Massachusetts Building Permit Guides

Massachusetts runs one statewide code and enforces it town by town. The Massachusetts State Building Code, 780 CMR, is written by the Board of Building Regulations and Standards and applies in every city and town. Towns cannot rewrite it; the main local difference is the energy code, because many towns have opted into the state’s stretch or specialized energy code. There is no county building code: each city or town enforces the state code, though some small towns share an inspector. The 10th edition took effect on October 11, 2024, ran concurrently with the 9th until June 30, 2025, and has been the only code in force since July 1, 2025. It is built on the 2021 International Codes — building, residential, existing building, mechanical, energy, swimming pool and fire — with Massachusetts amendments substantial enough that the model text alone will mislead. The residential provisions sit in Chapter 51, which adopts the 2021 IRC as amended.

The code draws the exemption line, and it is the same line everywhere in the Commonwealth. Ordinary repairs need no permit; anything that constructs, reconstructs, alters, repairs, removes or demolishes a building, or changes its use or occupancy, needs one from the building official. Electrical work runs under the Massachusetts Electrical Code, 527 CMR 12. Plumbing and gas work run under the Uniform State Plumbing Code and the Massachusetts Fuel Gas Code, both in 248 CMR. The city or town’s own wiring, plumbing and gas inspectors issue and inspect those permits, not the building inspector.

Massachusetts issues no general contractor licence. It issues two separate credentials that cannot stand in for each other, and permit work on an existing home often needs both, though not always from the same person. The Construction Supervisor Licence, under M.G.L. c. 143 and 780 CMR, is an examined licence issued by the Board of Building Regulations and Standards through the Office of Public Safety and Inspections, and held by the individual supervising the work. It comes in three forms: unrestricted, for buildings of any use under 35,000 cubic feet; restricted, for one- and two-family homes; or one of the specialty classes, such as roofing, windows and siding, or insulation. Larger buildings are overseen by a registered architect or engineer instead. Home Improvement Contractor registration, under M.G.L. c. 142A, is a consumer-protection registration with the Office of Consumer Affairs and Business Regulation, required of anyone contracting work on an existing owner-occupied home of one to four units, with a written contract required above $1,000 and access to the state Guaranty Fund behind it. A homeowner may take out the permit on their own one- or two-family home under the supervisor licence exemption by signing the affidavit — but doing so gives up the Guaranty Fund protection a registered contractor’s permit would carry. Electricians, plumbers and gas fitters hold their own state licences, and the wiring and plumbing inspectors issue trade permits only to licence holders.

The trades are permitted separately from the building permit and inspected by the town's own wiring and plumbing inspectors, under the state codes and licences rather than any local one.

A Massachusetts building permit application is filed with the building official, who reviews the construction documents. Under 780 CMR 105.3.1 the official must issue or deny the permit in writing within 30 days of filing, and must give written reasons for any denial.