How Many ADA Units Are Required in Apartment Buildings?

There is no single number of ADA units required in apartment buildings. Federal law doesn’t set one figure, and “ADA units” is shorthand people use for rules that actually come from three different statutes. The Fair Housing Act requires every covered unit in qualifying multifamily buildings built for first occupancy after March 13, 1991 to include adaptable design features. Section 504 of the Rehabilitation Act requires 5% of units in federally funded projects to be fully accessible for mobility disabilities, plus another 2% for hearing or vision disabilities. The ADA itself generally doesn’t reach individual apartments at all; it covers the public-facing spaces like leasing offices and clubhouses.

Which number applies to your building depends on when it was built, whether it takes federal money, and which spaces you’re asking about.

The Fair Housing Act Covers Every Qualifying Unit, Not a Percentage

This is where the biggest misconception sits. The FHA does not say “make 5% of your units accessible.” It says every covered unit must be designed and constructed with specific adaptable features.¹

The law reaches multifamily buildings with four or more units designed and constructed for first occupancy after March 13, 1991. That includes condominiums, townhouses, garden apartments, and dormitories.² In a building with an elevator, every unit is covered. In a walk-up without an elevator, only ground-floor units must comply. So in a 200-unit elevator building, all 200 units need the FHA features. In a 200-unit walk-up, only the ground-floor units do.

“Adaptable” is doing important work here. A covered unit doesn’t need to look like a hospital room on move-in day. It needs bones that a resident with a disability can adjust without tearing out walls: reinforcement behind bathroom drywall for grab bars, doorways wide enough for a wheelchair, a kitchen that a wheelchair user can maneuver through.

What Counts as the Ground Floor

In buildings without elevators, identifying the ground floor isn’t always obvious. If the floor at grade level is entirely parking, retail, or common areas with no apartments, the first floor above or below that contains dwelling units becomes the designated ground floor for FHA purposes.³ Split-level floors that don’t add up to a full story are treated as one ground floor rather than two.

Multistory Townhouses

A townhouse with living space spread across two or more floors and no internal elevator is not covered by the FHA’s design and construction requirements, even if the entrance sits at ground level. The rule can’t demand an accessible route through a unit when stairs are the only way between floors. Single-story townhouses at grade level are covered like any other ground-floor unit.

The 5% and 2% Rules for Federally Funded Buildings

Section 504 of the Rehabilitation Act is the only federal law that mandates a specific percentage of fully accessible units, and it applies only when the housing receives federal financial assistance, such as HUD-funded developments or projects financed with certain tax credits.

For new construction of five or more units, at least 5% of the total (or a minimum of one, whichever is greater) must be fully accessible for people with mobility impairments. An additional 2% (again, at least one) must be accessible for people with hearing or vision impairments.⁴

For a 100-unit federally funded development the math looks like this:

Mobility-accessible units: 100 × 5% = 5 units
Hearing or vision-accessible units: 100 × 2% = 2 units
Total fully accessible: 7 units

These Section 504 units must meet the Uniform Federal Accessibility Standards (UFAS) or an equivalent standard. That bar sits higher than the FHA’s adaptable design features. A UFAS-compliant unit includes finished features like roll-in showers, lowered countertops, and visual alarm systems for hearing-impaired residents, not just the structural bones that allow later modification.

Section 504 stacks on top of the FHA. The remaining 93 units in that 100-unit example still have to meet the FHA’s adaptable design standards. Developers sometimes treat the 5% as their only obligation and miss this.

What the Required Features Actually Look Like

The FHA spells out seven categories of design requirements for every covered unit. Missing them is treated as housing discrimination under federal law.¹

An accessible building entrance connected to public streets and sidewalks without steps or other barriers.
Accessible common areas, so lobbies, mailrooms, and laundry rooms are reachable and usable.
Doors wide enough for wheelchairs, both into and within the unit.
An accessible route through the unit, maintaining at least 36 inches of clear width, with exterior door thresholds no higher than ¾ inch.⁵
Environmental controls (light switches, outlets, thermostats) placed between 15 and 48 inches from the floor where there are no obstructions, so a seated person can reach them.⁶
Reinforced walls around toilets, tubs, and showers to support grab bars a resident may install later.
Usable kitchens and bathrooms, with a 30-by-48-inch clear floor space at each appliance and fixture and at least 40 inches of clearance between opposing base cabinets, countertops, and walls.⁷

Common Areas and Parking Have Their Own Counts

Accessibility requirements don’t stop at the apartment door. All common areas available to residents must be on an accessible route and usable by people with disabilities: lobbies, laundry rooms, fitness centers, pools, community rooms, trash disposal areas, and mailbox areas.⁸

For parking, the FHA requires a minimum of 2% of parking spaces serving covered dwelling units to be accessible and located on an accessible route. In a complex with 150 resident spaces, that means at least 3 accessible spaces. If the development offers different types of parking (surface lots, garages, covered carports), at least one accessible space must appear in each type, even if that pushes the total above 2%.⁸

For any public-facing areas governed by the ADA, such as a leasing office, the ADA’s own parking table applies separately, on a sliding scale by total spaces. A lot with 1 to 25 total spaces needs 1 accessible space; a lot with 26 to 50 needs 2.⁹

Older Buildings

The FHA’s design and construction requirements apply only to buildings designed for first occupancy after March 13, 1991. Older buildings aren’t retroactively required to redesign. They aren’t off the hook entirely, though.

