Do I need a permit for a shed in Cambridge, Massachusetts?
A small shed is allowed, but it has to meet zoning at any size. The state building code exempts one-story storage sheds of 200 sq ft or less from a building permit, while the city's FAQ still says 120 sq ft, so check with Inspectional Services for a shed between 120 and 200 sq ft. In the Residence C-1 district, an accessory building can be at most 15 feet tall, must meet the district setbacks (10 ft front, 5 ft side/rear), and all accessory buildings and uses together can cover at most 15% of the lot.
| Building permit threshold (city FAQ) | Not required under 120 sq ft [1] |
| Zoning compliance | Required for any size shed [1] |
| Setback in Residence C-1 | Same minimum setbacks as the district [2] |
| Residence C-1 minimum setbacks (residential uses) | 10 ft front, 5 ft side/rear [3] |
| Max height (Residence C-1) | 15 feet [4] |
| Max lot coverage of accessory uses/buildings | 15% of the lot (excluding parking and driveways) [5] |
| Required yards | Must stay open; sheds aren't among the allowed yard features [6] |
| Floodplain Overlay District | Permit from the Floodplain Administrator required for sheds [8] |
Do you need a permit?
The Inspectional Services Department's FAQ says a building permit isn't required for a shed under 120 square feet, but any shed, whatever its size, must comply with the Zoning Ordinance [1]. The state building code, which applies statewide, exempts one-story storage sheds of 200 sq ft or less from a building permit (see the state rules section). The city FAQ's 120 sq ft figure appears to be older than that threshold, so the state rule may apply instead. Confirm with ISD before skipping a permit for a shed between 120 and 200 sq ft.
Where it can go
In Residence C-1 districts, an accessory building can't be closer to any lot line than the district's minimum setback [2]. Table 5-1's Residence C-1 row (shown in [3] as the raw table cells) sets a 10-foot minimum front yard and a 5-foot minimum side or rear yard for residential uses; the numbers in parentheses are footnotes, such as the rule letting a house match its neighbors' average front setback. Required yards must stay open to the sky except for listed features such as fences, arbors, recreational equipment and henhouses [6]; sheds aren't on that list, so keep a shed out of the required yards.
Height and size
An accessory building in Residence C-1 can't be more than 15 feet tall [4]. All accessory uses and buildings together (other than parking and driveways) can't cover more than 15% of the lot [5].
Other limits
An accessory building can't be turned into living space unless it meets the district's dimensional rules [7]. In the Floodplain Overlay District, sheds need a permit from the city's Floodplain Administrator [8]. Within 100 feet of a wetland or water body (such as Fresh Pond or Alewife Brook), check with the Conservation Commission first.
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Next steps
- Measure the shed's floor area and height; for anything over 120 sq ft, or with electrical work, contact Inspectional Services (831 Massachusetts Ave, 617-349-6100) to confirm whether a building permit is needed.
- Confirm your zoning district and its setbacks with the Community Development Department or ISD.
- Sketch a plot plan showing the shed at least the minimum setback from every lot line and outside the front yard.
- If the lot is in a floodplain or within 100 feet of a wetland, contact the City Engineer (Floodplain Administrator) or the Conservation Commission before placing it.
Common questions
- Do I need a permit for a shed in Cambridge, MA?
- It depends on size. The state building code exempts one-story sheds of 200 sq ft or less, while the city's FAQ still says 120 sq ft, so check with Inspectional Services for a shed between 120 and 200 sq ft. Every shed must meet zoning at any size.
- How far does a shed need to be from the property line in Cambridge, Massachusetts?
- In Residence C-1, an accessory building must meet the district setbacks: 10 feet front and 5 feet side and rear. Sheds aren't allowed in required yards.
- How tall can a shed be in Cambridge, MA?
- In Residence C-1, an accessory building can be at most 15 feet tall, and all accessory buildings and uses together can cover at most 15% of the lot.
- Do I need a permit for a shed in a flood zone in Cambridge, Massachusetts?
- Yes. In the Floodplain Overlay District, sheds need a permit from the city's Floodplain Administrator.
