Type B Residential Dwelling Unit Bathrooms
by Jimmy Zuehl
Understanding what references establish your regional requirements is the most important part of accessible design. Unfortunately, it can be confusing for designers since there are so many references available.
It would be very difficult to address every standard and every local building code in one article. For the purpose of this newsletter the two standards that are most applicable for Type B residential dwelling unit bathrooms will be addressed: The Fair Housing Act Design Manual (FHADM) and the 2003 ICC/ANSI A117.1 (ANSI). Following these two documents will almost always result in a compliant and accessible bathroom design.
The Fair Housing Act requires accessibility in any new multifamily residential building first occupied after March 13, 1991 and containing four or more dwelling units. The definition of a dwelling unit is any facility used as a residence for more than a brief period of time, including condominiums, apartment houses, townhouses, vacation timeshare units, dormitories, continuing care facilities, and retirement facilities. The design requirements are found in the Fair Housing Act Design Manual (FHADM), probably the most important set of requirements for residential designers. It is most important because it is required at the national level. This means that no matter what jurisdiction (state, county, city, town, or village), most residential projects are also required to meet those standard set by the guidelines.
The second document is the 2003 ICC/ANSI A117.1 standard. Since most all states and many cities develop their own set of building code requirements, the ANSI standard is typically the one document referenced by individual building codes for accessibility. ANSI covers three types of dwelling units: Accessible Units, Type A Units, and Type B Units. Each local building code will require a unit type typically based on the dwelling unit occupancy. And each unit type has its own set of requirements for bathroom design. Accessible Units are most noted as being constructed with all accessible features in place. While Type A Units and Type B Units, on the other hand, are considered “adaptable” and some accessibility features are not required at the time of initial construction. The 2003 ANSI standard has updated its requirements for the Type B Unit to meet the FHADM requirements. Thus the Type B Unit being discussed in this article is sometimes called the Fair Housing Unit.
Now that we have covered the references important to accessible design, it is time to look at the actual building blocks of a residential Type B dwelling unit bathroom. Both the FHADM and ANSI provide two options for bathroom design. FHADM provides a Specification A bathroom and a Specification B bathroom, while ANSI provides an Option A bathroom and an Option B bathroom. When a residential unit has more than one bathroom, designers can either provide all Specification A/Option A bathrooms or one (1) Specification B/Option B bathroom. The Specification B/Option B bathroom has greater access to fixtures and therefore is considered more restrictive and often larger in size. Typically, architects and designers don’t initially see the benefit of providing one bathroom with greater access. However, when one (1) Specification B/Option B bathroom is used, the remainders of all bathrooms within the unit have very few requirements that need to be satisfied. FHADM exempts additional bathrooms from maneuvering clearances at fixtures while the ANSI is even more liberal having no requirements for those additional toilet rooms.
Specification A/Option A
A Specification A/Option A bathroom is made up of three (3) fixtures: the lavatory, the water closet, and the bathing fixture. Each fixture has an associated clear floor space requirement. Both the water closet and the bathing fixture also have required reinforcements in the wall for the future installation of grab bars. Often fixtures also have location requirements that determine where a plumbing element must be located adjacent to other fixtures or walls.
Lavatory Fixture (ANSI 1004.11.3.1.1 and FHADM page 7.47)
Specification A/Option A lavatories are required to have a clear floor space that is 30 inches by 48 inches. This clear floor space must be positioned on the lavatory to allow for either a parallel or forward approach. Both clear floor spaces for the parallel or forward approaches must be centered on the fixture for compliance. Prototype Bathroom 1 and Prototype Bathroom 2 below show the clear floor space for a forward approach. Generally using a forward approach will save a few inches in the overall bathroom design. However when using this approach, the counter and lavatory must be wall hung, allowing a wheelchair to pull under the element. Cabinetry is permitted under the lavatory when using a forward approach provided the cabinetry is removable without the removal or the replacement of the lavatory. The floor finish must also extend under the cabinet. Anytime lavatory pluming is exposed it must be protected. The rim of the lavatory must be no higher than 34 inches above the finish floor.
Water Closet Fixture (ANSI 1004.11.3.1.2 and FHADM page 7.40)
Water closets in Specification A/Option A bathrooms must be provided with one (1) of three (3) allowed approaches to the fixture: a parallel approach, a forward approach, or a parallel and forward approach combination. Each approach has a required clear floor space that is located from the rear wall of the water closet and from a point 18 inches from the centerline of the fixture. Prototype Bathroom 1 below is showing a parallel approach which requires a 56 inch deep by 49 inch wide clear floor space. Both the parallel approach and the forward approach do allow for a wall hung counter and lavatory to obstruct the clear floor space as shown. Both FHADM and ANSI do specify that any fixture obstructing the clears floor space at the water closet must be positioned minimum 15 inches from the centerline of the water closet. However 18 inches is recommended since many local building codes are more restrictive in this instance. Preparation for the future installation of grab bars is required and reinforcing must be provided. See ANSI 1004.11.2 and FHADM page 6.1 for reinforcement requirements.
