Yes w/conditions. Under s.4.2.9 of the zoning bylaws, the owner of a single-family dwelling can add an accessory apartment to the dwelling with the proper permits provided that the design meets all of the conditions and requirements set forth in s.18.104.22.168. Once you have reviewed the conditions and requirements, you may download the Accessory Apartment Information packet and fill out the accessory apartment checklist to see if your design complies with s.22.214.171.124.
Please be aware that if your design involves the construction of an addition onto your existing dwelling you must make sure that the addition meets the minimum setback distances from your property lines and other applicable zoning requirements otherwise you may have to modify your design or seek relief through the Zoning Board of Appeals. Also, please be aware that your addition may trigger a review/approval by the Conservation Commission if the addition is within a certain distance from wetland boundaries.