What Is an ADA Unit? Accessible, Type A and Type B Units Explained

By Erik Tishenko, Modern Northwest · Published November 4, 2026

"ADA unit" usually means an apartment built for a wheelchair user, but in most apartment buildings it is the wrong name. The Americans with Disabilities Act covers places open to the public, so in an apartment complex it reaches the leasing office and other public areas, not the homes. The apartments are covered by the federal Fair Housing Act and by the building code, which sort units into four levels: Accessible, Type A, Type B and Type C. Here is what each one means and when a building needs it, from the builder's side.

From the ICC A117.1 accessibility standard that the building code references, and the Fair Housing Act rules. Most apartment units in a new building are Type B.

Planning an apartment building, fourplex or mixed-use project? We build multifamily in Portland and Southwest Washington. See our multifamily construction work, or call (360) 326-2747.

Why "ADA unit" is usually the wrong name

The ADA is a civil rights law for public accommodations: hotels, restaurants, stores, offices that serve the public. Apartments are housing, and housing has its own federal law, the Fair Housing Act. So a market-rate apartment building does not have "ADA units." What it has are units built to the Fair Housing Act design rules, which the building code calls Type B, and in larger buildings some Type A units too.

The ADA does still reach an apartment property in the places the public uses. The leasing office, a community room rented out for events and the parking that serves them follow the ADA rules. That is why the same project can have an ADA-compliant leasing office and Type B apartments a few feet away.

The Fair Housing Act design rules

The Fair Housing Act design rules apply to buildings with four or more units first occupied after March 13, 1991. In a building with an elevator, every unit is covered. In a building without one, the ground-floor units are covered. Townhomes where each home has its own stairs, with no elevator, are generally outside these rules.

The covered units have to be adaptable, not fully accessible. The federal rule lists seven requirements:

• An accessible building entrance on an accessible route.
• Accessible public and common-use areas.
• Doors wide enough for a wheelchair.
• An accessible route into and through each unit.
• Light switches, outlets and thermostats within reach.
• Reinforced bathroom walls so grab bars can go in later.
• Kitchens and bathrooms a wheelchair user can maneuver in.

Notice what is not on the list: grab bars, lowered counters, roll-in showers. Those are features of a fully accessible unit. A Type B unit is built so they can be added when a tenant needs them, without tearing the unit apart.

Type A units: the building code's extra layer

The building code goes one step past the federal law. In apartment buildings with more than 20 units, at least 2 percent of the units have to be Type A, spread across the unit types instead of grouped together. A Type A unit has the full door and route requirements of an accessible unit, with some features left adaptable, like cabinets that can be removed under a sink for a front approach or blocking for grab bars.

Oregon and Washington both build their state codes on the International Building Code, which is where these Type A and Type B rules come from. Oregon's current commercial code, the 2025 Oregon Structural Specialty Code, is based on the 2024 International Building Code. Our Oregon and Washington pages cover which code edition applies on each side of the river.

What it means for an owner building now

The count of units and whether the building has an elevator decide most of the answer. A few examples from buildings we have built in Portland:

• A fourplex. Our 4,045 square foot 73rd fourplex sits right at the four-unit line where the Fair Housing rules begin. Four units in one building is enough.
• A building under 20 units. The 55th Apartments has 16 units: over the Fair Housing threshold, but under the 20-unit line where the building code starts requiring Type A units.
• An elevator building. 2425 NE Alberta is a four-story mixed-use building with an elevator. With an elevator, the Fair Housing rules reach every unit, not just the ground floor. Our mixed-use construction guide covers how the shops below and the homes above follow different rules.

Why it has to be designed in, not fixed later

The building department reviews and inspects to the building code. The Fair Housing Act is a federal civil rights law, and plan review does not enforce it. A building can pass every inspection and still have a Fair Housing problem that no one finds until a resident files a complaint. Fixing door widths, bathroom clearances or a route after people live in the building costs far more than drawing them right the first time. The unit types belong in the first layout with the architect, when moving a wall is still a pencil change.

Frequently asked questions

The bottom line

Apartments do not have ADA units. They have Type B units under the Fair Housing Act, and buildings over 20 units also need Type A units under the building code. The ADA covers the leasing office and other public areas. Count the units, check for an elevator, and design the unit types in from the start.

Modern Northwest has built commercial and multifamily projects across Portland and Southwest Washington since 2005, licensed in Oregon (CCB #198582) and registered in Washington (L&I MODERNI888R7). Tell us about your building and we will walk through what it needs.