Do You Need a Permit for a Shed in Massachusetts?

No building permit is needed for a shed in Massachusetts if it is one story, detached from the house and no more than 200 square feet of floor area. That exemption comes from the state residential code, 780 CMR 51.00 R105.2, and it covers the building permit only: zoning setbacks, wetlands rules and any wiring still apply.

So a 10 by 12 foot storage shed (120 square feet) is exempt. A 12 by 20 shed (240 square feet) is not, and neither is a two-story barn of any size.

Is the limit 120 or 200 square feet?

200, for a shed at a house. You will see 120 quoted online, and it is a real number, just from the wrong chapter.

The general chapter of the Massachusetts building code exempts sheds "not greater than 120" square feet (780 CMR 105.2). But that same chapter says detached one- and two-family homes "and their accessory structures" may follow the residential code instead (section 101.2.1). The residential code's list of work exempt from a permit puts the shed line at 200 square feet:

One-story detached accessory structures used as tool and storage sheds, playhouses, and similar uses provided that the floor area does not exceed 200 ft².

The same list exempts a few other backyard projects, including fences up to seven feet, retaining walls up to four feet and a detached deck of up to 200 square feet that sits no more than 30 inches above grade. The permit types guide walks through the full list.

Three words in the rule do most of the work. "One-story" rules out a loft barn. "Detached" means the shed is not attached to the house. And "tool and storage sheds, playhouses, and similar uses" means storage, not a bedroom, office or studio someone lives or works in.

What still applies to an exempt shed?

The exemption opens with a qualifier: it applies "except for activities which may require a permit pursuant to other laws." Three of those come up with sheds.

Zoning setbacks. Your town's zoning bylaw decides where on the lot a shed may sit, and it applies whether or not a building permit is needed. Sudbury's building department spells it out: a shed of 200 square feet or less, no longer than 16 feet, may be placed 5 feet from the side and rear property lines and 40 feet from the front, while a larger shed needs 20, 30 and 40 feet (Sudbury Building Department). Some towns ask you to file anyway so they can check placement. Danvers runs an accessory structure application for single-story sheds of 200 square feet or less that are under 10 feet tall, "to confirm that your project conforms to the setback requirements."

Wetlands. Under the state Wetlands Protection Act, work within 100 feet of a wetland, pond or stream, or 200 feet of a river, needs a permit from the local conservation commission. Marlborough's Conservation Commission lists shed installation among the simple projects that go through a Request for Determination of Applicability.

Wiring, plumbing and gas. The residential code notes that permits may be required for electrical, plumbing or gas work even when the structure itself is exempt. Running a circuit to a shed is electrical work with its own permit and inspection.

How a shed's size and use decide the paperwork

Your shed	Building permit?	Also check
One story, detached, 200 sq ft or less, storage only	No (R105.2)	Zoning setbacks; town shed registration if required
Same shed, with power run to it	No building permit	Electrical permit for the wiring
Over 200 sq ft, or two stories	Yes	Zoning setbacks for larger structures
Attached to the house	Yes, it is an addition	Setbacks for the house itself
Used as an office, studio or living space	Yes, not a storage use	Zoning use rules; electrical, heating
Within 100 ft of a wetland (200 ft of a river)	Depends on size	Conservation commission filing first

When do Massachusetts homeowners file shed permits?

Fall is busy. We counted permits whose work description mentions a shed in 2025, across the 31 Massachusetts towns in our records that had at least one (we left out "shed dormer" and "shed roof", which are house work). October had the most filings of any month, 63, just ahead of March and September at 62 each. January and February were the quietest, at 22 and 24.

County	Shed permits filed, 2025	Towns with filings
Middlesex	208	11
Plymouth	112	6
Norfolk	90	5
Barnstable	41	2
Bristol	34	2
Worcester	30	1
Hampshire	27	1
Essex	13	2
Berkshire	8	1

Of the 563 records, 449 were building permits and 102 were electrical permits for power to a shed. Where a job value was recorded (321 records), the median was about $6,400. Billerica had the most shed filings, 68, followed by Falmouth and Reading at 36 each; Middlesex County's town-by-town page shows how busy its building departments are overall. Our monthly permit reports track all construction permits across the state.

What should you ask before the shed goes in?

A short list, for the installer and the town:

1. What is the floor area? Measure the floor, not the roof overhang. At 200 square feet or less you are under the exemption; one foot more and you are not.
2. Where are my setbacks? Ask the Sudbury, Danvers or your own building department page for the zoning numbers before you pick a spot. Corner lots can have two front setbacks.
3. Does my town register sheds? Some do even for exempt sheds.
4. Is there a wetland, pond or stream within 100 feet? If so, call the conservation commission before delivery day.
5. Will it have power? If so, the electrician files an electrical permit. Our homeowner electrical and plumbing guide explains who may do that work.

If the shed is part of a bigger backyard project, masshomecomfort has local pages for Billerica, Sudbury and Danvers homeowners, among other Massachusetts towns.