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Residential permit rules in Massachusetts

Representative cities: Boston, Worcester. Covers 16 common home projects.

Verify locally. Massachusetts enforces ONE statewide code (780 CMR, 10th Edition, effective Oct 2024, IRC-based) with a licensed Construction Supervisor requirement for most work. Boston and Worcester also adopted the Stretch/Specialized Stretch energy code, which adds insulation and HVAC efficiency rules. Rules below are state/city-level guidance drawn from official sources — always confirm with the issuing building department before starting work. See the county permit authorities to find the right office.

Project	Permit?	Authority	Typical fee	Timeline	Go / No-Go	Key notes
🏠 Accessory Dwelling Unit (ADU)	Permit required	city	Valuation-based; set by the issuing city (Boston uses a long-form permit).	Boston: up to ~5 weeks for long-form permit review; longer with zoning relief.	Generally allowed	Massachusetts requires ADUs by right under MGL c. 40A §3A; Boston requires a long-form building permit and zoning review. Exempt: State law (MGL c. 40A §3A) allows ADUs by right on lots with a single-family home.
🪵 Deck / Porch	Conditional	city	Valuation-based; each city sets its own schedule.	Worcester: ~3–4 weeks; Boston: short-form fast, long-form several weeks.	Generally allowed	A licensed Construction Supervisor (CSL) is required unless the owner does the work on an owner-occupied home. Exempt: Decks ≤200 sq ft, ≤30 in above grade, not attached, not serving a required exit are exempt.
🧱 Fence / Wall	Conditional	city	Often no building permit below the height threshold; zoning relief may apply.	Usually no building-permit review below threshold.	Generally allowed	Disputes over property-line fences are treated as civil matters by many cities. Exempt: Statewide exempt for fences ≤7 ft (780 CMR R105.2).
🛖 Shed / Outbuilding	Conditional	city	Valuation-based when over the size threshold.	Small sheds often exempt; larger sheds need plan review.	Generally allowed	Structures with plumbing, electrical, or gas connections require a permit regardless of size. Exempt: One-story detached sheds/playhouses ≤200 sq ft are exempt (780 CMR R105.2).
🪜 Basement Finish	Permit required	city	Valuation-based; includes trade permits.	Standard plan review 2–4 weeks.	Generally allowed	Boston basements in high water-table zones may require perimeter drains/sump pumps. Exempt: Cosmetic finishing (paint, flooring) is exempt.
🚗 Garage / Carport	Permit required	city	Valuation-based; includes trade permits.	New-structure plan review; varies by city.	Generally allowed	Attached and detached garages require a full building permit and plan review. Exempt: No exemption — a new garage is a new structure.
☀️ Rooftop Solar PV	Permit required	city	Building + electrical permits; fee set by city.	Varies; many municipalities offer streamlined residential PV review.	Generally allowed	Net-metering and state incentives apply; confirm structural capacity with the building department. Exempt: No size exemption for permanent rooftop PV.
🌡️ HVAC Replacement	Permit required	city	Mechanical permit; fee set by city.	Trade permits often issued quickly.	Generally allowed	Equipment must meet the Massachusetts energy/stretch code where adopted. Exempt: No exemption for equipment replacement/installation.
🍳 Kitchen Remodel	Conditional	city	Valuation-based when structural/plumbing/electrical work is included.	Worcester: ~2–3 weeks for full remodels.	Generally allowed	Full remodels pull separate plumbing/electrical sub-permits. Exempt: Cabinet/countertop swap in the same layout is exempt.
🛁 Bathroom Remodel	Conditional	city	Valuation-based when plumbing is relocated.	Standard review for permitted scopes.	Generally allowed	Ventilation to the exterior is required. Exempt: Fixture-for-fixture swap in place is often exempt.
🏗️ Room Addition	Permit required	city	Valuation-based; includes trade permits.	Worcester: 4–8 weeks; Boston zoning review may add time.	Generally allowed	Boston additions may require a Zoning Board of Appeal hearing if beyond the envelope. Exempt: No exemption — any new conditioned footprint requires a permit.
🪟 Window / Door Replacement	Conditional	city	Usually no fee for in-kind swap; permit needed if opening is enlarged.	In-kind swaps typically need no review.	Generally allowed	Replacement products must meet energy/stretch-code U-factor when the code is triggered. Exempt: Same-size, in-kind replacement is generally exempt.
🏘️ Roof Replacement	Conditional	city	Valuation-based; ordinary repairs may be exempt.	Worcester roof replacement plan review usually <1 week.	Generally allowed	Boston requires an asbestos survey for homes built before 1980 before re-roofing. Exempt: Ordinary repairs (no structural change) are exempt; full tear-off/replacement needs a permit.
🅿️ Driveway / Parking Pad	Conditional	city	Building permit often not required; curb-cut/right-of-way work is separate.	Right-of-way permits reviewed by the city/DPW.	Generally allowed	A separate right-of-way permit is usually needed to cut the curb. Exempt: Sidewalks and driveways ≤30 in above grade are exempt (780 CMR R105.2).
🏊 Swimming Pool / Spa	Permit required	city	Valuation-based; includes barrier/fencing and electrical bonding review.	Plan review varies; barrier inspection required.	Generally allowed	Barrier fencing and electrical bonding per code are mandatory for permanent pools. Exempt: Prefabricated pools <24 in deep are exempt (780 CMR R105.2).
🧱 Retaining Wall	Conditional	city	Valuation-based when over the height threshold.	Over-threshold walls need plan review.	Generally allowed	Walls in wetland or steep-slope areas may trigger additional review. Exempt: Walls <4 ft from bottom of footing to top are exempt (780 CMR R105.2).

State-wide sources: Mass.gov — Massachusetts State Building Code (780 CMR) · City of Boston — Inspectional Services Department · City of Worcester — Building & Zoning