Type ‘A’ vs. Type ‘B’ in Residential Design

Type A dwelling units are those that are required by and defined in the International Building Code. These units are referenced in Chapter 11 of the IBC and have to comprise at least 2% of the units in R-2 occupancies so long as there is more than 20 units. The requirements are specifically called out in Chapter 10 of the ANSI code.

Frequently a multi-unit project will have 1, 2 and 3 bedroom configurations. So when providing 2% Type A units it is required to spread those out among the different types. These requirements are separate from FHA requirements. Those are commonly referred to as Type B units.

A Type B unit in the IBC is essentially equivalent to the Fair Housing Act (FHA) guidelines to accessible units. These units are also often referred to as ‘adaptable’ because they have features that are considered adaptable, such as removable base cabinets and blocking for future grab bars.

Basic Type A features:

  • Turning radiuses
  • Lower shelving
  • Lever type door hardware
  • Accessible threshold throughout
  • Lower kitchen workstations and lavatories

Basic Type B features:

  • Parallel approach at sinks and bathroom vanities
  • Removable base cabinets
  • Blocking for future grab bars

There is a complex web of interaction between building codes and federal and state laws that need to be taken into account when designing most and multi-family project whether it be a standard apartment complex in Colorado or a transit oriented development with a residential component in Canada.


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2 thoughts on “Type ‘A’ vs. Type ‘B’ in Residential Design”

  1. Hi,
    Do you happen to know what is required specifically for the interior of multi family apartments when a person wants to use ANSI type “b” option “b” units for the “ANSI B units being built in a project?

  2. “So when providing 2% Type A units it is required to spread those out among the different types.”

    Could you provide a citation for the requirement to spread accessible units across the unit types? I can’t seem to find that requirement in ICC A117.1, the Fair Housing Design Manual, IBC, or ADA.

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