Weymouth's Accessory Structures: The Rules That Matter

Every city handles accessory structures a little differently. In Weymouth, Massachusetts, there are 2 distinct rules that residents and property owners should be aware of. Some are stricter than what neighboring cities enforce, and others are more relaxed. Here is what you need to know.

ADU Rules

Weymouth Town Council passed ADU Ordinance Amendment (Measure 24-119) adding Article 29 to Chapter 120. ADUs are allowed by right on single-family lots up to 900 sq ft or 50% GFA. Lots under 5,000 sq ft are ineligible.

Key details: Code Section: Weymouth Code Ch. 120, Art. 29 (Measure 24-119). Max Size (small lots): 750 sq ft (lots under 25,000 sq ft). Max Size (large lots): 900 sq ft (lots over 25,000 sq ft). Ineligible Lots: Under 5,000 sq ft. Parking: 1 space (waived within 0.5 mi of transit).

Non-compliant ADUs subject to zoning enforcement.

Weymouth is more permissive than most cities when it comes to adu rules. That said, there are still limits.

Garage Conversions

Garage conversions to ADUs in Weymouth are permitted under the 2025 ADU ordinance (Article 29). Conversions require a building permit, Site Plan Approval, and design review. The converted ADU must comply with the 750–900 sq ft size limit and setback requirements.

Key details: Permitted?: Yes: under ADU Article 29. Max Size: 750–900 sq ft depending on lot size. Permits Required: Building permit + Site Plan Approval + design review. Building Dept.: (781) 335-2000.

Unpermitted conversions subject to stop-work orders and zoning enforcement.

The Bottom Line

Weymouth's accessory structures rules are a mixed bag. Some areas are strict, others are relaxed, and the details matter. The best approach is to check the specific rule that applies to your situation rather than assuming Weymouth is broadly strict or permissive.

This guide is based on Weymouth's current municipal code. Local rules can and do change, so check the individual ordinance pages for the latest details, penalties, and FAQs.