Under the ADA, existing facilities with public-facing spaces have an ongoing duty to remove architectural barriers when doing so is “readily achievable,” meaning the work can be done without significant difficulty or expense. What qualifies depends on the cost of the work relative to the operator’s financial resources, the nature of the operation, and technical feasibility. It isn’t a one-time assessment; as finances change, work that was once too expensive can become readily achievable.

Individual Tenant Requests

Beyond construction standards, every housing provider, regardless of when the building was built, has to respond to individual tenant requests. Federal law separates two types, and the distinction determines who pays.

A reasonable accommodation is a change to a rule, policy, or practice. Allowing a service animal in a no-pets building, assigning a closer parking space, or permitting a live-in aide in a unit with single-occupancy restrictions all count. The housing provider covers the cost.¹⁰

A reasonable modification is a physical change to the unit or common area: installing grab bars, widening a doorway, building an entrance ramp. Under the FHA, the tenant pays. In federally funded housing covered by Section 504, the housing provider must cover the cost of structural changes unless doing so would create an undue financial burden.¹⁰

When a tenant requests either, the housing provider can ask for verification of the disability-related need, but only the minimum information necessary. A letter from a healthcare provider confirming the person has a disability and needs the requested change is enough. The landlord cannot ask for a specific diagnosis, treatment details, or medical records.¹¹ If the disability is obvious, such as a wheelchair user requesting a ramp, the provider generally cannot request verification at all.

What Getting It Wrong Costs

For Fair Housing Act violations, someone who believes they’ve been discriminated against can file a complaint with HUD within one year of the last discriminatory act.¹² If HUD finds reasonable cause and the case reaches an administrative hearing, an administrative law judge can impose civil penalties that scale with history:

No prior violations: up to $26,262 per discriminatory practice
One prior violation within 5 years: up to $65,653
Two or more prior violations within 7 years: up to $131,308

¹³

An individual can also bypass HUD and file a federal lawsuit within two years of the discriminatory act. Courts can award compensatory damages, punitive damages, and attorney’s fees with no statutory cap, so large-scale design and construction cases against developers can result in settlements or judgments well into the millions.¹⁴

For ADA Title III violations involving public-facing areas of apartment complexes, the Department of Justice can seek civil penalties of up to $75,000 for a first violation and $150,000 for subsequent violations, with periodic inflation adjustments that may push current figures higher. Private individuals can also file ADA lawsuits seeking injunctive relief plus attorney’s fees.

Design and construction cases are among the most expensive types of housing litigation because the fix often means retrofitting entire buildings. Developers who cut corners during construction routinely face remediation costs that dwarf what compliance would have cost in the first place.

1
Office of the Law Revision Counsel. 42 USC 3604 – Discrimination in the Sale or Rental of Housing
2
U.S. Department of Housing and Urban Development. Fair Housing Act Design Manual
3
U.S. Department of Housing and Urban Development. Fair Housing Act Design Manual – Chapter 1
4
eCFR. 24 CFR 8.22 – New Construction Housing Facilities
5
U.S. Department of Housing and Urban Development. Fair Housing Act Design Manual – Chapter 4 Accessible Route Into and Through the Covered Unit
6
U.S. Department of Housing and Urban Development. Fair Housing Act Design Manual – Chapter 5 Environmental Controls
7
U.S. Department of Housing and Urban Development. Fair Housing Act Design Manual – Chapter 7 Usable Kitchens and Bathrooms
8
U.S. Department of Housing and Urban Development. Fair Housing Act Design Manual – Chapter 2
9
United States Access Board. Guide to the ADA Accessibility Standards – Chapter 5 Parking Spaces
10
U.S. Department of Housing and Urban Development. Joint Statement on Reasonable Modifications
11
U.S. Department of Housing and Urban Development. Appendix 6-B Verification of Disability
12
U.S. Department of Housing and Urban Development. Learn About FHEO’s Process to Report and Investigate
13
eCFR. 24 CFR 180.671 – Assessing Civil Penalties for Fair Housing Act Cases
14
Office of the Law Revision Counsel. 42 USC 3613 – Enforcement by Private Persons