Cambridge MA building permit: a step-by-step guide for homeowners
How to get a Cambridge MA building permit: Inspectional Services, the online portal, fees, historic district review, permit lookups and how long it takes.
Mateus MagnoLicensed Construction Supervisor · October 20, 2026 · 4 min read
In Cambridge, building permits come from Inspectional Services (ISD) and you apply through the City's online permitting portal. The building fee is $15 per $1,000 of construction cost for buildings with three units or fewer ($50 minimum), and ISD issues or denies the permit within 30 days after your fee is paid, once other departments have signed off.
A Cambridge MA building permit is issued by the City's Inspectional Services Department (ISD), and you apply online. Most renovations need one: kitchens, baths, basements, porches, decks, additions and anything that touches structure. Here is the process I follow for my clients in Cambridge, step by step, with the official links.
If you've read my Somerville building permit guide, the idea is the same. Cambridge just adds a few extra stops, especially around historic districts and approvals from other departments.
Who issues a Cambridge MA building permit, and what needs one
According to the City's Apply for a Building Permit page, you need a permit before you construct, alter, repair or demolish a structure, and the permit card must be posted on site. Ordinary repairs, as the Building Code defines them, are exempt.
- Permits are generally issued to licensed construction supervisors.
- Homeowners can pull their own permit only for a one- or two-unit home they live in or plan to live in.
- The City's building permits page says sheds under 120 square feet don't need one, but zoning still applies.
- Electrical, plumbing and gas work need their own permits, pulled by the licensed trades.
Step by step: the Cambridge building permit application
Cambridge runs its applications through an online permitting portal (OpenGov). The steps, per the City:
- Register and log in to the portal. You can save a draft and finish later.
- Fill out the application and upload your documents as PDFs: drawings for the scope, the Affidavit for Estimated Cost of Construction, and the Homeowner's Affidavit if you're pulling it yourself. Forms are on the ISD building permits page.
- Other departments review first. The application goes to non-ISD departments (zoning, the Historical Commission, traffic) and it's on you to get their approvals.
- ISD sends an invoice. Pay online by card or e-check (service fees apply) or by check at the counter. Your application isn't considered received until it's paid.
- ISD reviews and prints the permit card for pickup.
Keep all correspondence inside the portal's Comments section. The City asks for that instead of emailing staff directly.
Building permit fees in Cambridge, MA
These rates come from the ISD Building Fees schedule, based on your construction cost:
| Project | Fee |
|---|---|
| Homes with 3 units or fewer | $15 per $1,000 of cost, $50 minimum |
| All other new construction, repairs, alterations | $20 per $1,000 of cost, $50 minimum |
| Residential certificate of occupancy | $100 first unit, $50 each additional |
So a $60,000 kitchen in a two-family works out to about $900 for the building permit. Start work before the permit is issued and the fee is tripled. At the end, the owner files an Affidavit for Final Cost of Construction, so the number should be honest from day one.
Historic and conservation districts: check before you design
This is where Cambridge differs most from its neighbors. The Cambridge Historical Commission oversees two historic districts (Old Cambridge and Fort Washington) and four neighborhood conservation districts (Mid Cambridge, Half Crown-Marsh, Avon Hill and Harvard Square).
- For work in a district or on a landmark, you need a certificate from the Commission before ISD will issue the building permit.
- Interior work and in-kind repairs usually get a Certificate of Non-Applicability, often issued on the spot by staff.
- Visible exterior changes, like new windows, siding or an addition, may need a hearing.
- Citywide, demolition review covers buildings over 50 years old, and a significant building can be delayed up to twelve months.
Not sure if your house is in a district? Look it up in the MyCambridge tool or call the Commission at 617-349-4683.
How to look up past permits by address
Before I price a job, I check what's been permitted at the house. In April 2026 the City launched the Cambridge Permit Finder, which lets you search by address, permit type, date range and status. For older permits and plans, the ISD record room at 831 Massachusetts Avenue keeps permits, plans and certificates of occupancy.
Inspections and how long it takes
Once your fee is paid, ISD issues or denies the permit within 30 days. If staff have questions, the clock pauses until you answer them. The real wildcard is the earlier step: zoning relief or a historic hearing can add weeks or months.
- Work must start within six months of the permit being issued.
- Expect at least a rough inspection (framing, insulation, trades) and a final inspection.
- Construction hours are 7 a.m. to 6 p.m. on weekdays, 9 a.m. on Saturdays and holidays, with no Sunday work.
Need a hand?
I pull permits for kitchens, baths, porches, additions and ADUs in Cambridge, Somerville and Medford, from drawings to final inspection. Book a free walkthrough and I'll usually send you a written line-item budget, permit plan included, within 48 hours.
Frequently asked questions
How do I apply for a building permit in Cambridge, MA?
Register on the City's online permitting portal, fill out the application and upload your documents as PDFs. Other departments review it first, then Inspectional Services invoices the fee and reviews the permit once it's paid.
How much is a building permit in Cambridge, MA?
For buildings with three units or fewer, the fee is $15 per $1,000 of construction cost with a $50 minimum. Other projects pay $20 per $1,000, and starting work without a permit triples the fee.
How do I look up building permits by address in Cambridge?
Use the City's Cambridge Permit Finder, which searches by address, permit type, date and status. Older permits and plans are kept in the ISD record room at 831 Massachusetts Avenue.
How long does it take to get a building permit in Cambridge?
ISD issues or denies the permit within 30 days after the fee is paid. Approvals from zoning or the Historical Commission come before that and can add time.
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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