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Rockingham County

Rockingham County, NH Permits for Metal Carports and Garages

New Hampshire

If you are asking whether you need a permit for a carport in Rockingham County, the answer depends on your town, because Rockingham County does not issue building permits. Portsmouth's Inspection Department lists garages, carports and sheds among the new structures that need a building permit, with no size cutoff on its FAQ. Londonderry, on the other hand, dropped the permit for sheds under 200 square feet as of April 30, 2026, though setbacks still apply. Salem asks for plans with every building permit application. Check with your own town before you order so the size, location and paperwork line up.


Permit office: Rockingham County has no building permit office of its own. These city and town offices are where permits are actually issued:


When a permit is required

  • Portsmouth: the Inspection Department's FAQ says new structures including sheds, garages and carports need a building permit. The FAQ gives no size exemption for them.
  • Londonderry: as of April 30, 2026, sheds under 200 square feet need no permit. Sheds over 200 square feet still do, and a shed of 200 square feet or more must sit on footings down to the 48 inch frost depth.
  • Salem: the town's Building Permit Application states that plans are required with every submittal, and the application is good for 30 days.
  • New Hampshire rule: under the state building code amendments, a one-story detached accessory building up to 200 square feet does not need a building permit. Your town can require one anyway, as Portsmouth does, and zoning setbacks apply regardless of size.


Zoning and setbacks

Each town sets its own setbacks. Londonderry's FAQ lists 40 feet from the front property line and 15 feet from the side and rear lines in the AR-1 residential district, with 25 feet for structures that house livestock, and it says every shed must meet setbacks no matter its size. Derry's permit FAQ gives shed setbacks of 15 feet from the side and rear lines and 35 feet from the front. In Portsmouth, zoning review is normally the first step, and the city warns that missing zoning information can hold an application up for days.


What to bring

  • A site plan showing the lot, every existing structure with its size, and the setback distances to the new building (Portsmouth asks for this on most projects).
  • Plans or sketches that accurately show the scope of work. Floor plans and framing details may also be requested. Portsmouth says stamped structural plans are not needed for most residential projects.
  • In Salem, a completed Building Permit Application with plans attached. The form also asks whether the lot involves a variance, floodplain, wetlands, a historic district or Dig Safe.
  • In Londonderry, footing details to 48 inches for any shed of 200 square feet or more.


Farm buildings

A barn or equipment building on a Rockingham County farm still needs a building permit from the town, since New Hampshire has no general farm exemption from the building code. The state did adopt IBC Appendix C for Group U agricultural buildings. Zoning gives farms more room: RSA 674:32-a allows agriculture where a town's zoning is silent on it, and RSA 674:32-c lets the local board waive setbacks or other dimensional rules that don't make sense for a farm use. Bring both up with the town early.


Good to know

Portsmouth's fee schedule charges $8 per $1,000 of construction cost for one and two family residential work, with a $75 minimum, and rounds every fee up to the nearest $5. Applications go through the city's ViewPoint Cloud portal. Inside Portsmouth's Historic District, exterior work also needs a separate Historic District Commission application with eleven copies, and because the commission meets monthly, expect at least an extra month. Salem takes building permit submittals during a set permitting hour, 8:30 to 9:30 a.m., Monday through Friday.


Common questions

Do I need a permit for a carport in Rockingham County?
Usually, yes, and it comes from your city or town, not the county. Portsmouth requires a building permit for new carports, garages and sheds, and Salem requires plans with every application. Even where a small shed is exempt, as in Londonderry under 200 square feet, setbacks still apply.


Does a metal garage or shed need a building permit in Portsmouth?
Yes. Portsmouth's Inspection Department lists sheds, garages and carports as new structures that need a building permit. The fee is $8 per $1,000 of construction cost with a $75 minimum, and lots in the Historic District also need Historic District Commission review.


How far from the property line can a shed or carport go in Londonderry?
In the AR-1 residential district, Londonderry's FAQ lists a 40 foot front setback and 15 feet from the side and rear lines. Buildings that house livestock need 25 feet. These setbacks apply to every shed, including the small ones that no longer need a permit.


Sources


Rules and fees change. Call the office to confirm before you order.


See the full New Hampshire permit guide for statewide rules, farm exemptions and wind and snow ratings.


Looking at buildings? See our metal carports, metal garages and metal buildings.


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