Bathing Fixture (ANSI 1004.11.3.1.3 and FHADM page 7.53)
While this article does not address shower compartments, we will examine the tub or tub/shower combination fixture. A Specification A/Option A bathroom requires a 30 inch minimum deep by 60 inch minimum in length clear floor space at the tub or tub/shower combination fixture. Both FHADM and ANSI do allow this clear floor space to be obstructed by either a toilet or a wall hung counter and lavatory as shown below in Prototype Bathroom 1. This obstruction is only allowed at the control end of the bathing fixture. Preparation for the future installation of grab bars is also required. Reinforcing must be provided for their future installation. See ANSI 1004.11.2 and FHADM page 6.1 for reinforcement requirements.
Door and Door Maneuvering (See ANSI 404 and FHADM page 3.1)
Contrary to popular belief, doors can swing into the bathroom and even onto the required clear floor space of bathroom fixtures. Only when a “parking space”, or a 30 inch by 48 inch unobstructed area beyond the swing of the door, cannot be provided is it necessary to swing the door outward. Doorways intended for a user to pass through are required to provide 32 inches clear opening width measured between the door stop and the face of the door open at a 90 degree angle. It should be noted that ANSI allows only 31–¾ inch opening width, however FHADM is more restrictive in this instance, requiring the 32 inches. While a 2 foot 10 inch door can provided a user with the required clear opening, a 36 inch door is highly recommended to insure compliance. Also noted in Prototype Bathroom 1 and Prototype Bathroom 2, are the required maneuvering clearances at the doors. ANSI Figure 404.2.3.1 shows required maneuvering clearances for every possible approach and door swing. Remember that these maneuvering clearance are required at both the inside and the outside of the door. A hallway adjacent to the bathroom is required to be wide enough to accommodate all applicable maneuvering clearances. As well, fixtures like the water closet can not obstruct the maneuvering clearance on the inside of the room. Special attention should also be given to the location of bathroom doors in relation to required future grab bars and grab bar reinforcement for fixtures. Prototype Bathroom 2 shows how the change in the door location can change the overall design based on required maneuvering clearances and required grab bar reinforcement.
Specification B/Option B
A Specification B/Option B bathroom, like the Specification A/Option A bathroom, is also made up of three (3) fixtures: the lavatory, the water closet, and the bathing fixture. While the requirements for the lavatory and the water closet are the same in both specifications/options, the requirements at the bathing fixture are much more restrictive in the Specification B/Option B bathroom. This typically results in a slightly larger room design to accommodate the additional requirement.
Lavatory Fixture (ANSI 1004.11.3.2.1 and FHADM page 7.47)
Specification B/Option B lavatories are required to have a floor space that is 30 inches by 48 inches clear and positioned on the lavatory to allow for either a parallel or forward approach. All clear floor spaces for the lavatory must be centered on the fixture for compliance. Prototype Bathroom 3 below shows the clear floor space for a forward approach. Cabinetry is permitted under the lavatory with the same furniture requirements as described in Specification A/Option A. The rim of the lavatory must be no higher than 34 inches above the finish floor.
Water Closet Fixture (ANSI 1004.11.3.2.2 and FHADM page 7.40)
Water closets in Specification B/Option B bathrooms must be provided with one (1) of the three (3) same approaches required in the A options: a parallel approach, a forward approach, or a parallel and forward approach combination. As in the Specification A/Option A bathroom design, both the parallel approach and the forward approach allow for a wall hung counter and lavatory to obstruct the clear floor space. Remember that both FHADM and ANSI specify that any fixture obstructing the clears floor space at the water closet must be positioned minimum 15 inches from the centerline of the water closet, however 18 inches is recommended. Preparation for the future installation of grab bars is also required. Reinforcing must be provided. See ANSI 1004.11.2 and FHADM page 6.1 for reinforcement requirements.
Bathing Fixture (ANSI 1004.11.3.2.3 and FHADM page 7.53)
The most significant difference between the A type bathrooms and the B type bathrooms is the access to the bathing fixture. Specification B/Option B bathrooms are required to have a 30 inch by 48 inch unobstructed clear floor space positioned at the control end of the fixture. Both FHADM and ANSI do not allow this clear floor space to be obstructed by any fixture or any object as shown in Prototype Bathroom 3. Once more preparation for the future installation of grab bars is also required. Reinforcing must be provided. See ANSI 1004.11.2 and FHADM page 6.1 for reinforcement requirements.
Door and Door Maneuvering (See ANSI 404 and FHADM page 3.1)
Door can swing into Specification B/Option B bathrooms and onto the required clear floor space of bathroom fixtures when the 30 inch by 48 inch “parking space” is provided beyond the swing of the door. Doorways intended for a user to pass through are required to provide 32 inches clear opening width. Maneuvering clearances at the doors is required as shown in ANSI Figure 404.2.3.1.
Make sure you review your local building codes before proceeding with any prototype bathroom design. Additional requirements, such as cover tub control requirements, outlets, switches, and medicine cabinets, can be found in the Fair Housing Act Design Manual and the 2003 ICC/ANSI A117.1.