Code of Massachusetts Regulations
974 CMR - DEVENS ENTERPRISE COMMISSION
Title 974 CMR 5.00 - Residential
Section 5.05 - Accessory Apartments

Accessory apartments are permitted in single family dwellings. Accessory apartments may be located in the same structure as the principal dwelling or in combination with space for a permitted home occupation or business, a garage, or other allowed accessory use, or as a separate structure itself, provided that the total gross square feet of the accessory apartment, whether within the same structure or a separate one, is limited to 25% of the floor area of the principal dwelling. Dwellings with accessory apartments shall retain the appearance of single-family dwellings. An accessory apartment within the dwelling is a Level One permit, an accessory apartment in a detached structure is a Level Two permit.