many types of projects are covered as “alterations,” including remodeling, renovation, rehabilitation, reconstruction, restoration, resurfacing of circulation paths or vehicular ways, and changes or rearrangement of structural parts, elements, or walls. Normal maintenance, reroofing, painting or wallpapering, or changes to mechanical and electrical systems are not considered alterations unless they affect a facility’s usability. For example, a project limited to an HVAC system that includes the addition of thermostats would affect a facility’s usability because it involves elements (operable parts) covered by the standards.

The standards ensure that the opportunities for accessibility presented by an alteration are taken. How and to what extent the standards apply is determined by the scope of a project and the elements and spaces altered. Only those elements or spaces altered are required to comply, but alterations made to areas containing a primary function (a major activity for which a facility is intended) also require an accessible path of travel.

Application of the Standards in Alterations

Floor plan with alterations to non-primary function area and to primary function area. Figure notes: Altered elements and spaces are required to comply. In areas not containing a primary function, an accessible route to an altered element or space is required only when the circulation path to the altered element or space is also altered. Alterations made to areas containing a primary function also require an accessible path of travel to the extent that it is not
"disproportionate" to the cost. The accessible path of travel must extend to site arrival points, including parking.

If alterations are limited only to elements in a room or space, then the standards apply only to the elements altered. Similarly, where spaces are altered, the standards apply to those spaces that are altered. If a room or space is completely altered (or built new as part of an alteration), the entire room or space is fully subject to the standards. Compliance is required to the extent that it is technically feasible.

Example: Toilet Room Alterations

Figure of toilet room with altered elements highlighted: toilet, grab bars, faucet controls, and mirror.

In a restroom project involving alterations to the toilet, grab bars, faucet controls, and mirror, the standards apply to these elements but not to those that remain unaltered. In more extensive projects where additional elements are altered, application of the standards is greater, commensurate with the scope of work.

The standards do not require alterations to exceed the level of access required in new construction. For example, spaces that are exempt in new construction are also exempt in alterations.

Prohibited Reduction in Access

New construction requirements also set the baseline for any alteration that would effectively reduce existing accessibility. Alterations that reduce accessibility below the level that would be required in new construction are prohibited. Reductions in access are allowed only where, and to the extent that, the minimum level required in new construction is exceeded. For example, if an alteration will reduce the number of parking spaces on a site, accessible parking spaces can be proportionately reduced as long as the minimum required in new construction (based on the parking facility’s new total) is met. Elements that are not required by the standards to be provided for accessibility, such as phones, can be completely removed from a site.

Special Provisions for Alterations

Page of the standards and magnifying

The standards apply the same requirements used in new construction to alterations but also include provisions unique to alterations. Some provisions clarify application, while others are structured as exceptions that limit coverage or relax technical criteria under certain conditions. Located throughout the standards at the relevant scoping or technical requirement, these provisions and exceptions are distinguished by references to “alterations” or “existing facilities.”

Examples of Provisions for Alterations
escalator symbol
Vertical Access An accessible route to stories and mezzanines is required in alterations (or additions) where stairs or escalators are added where none existed previously and major structural modifications are necessary (§ (or as needed to provide an accessible path of travel to an altered primary function area if not disproportionate to the cost (§202.4)), unless the building is exempt from the requirement for access between stories.
elevator symbol
Elevators If elevators are altered, all cars programmed to respond to the same call control must be similarly modified (§206.6.1).
fire alarm symbol
Fire Alarms Compliant fire alarm systems are required only in alterations where fire alarm systems are installed new, replaced, or upgraded (§215.1, Ex. 1).
ramp symbol
Ramps Slightly steeper running slopes are permitted for short ramps (maximum 6″ rise) where space is limited (§405.2, Ex.).
stair symbol
Stairs Full handrail extensions at stairs are not required where they would project hazardously into circulation paths (§505.10, Ex. 3).

Technical Infeasibility

Compliance in an alteration is not required where it is “technically infeasible.” The term is defined as “something that has little likelihood of being accomplished because existing structural conditions would require removing or altering a load-bearing member that is an essential part of the structural frame; or because other existing physical or site constraints prohibit modification or addition of elements, spaces, or features that are in full and strict compliance with the minimum requirements.”

Where technical infeasibility is encountered, compliance is still required to the maximum extent technically feasible.

Example of Technical Infeasibility

Floor plan shows toilet room constrained in size by corridor./ min. egress width, stair tower, and elevator and freight elevator shafts

It may be technically infeasible in an alteration to enlarge a toilet room confined in size by structural supports, elevator shafts, mechanical rooms and chases, stairways, or required egress routes not affected by the project. In this case, the toilet room must be sized and other requirements, including those for plumbed fixtures, must be met to the maximum extent technically feasible. However, the concept of technical infeasibility remains relative to the planned scope of work. If the entire building is significantly renovated or gutted, constraints of this type would likely not exist.

Other examples where compliance could potentially be technically infeasible include:

  • conflicts with applicable building, plumbing, life safety or other codes (such as when combining two toilet stalls to create an accessible stall would violate the plumbing code’s required fixture count);
  • meeting slope requirements on existing developed sites located on steep terrain where necessary re-grading and other design solutions are not feasible; or
  • work that would impact load-bearing walls and other essential components of the structural frame, including structural reinforcement of the floor slab.

Alterations Affecting Primary Function Areas


Additional requirements apply when alterations are made to areas containing a “primary function,” which is a major activity intended for a facility. Examples of primary function areas include dining areas of a restaurant, retail space in a store, exam rooms in a doctor’s office, classrooms in a school, and offices and other work areas where the activities of a covered entity are carried out. Spaces not considered primary function areas include entrances, corridors, restrooms, break rooms, employee locker rooms, and mechanical or electrical closets. Restrooms are not primary function areas unless their provision is the primary purpose of a facility, such as a highway rest stop. DOJ’s 2010 ADA Standards and DOT’s ADA regulations contain detailed provisions on alterations to primary function areas that must be applied in addition to section 202.4.

