This bill amends the existing zoning ordinances in Chapter 45-24 of the General Laws to include new provisions regarding the construction of attached single-family dwellings. It introduces a definition for "attached single-family dwelling" as a dwelling unit constructed side by side or horizontally and separated by a party wall and lot line. The bill mandates that zoning ordinances must allow for the construction of these units in designated zoning districts, as specified in 45-24-37(j).

The bill outlines specific requirements for attached single-family dwellings, including:
- Access to public water and sewer, or adequate access to private water and/or wastewater systems approved by the relevant state agency.
- The ability for each single-family unit to be located on its own lot without increased requirements for minimum lot size, lot width, lot frontage, or lot depth, and allowing for a zero-lot line setback along the common property line.
- Compliance with building and fire codes.
- Other dimensional requirements of the base zoning district shall apply to the outside perimeter property lines of the end-units, with no increased dimensional requirements solely applicable to attached single-family structures compared to other residential structures of the same density in the same zoning district.
- Cities and towns may establish additional standards for such units, provided that these standards do not restrict a dwelling unit's floor area ratio to less than one, limit the number of bedrooms to less than three, or require more than one off-street parking space for up to two bedrooms, and two off-street parking spaces for up to three bedrooms.

The bill emphasizes that all towns and cities must allow attached single-family units in residential districts that permit the construction of two or more units, with the number of attached single-family units allowed corresponding to the residential density for the property and zoning district. The act is set to take effect on January 1, 2026.