521 CMR Residential Building Additions and Unit Accessibility

Are you working on a project that involves the construction of an addition to an existing residential building or an existing building that is being converted to residential use? If so, here is the scoping criteria for unit accessibility per 521 CMR.

An addition is defined by 521 CMR 5.1 as “an extension or increase in floor area or height of a building or structure”. Regardless of the addition (vertical or horizontal), the following provisions apply to all residential additions to existing buildings that consist of 20 or more units that are for rent, hire, lease or sale that were originally constructed prior to September 1, 1996.

Residential Units for Rent, Hire or Lease (Rental Apartments)

  • Group 1 units are not required to be provided in existing buildings, including any addition, as Group 1 requirements are exempt under 521 CMR 9.2.1.
  • Group 2A units are required to be provided in existing apartment buildings in accordance with 521 CMR 9.4. Five percent of the total number of units are required to comply with Group 2A requirements.

Residential Units for Sale (Condominiums)

Neither Group 1 nor Group 2 units are required to be provided in existing condominium buildings, including any building addition as Group 1 & 2 requirements are exempt under 521 CMR 9.2.1 & 9.4 (per the reference “but not for sale”).