Accessible Path of Travel

Symbols: Path of travel, restroom, phone, drinking
fountain When alterations are made to a primary function area, an accessible path of travel to the area must be provided. The accessible path of travel must extend from the altered primary function area to site arrival points, including public sidewalks and parking and passenger loading zones provided on the site. The path of travel also includes access to restrooms, telephones, and drinking fountains, where provided to serve the primary function area. In leased facilities, alterations made by a tenant to primary function areas that only the tenant occupies do not trigger a path of travel obligation upon the landlord with respect to areas of the facility under the landlord’s authority if those areas are not otherwise being altered.

Disproportionality (20%)

The accessible path of travel is required to the extent that it is not “disproportionate” to the total cost. Regulations implementing the standards define “disproportionate” as exceeding 20% of the total cost of alterations to the primary function area. The 20% cap applies only to costs associated with the accessible path of travel, including an accessible route to the primary function area from site arrival points, entrances, and retrofits to restrooms, telephones, and drinking fountains.


The requirements for alterations to primary function areas are found in DOJ's ADA Standards at 28 CFR §35.151(b) (title II) and 28 CFR §36.403 (title III) and in DOT's ADA Regulation at 49 CFR §37.43.

Compliance is required up to the point the 20% cost cap is reached, even where it does not result in a fully accessible path of travel. Where costs exceed this cap, compliance should be prioritized in this order:

  1. an accessible entrance
  2. an accessible route to the primary function area
  3. restroom access
  4. an accessible telephone
  5. an accessible drinking fountain
  6. access to other elements such as parking and storage

Accessible Path of Travel

Plan view: accessible path of travel shown extending from altered
primary function area out of facility to site arrival points (parking,
public sidewalk, and public transit stop). It includes restrooms,
drinking fountains, and telephones serving primary function area. Figure
notes: The accessible path of travel extends from the altered primary
function area to site arrival points (public sidewalks, parking,
passenger loading zones, public transit stops located on the site). The
path of travel also includes an accessible restroom (for each sex unless
only unisex restrooms are provided), telephone, and drinking fountain
serving the primary function area, where such elements are provided.

Alterations to Qualified Historic Facilities


Historic designation plaque: "This property has been placed on the National Register of Historic Places"

The standards contain specific provisions for qualified historic facilities which are defined as buildings or facilities that are “listed in or eligible for listing in the National Register of Historic Places or designated as historic under an appropriate State or local law.” Alterations to qualified historic facilities must comply with section 202.5 to the maximum extent feasible. If it is not feasible to provide physical access to an historic property in a manner that will not threaten or destroy the historic significance of the building or facility, alternative methods of access are permitted by DOJ’s ADA Standards (28 CFR 35.151(b)(3)(ii) and 28 CFR 36.405(b)).

Like other existing facilities, the requirements for alterations apply in relation to the scope of work. Alterations provisions and exceptions, including those based on technical infeasibility, and requirements for path of travel to primary function areas, apply to historic facilities with exceptions for circumstances where compliance with the standards would threaten or destroy the historic integrity or significance of a facility as determined by the appropriate State Historic Preservation Official or Advisory Council on Historic Preservation. These exceptions apply to requirements for accessible routes (§206.2) entrances (§206.4), and toilet rooms (§213.2).

Exceptions for Qualified Historic Facilities (where compliance would threaten or destroy a facility's historic significance) Historic facility. Figure notes: Vertical access to stories above or below the accessible story is not required (§206.2.3, Ex. 7). At least 1 unisex toilet room or 1 men's and 1 women's room is required to comply (§213.2, Ex. 2). At least 1 accessible route is required from a site arrival point to an accessible entrance (§206.2.1, Ex. 1). At least 1 public entrance is required to be accessible (if that would also threaten the historic significance, access can be provided to a non-public entrance but a notification or remote monitoring system is required for locked entrances) (§206.4, Ex.

Common Questions

question mark

What requirements of the standards apply in an alteration?

Application of the standards in an alteration is determined by the scope of work and whether it involves areas containing a primary function. Altered elements or spaces must comply with relevant provisions of the standards except where compliance is technically infeasible. Where compliance is technically infeasible, compliance is required to the maximum extent feasible. If alterations are made to an area containing a primary function (a major activity for which a facility is intended), an accessible path of travel from the area to site arrival points, as well as the restrooms, telephones, and drinking fountains serving the area, must be made accessible as part of the work to the extent it is not “disproportionate” (more than 20% of the total cost).

How is “technical infeasibility” determined in an alteration?

Determining “technical infeasibility” requires a site-specific assessment of constraints or complications in relation to the planned scope of work. The term, as defined in the standards (§106), is intended to encompass design, site, engineering or other constraints that prohibit compliance. Examples include work that would impact a facility’s structural frame or that would conflict with applicable codes or building requirements.

Do the ADA Standards apply to existing facilities that are not subject to the alterations requirements?

DOJ’s ADA regulations address access to existing facilities that are not being altered. The regulations require removal of barriers by public accommodations (title III) and program access by state and local governments (title II). The 2010 Standards apply when architectural changes are made to facilities in order to comply with the program access requirements of title II of the ADA. In addition, the 2010 Standards are the benchmark for compliance with the title III barrier removal requirements. For more information about barrier removal and program access, visit DOJ’s website at or contact the DOJ ADA Information Line at (800) 514-0301 (voice) or (800) 514-0383 (TTY).

Technical Assistance

Contact the Access Board for guidance on these standards