Massachusetts

Carports and garages in Massachusetts almost always need a building permit from your local building department, under one statewide code called 780 CMR. Your local building department enforces it, and your town's zoning bylaw decides where a building can go on your lot. On a home lot, a one-story storage shed up to 200 square feet is exempt from a building permit. Farms get strong zoning protection under state law, but farm buildings still go through the building permit process.

Building code in effect

Massachusetts builds to the 10th Edition of the Massachusetts State Building Code (780 CMR), based on modified versions of the 2021 International Codes, including the 2021 IRC and 2021 IBC. It first took effect October 11, 2024, and after a concurrency period with the 9th Edition, it became the only building code in effect on July 1, 2025. Homes and their accessory buildings fall under the residential code, 780 CMR 51.00. The state board (BBRS) is now working on an 11th Edition built on the 2024 IRC, with subcommittee meetings still going on in fall 2026, but it had not taken effect as of October 2026.

Who issues permits

Building permits are issued by the building commissioner or inspector of buildings in your city or town, under M.G.L. c. 143. Counties have no role in building permits. The state building inspector only handles buildings owned by the Commonwealth. Zoning is a separate local review under your town's zoning bylaw, and it controls setbacks, height and where an accessory building can sit. Some towns also require conservation commission review near wetlands.

County permit guides

• Barnstable County
• Berkshire County

Don't see your county? Call 919-725-8176 and we'll help you find the right office.

When you need a permit

• Small sheds: Under 780 CMR 51.00 R105.2, a one-story detached accessory structure used as a tool or storage shed is exempt from a building permit if the floor area is not more than 200 square feet.
• Carports and garages: A carport or garage is not a tool and storage shed, so plan on a building permit no matter the size. Your building department will check the foundation, anchoring and design loads.
• Commercial buildings: Outside the residential code, the 780 CMR amendment to section 105.2 exempts sheds only up to 120 square feet.
• Plastic greenhouses: Greenhouses covered only with plastic film are exempt from a building permit under 780 CMR 105.2, as long as they are not used for large gatherings of people.
• Electrical work: Lights, outlets or a subpanel need an electrical permit from your town's wiring inspector, even when the building itself is exempt.

Farm buildings

Massachusetts does not exempt farm buildings from building permits. What 780 CMR 107.6.1 does is exempt buildings used only for agriculture from construction control (the extra supervision by a registered design professional required on larger projects), with limits found in Appendix C for Group U agricultural buildings. Zoning is where farms get real protection. Under M.G.L. c. 40A, s. 3, a town cannot prohibit, unreasonably regulate or require a special permit for commercial agriculture, or for building structures on that land, on parcels of 5 acres or more (or 2 acres or more with at least $1,000 per acre in gross sales). Electrical work in any farm building still needs a permit.

Wind and snow

Weather in Massachusetts changes a lot from one end to the other. Cape Cod, the Islands and the South Coast face hurricanes and nor'easters with some of the highest design wind speeds in New England. The Berkshires and the hill towns of central and western Massachusetts get much heavier snow. Ask your local building department for the design wind speed and ground snow load for your town before you order. Our partnered manufacturers offer certified buildings rated for 140 MPH wind and 35 PSF snow load, and higher ratings can be quoted where required.

Before you order

• Call your town's building department first. The permit comes from the building commissioner or inspector of buildings, not the county.
• Check your zoning bylaw for accessory building setbacks and height, and ask if the conservation commission needs to review work near wetlands.
• If you farm 5 acres or more, ask the town how it applies the agricultural protection in M.G.L. c. 40A, s. 3. You will still need a building permit.
• Get the design wind speed and ground snow load for your town, especially on the Cape or in the Berkshires.

Common questions

Do I need a permit for a carport in Massachusetts?
Yes, in most cases. The residential code (780 CMR 51.00, R105.2) only exempts one-story tool and storage sheds up to 200 square feet. A carport is not a storage shed, so get a building permit from your city or town building department.

Do I need a permit for a metal garage in Massachusetts?
Yes. A metal garage needs a building permit under the 10th Edition of 780 CMR, based on the 2021 IRC. Your town will also check zoning, and any wiring needs an electrical permit.

Are farm buildings exempt?
Not from the building permit. Buildings used only for agriculture are exempt from construction control under 780 CMR 107.6.1, and M.G.L. c. 40A, s. 3 limits how towns can use zoning against farms on qualifying parcels. Plastic film greenhouses are exempt from a building permit.

Sources

• Mass.gov: Tenth edition of the MA State Building Code 780
• Mass.gov: 780 CMR 51.00 Massachusetts Residential Code, Chapter 1 (10th Edition)
• Mass.gov: 780 CMR 10th Edition, Chapter 1 Scope and Administration amendments
• Massachusetts Legislature: M.G.L. c. 40A, s. 3
• Mass.gov: BBRS 11th Edition Residential Code Subcommittee Meeting, 10/1/26

Permit rules change. Always confirm with your local permit office before you build.

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