Massachusetts building code rules for sheds
The Massachusetts State Building Code (780 CMR, 10th edition) sets when a shed needs a building permit. Your town's zoning sets where it can go.
- No building permit needed for a one-story detached accessory structure used as a tool or storage shed, playhouse or similar, if the floor area is 200 sq ft or less (Residential Code R105.2).
- Bigger sheds, or any with more than one story, need a building permit from your local building department.
- Also exempt from a building permit: detached decks of 200 sq ft or less that are no more than 30 inches above grade, and greenhouses covered only in plastic film.
- The exemption covers only the building permit. Electrical, plumbing or gas work in the shed still needs its own permits, and the shed still has to meet local zoning (setbacks, lot coverage, height). Many towns set accessory-structure setbacks even for small sheds.
- Wetlands: putting a shed in a wetland resource area or within 100 feet of a wetland (or 200 feet of a river) may require Conservation Commission approval first, whatever its size.
The 10th edition took effect October 11, 2024 and has been the only code in force since July 1, 2025.
What the bylaw says
- ISD FAQ: Do I need a building permit to install a shed?, ISD Building/Electrical/Plumbing Permit FAQ
If the shed is less than 120 square feet, a building permit is not required. However, one must comply with the provisions of the Zoning Ordinance for any size shed.
- Sec. 4.21(h), Zoning Ordinance Article 4.000 Use Regulations (4.21 Accessory Uses incl. home occupations and accessory buildings; 4.22 Accessory Apartments; 4.30 use table; 4.60 Short-Term Rentals), p. 1
In Residence C-1 Districts an accessory building shall not be located nearer to any lot line than the minimum setback in the zoning district.
- Sec. 5.31, Table 5-1 (Res. C-1 row, columns 4-5: residential front and side/rear setbacks), Zoning Ordinance Article 5.000 Development Standards (5.20 yards/open space; 5.24 yard obstructions incl. fences, sheds over 6 ft), p. 1
Res. C-1 30% (1) 4 (2)(37) 45 (2)(37) 10 (3) 5 (4)
- Sec. 4.21(k), Zoning Ordinance Article 4.000 Use Regulations (4.21 Accessory Uses incl. home occupations and accessory buildings; 4.22 Accessory Apartments; 4.30 use table; 4.60 Short-Term Rentals), p. 1
An accessory building in Residence C-1, and Office-1 districts shall not exceed fifteen (15) feet in height above the ground level.
- Sec. 4.21(g)(2), Zoning Ordinance Article 4.000 Use Regulations (4.21 Accessory Uses incl. home occupations and accessory buildings; 4.22 Accessory Apartments; 4.30 use table; 4.60 Short-Term Rentals), p. 1
The total area of uses or buildings accessory to the principal use except for parking facilities and driveways may not occupy more than fifteen (15) percent of the area of the lot.
- Sec. 5.24.1, Zoning Ordinance Article 5.000 Development Standards (5.20 yards/open space; 5.24 yard obstructions incl. fences, sheds over 6 ft), p. 1
Every part of a required yard shall be open to the sky and unobstructed, except that the following features may be located within a required yard:
- Sec. 4.21(l), Zoning Ordinance Article 4.000 Use Regulations (4.21 Accessory Uses incl. home occupations and accessory buildings; 4.22 Accessory Apartments; 4.30 use table; 4.60 Short-Term Rentals), p. 1
No accessory building may be converted to a residential use unless it conforms with the district dimensional regulations specified in Section 5.30
- Sec. 20.74.1, Zoning Ordinance Article 20.000 Overlay Districts (20.60 Parkway Overlay fences; 20.70 Flood Plain Overlay; 20.1100 Alewife Overlay), p. 1
The City of Cambridge requires a permit from the Floodplain Administrator for all proposed development in the Floodplain Overlay District, including new construction or changes to existing buildings, placement of manufactured homes, placement of agricultural facilities, fences, sheds, storage facilities or drilling, mining, paving and any other development that might increase flooding or adversely impact flood risks to other properties.