Nashua, NH Accessory Structures: Carport Rules (2026)

Nashua's Land Use Code addresses carports as detached accessory structures under Sec. 190-31 (Accessory Buildings). Detached carports must comply with the side/rear accessory setback for the underlying residential district — typically 4 ft from side and rear property lines, the same standard Sec. 190-32 uses for ADUs. Accessory structures must sit behind the front facade of the principal building (no carport in the front yard). The maximum height of an accessory structure is less than the principal building (typically 18-20 ft in residential zones). The carport may not exceed the maximum lot coverage of the underlying district in Sec. 190-16 (R-40 ~25 percent, R-30 25 percent, R-18 30 percent, R-9 35 percent, R-A 40 percent, R-B 50 percent). Attached carports — structurally connected to the principal building — must meet the principal building's front, side, and rear setbacks under Sec. 190-16. Construction requires a building permit through the Nashua Department of Building Safety under the NH State Building Code (IRC 2018 with NH amendments) with engineered anchorage and footings designed for the Hillsborough County basic wind speed of 115 mph. Snow load design under the NH State Building Code is approximately 50 psf in Nashua. Roofing materials and architectural style should be consistent with the principal dwelling. Permanently enclosing a carport with walls converts it to a garage and triggers a new building permit and full IRC requirements (fire separation, vehicle barrier, garage door). Converting a carport to habitable space requires a change-of-occupancy building permit and triggers ADU analysis if a kitchen and separate entrance are added (see garage-conversions and adu-rules subcategories).