Option A & Option B Bathroom Layouts: Clearing up the Confusion

Let’s first clarify the biggest misconception, Option A and Option B bathrooms are not referencing Type A and Type B dwelling units found in multifamily housing despite the use of a similar naming terminology. It's common for most people to confuse Option A with Type A or think Option B bathrooms are Type B units, but that's not the case.

Option A and B bathrooms are in reference to the two bathroom layouts permitted in Type B covered dwelling units in order to meet the accessibility requirements.

Option A & B bathroom layouts are required in all covered dwelling units found within R-2 residential projects in every city and state across the country. Option A & B bathroom layouts will not apply to hotels or single family homes.

The architect has the choice between these two bathroom layouts when designing Type B units, regardless of the number of bathrooms within the covered dwelling unit. Neither the building code nor the accessibility code have scoping language requiring one bathroom layout be provided over the other. The code citations in this discussion will be referencing ICC ANSI A117.1-2009.

With the Option A bathroom layout, every fixture in every bathroom within the dwelling unit must meet accessibility requirements (except when the bathing fixture is located on a floor level not required to be accessible i.e. multistory dwelling units). ANSI 2009, Section 1004.11.3.1

The code does not limit this requirement to only one bathing fixture per bathroom, even when there are multiple bathing fixtures in the bathroom. If there is a shower and a bathtub or even multiples of the same type of fixture, they will all have to be accessible for Option A compliance.

Option A bathrooms are typically chosen when there are concerns about space efficiency since they have a smaller footprint when compared to Option B; as they allow the lavatory, toilet, and the bathtub to share a common plumbing wall.

This is also the easiest way to identify an Option A layout compared to an Option B, since there will typically only be enough clearance for a forward approach to the tub. The forward approach is a 30” wide by 48” long clearance provided adjacent to the head wall of the tub.

ANSI 2009, Section 1004.11.3.1.3.2

Only one lavatory, toilet, and bathing fixture must meet the requirements, even if there are multiple bathing fixtures in that bathroom. All other bathrooms in the unit (informally referred to as “No Option” bathrooms) will not need accessible fixtures or clearances, but they still need to meet the following:

– Grab bar reinforcing installed in the walls at toilet and bathing fixtures

– Be on an accessible route

– 31 3/4” min clear door opening width

– Switches and outlets within an accessible reach range

While the majority of the technical requirements for Option B are similar to Option A, there are two distinct requirements to be aware of.

Section 1004.11.3.2.1.1, requiring the lavatory to be 34” max AFF measured to the rim or countertop whichever is higher off the floor. 

Section 1004.11.3.2.3.1, requiring a parallel approach at the tub. The parallel approach is a 30” wide by 48” long clearance extending perpendicular from the control wall of the tub.

Answering this question strictly from a construction perspective (not from a design perspective), I would recommend having one of the bathrooms in the dwelling unit designed as an Option B layout.

By choosing an Option B layout only one bathroom in the unit needs to comply with the accessibility requirements. Option A on the other hand means having multiple bathrooms and plumbing fixtures that need to meet the requirements, increasing the odds for something to go wrong during construction.

Feel free to reach out if you have any questions or comments about your bathroom design. We have experience working on multifamily housing across the country both alterations and new construction, and would be more than happy to help you.