Do I need a permit to replace it? A job-by-job list for Somerville and Massachusetts
Do I need a permit to replace my roof, windows, water heater or deck boards? A job-by-job permit list for Somerville and Massachusetts homeowners.
Mateus MagnoLicensed Construction Supervisor · October 20, 2026 · 4 min read
In Somerville, almost always yes. ISD requires a building permit for interior and exterior work except painting, tiling and flooring, so roofs, windows, siding, steps, decks and basement finishing all need one, and a water heater swap needs a plumbing permit (plus a gas permit for gas units) pulled by a licensed plumber or gas fitter. Fences don't need a building permit under the zoning ordinance, and small sheds can be exempt under the state code.
"Do I need a permit to replace this?" is the question I hear most on walkthroughs in Somerville, Cambridge and Medford. In Somerville the honest answer is usually yes. The City's rule is broad, the state code's list of exemptions is short, and plumbing, gas and electrical work always go through a licensed trade.
Below is the quick-reference list I give my clients, job by job, with the official source for each answer. When I couldn't confirm something in writing, I say so: check with ISD.
Do I need a permit to replace it? The Somerville rule
Somerville's ISD Building Division says a building permit is required for all interior and exterior work except painting, tiling and flooring, and it must be issued before work starts. Applications go through CitizenServe.
The state code agrees. The Massachusetts Residential Code (780 CMR 51, section R105) makes it unlawful to build, alter, repair or demolish without a permit, then lists a handful of exemptions. "Ordinary repairs" need no permit, but the code says a permit is required to cut away walls, cut structural members, or change a required means of egress.
Job-by-job permit table
| Job | Permit? | Why, and who pulls it |
|---|---|---|
| Replace my roof | Yes (building) | Not on the state exemption list, and Somerville requires permits for exterior work. Roofers can hold a state specialty roof-covering CSL. |
| Replace windows or siding | Yes (building) | Exterior work. The state has a specialty CSL for windows, doors and siding. |
| Replace my water heater | Yes (plumbing; gas too if gas-fired) | The state plumbing board says a permit is needed before plumbing is installed, removed or replaced, and only licensed plumbers can get one. |
| Replace deck boards | Usually yes | A few boards swapped in kind may count as an ordinary repair. A full resurface, or any joist, ledger, post or railing work: file. Unsure? Check with ISD. |
| Replace front steps | Yes (building) | Stairs are part of the means of egress, which the code carves out of "ordinary repairs." |
| Build a fence | No building permit | Somerville zoning says fences don't need one, but height and placement rules still apply (see below). |
| Build a shed | Maybe not | The state exempts one-story detached sheds up to 200 sq ft. Zoning limits still apply. Confirm with ISD. |
| Finish a basement | Yes (building, electrical, plumbing if a bath) | New framing, wiring and often egress changes. Not on any exemption list. |
| Cabinets, countertops, paint, tile, flooring | No building permit | The state lists painting, papering, tiling, carpeting, cabinets and countertops as exempt finish work. Wiring or plumbing changes still need their own permits. |
Water heaters, wiring and gas: always a licensed trade
The Board of State Examiners of Plumbers and Gas Fitters (the board behind 248 CMR) is clear:
- Fixing a leaky faucet or clearing a clog needs no permit.
- Replacing a faucet, valve, fixture or piping is not a minor repair, so it needs a permit.
- Permits are issued only to licensed plumbers; gas work goes to licensed plumbers or gas fitters.
Somerville also requires that a licensed electrician pull every electrical permit. Even a "simple" basement finish usually means three permits.
Fences and sheds: zoning still applies
The Somerville Zoning Ordinance, Article 10 sets the rules:
- Fences: up to 4 feet tall and no more than 50% opaque in the front (frontage) area; up to 6 feet behind it. A fence right on a shared side or rear line needs your neighbor's consent, and the finished face goes outward.
- Sheds: up to 12 feet tall. Accessory structures can sit in side or rear setbacks if they stay at least 3 feet from the lot line, and can't go in the front setback.
The state's 200 sq ft shed exemption comes from the residential code, which covers one- and two-family homes. On a triple-decker lot, ask ISD before you assume anything.
One- and two-family vs. triple-deckers
- Owners of a one- or two-family home they live in may pull their own building permit in Somerville.
- For a three-family or larger, a licensed contractor has to apply.
- For exterior work in a Local Historic District, the Historic Preservation Commission asks for a review through CitizenServe first. More in my historic districts guide.
How to check before you start
- Write down exactly what you're replacing and whether anything structural, electrical or plumbing is touched.
- Look it up in the table above, then confirm on the ISD page or by calling 617-625-6600 ext. 5600.
- Emergency? The state code lets the repair happen first, but the permit application is due the next working business day.
- Read my Somerville building permit guide for the full application steps.
Need a hand?
I pull permits across Somerville and Greater Boston every week, from Davis Square condos to triple-deckers in East Somerville. Book a free walkthrough and I'll tell you which permits your job needs and send a written line-item budget, usually within 48 hours.
Frequently asked questions
Do I need a permit to replace my roof in Massachusetts?
Yes, in Somerville and generally across Massachusetts. Re-roofing isn't on the state code's exemption list, and Somerville ISD requires a building permit for exterior work.
Do I need a permit to replace my water heater?
Yes. Massachusetts requires a plumbing permit before plumbing is replaced, and a gas permit for gas-fired units. Only licensed plumbers or gas fitters can get them.
Do I need a permit to build a fence in Somerville?
No building permit is needed under the Somerville Zoning Ordinance, but fences are limited to 4 feet in the front area and 6 feet behind it.
Do I need a permit to finish a basement?
Yes. Finishing a basement involves new framing and wiring, so expect a building permit plus an electrical permit, and a plumbing permit if you add a bathroom.
Mateus Magno is the founder of Magno & Co — a licensed Massachusetts Construction Supervisor (CS-123658), registered Home Improvement Contractor (HIC #220484) and certified Lead-Safe Renovator Supervisor who has renovated and managed over $3 million in projects across Greater Boston.
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