Before You Build in Nashua, NH: Permit & Rule Checklist (2026)

Retaining walls in Nashua require a building permit when the wall exceeds 4 feet in height above the grade base of footing, per NRO Sec. 105-22.A.(10) of the Building Permit Fee Schedule. Residential retaining walls cost $25 minimum or $0.15 per linear foot (whichever is greater); commercial walls cost $50 minimum or $0.30 per linear foot. Walls under 4 feet do not require a stand-alone building permit but must still comply with the New Hampshire State Building Code (2021 IRC and 2021 IBC) adopted by RSA 155-A. The Building Official may require third party peer review for 'extensive retaining walls and complicated foundation designs' under NRO Sec. 105-9.B.

Nashua does not have a municipal cost-sharing or partition-fence ordinance. Neighbor fence disputes are governed by New Hampshire state law: RSA 476:1 (spite fences) and RSA Chapter 472 (partition fences). RSA 476:1 makes any fence 'unnecessarily exceeding 5 feet in height, erected or maintained for the purpose of annoying the owners or occupants of adjoining property' a private nuisance, and RSA 476:3 requires removal within 30 days of judgment with a $10 per day penalty. Nashua's residential 7-foot cap (NRO Sec. 190-44.A) is independent of the RSA 476 spite-fence threshold.

Nashua caps residential fence height at 7 feet under Section 190-44 of the Nashua Revised Ordinances (Chapter 190 Land Use, Article VI Supplemental Use Regulations), as amended by Ordinance O-23-065. Section 190-44.A reads: 'In residential zoning districts, [walls, fences or similar enclosures] shall not exceed seven (7) feet in height or interfere with traffic circulation.' Nonresidential districts have no height restriction under Sec. 190-44.B, provided the fence does not interfere with traffic circulation. Parcels directly adjacent to the Frederick E. Everett Turnpike (residential uses) may build boundary fences up to 14 feet under Sec. 190-44.C.

Nashua does not require a routine fence permit for fences that comply with NRO Sec. 190-44 height limits (7 feet residential, no limit nonresidential). A building permit through the Department of Building Safety is required only for Turnpike-adjacent boundary fences exceeding 7 feet under Sec. 190-44.C. The Department of Building Safety enforces the New Hampshire State Building Code adopted under RSA 155-A and locally implemented through NRO Chapter 105. Contact the Department at 229 Main Street, 2nd Floor, 603-589-3080, BuildingDepartment@nashuanh.gov.

Residential pool barriers in Nashua are governed by the 2021 International Swimming Pool and Spa Code (ISPSC) adopted as the Residential Swimming Pool and Spa Code of the City of Nashua under NRO Sec. 105-25 (Article VII, Chapter 105). ISPSC Section 305.2.1 requires the barrier to be 'not less than 48 inches above grade' on the side facing away from the pool. Section 305.3 requires that openings 'shall not allow passage of a 4-inch-diameter sphere.' Section 305.5 requires pedestrian access gates to 'open outward away from the pool or spa,' be self-closing, and have a self-latching device. Nashua applies these provisions as adopted; under RSA 155-A, the state framework controls.

Nashua's NRO Sec. 190-44 (Fences) does not enumerate or restrict permitted fence materials, leaving owners free to choose wood, vinyl, chain link, wrought iron, composite, masonry, or other typical materials, subject to the 7-foot residential height cap and traffic-circulation rule. The only material-specific limitation is the barbed wire restriction in NRO Chapter 150, which deems barbed wire a public nuisance unless located more than 6 feet above the ground or used for a farm or public utility. Specific use-based ordinances (trash enclosures, day care, towers) may impose opaque or solid-fence requirements in Chapter 190 supplemental use regulations.

Residential pool fencing in Nashua follows the 2021 ISPSC adopted under NRO Sec. 105-25 (per RSA 155-A as updated by HB 1681, effective December 31, 2024). ISPSC Section 305.2.1 requires the barrier to be 'not less than 48 inches above grade' on the side facing away from the pool. Section 305.3 prohibits openings allowing passage of a 4-inch sphere. Section 305.5 requires self-closing, self-latching gates that open outward, with the release on the pool side at least 3 inches below the top when the release is below 54 inches. Section 305.6 governs dwelling walls used as part of the barrier.

Residential swimming pool permits in Nashua are issued by the Department of Building Safety under NRO Chapter 105, which adopts the 2021 International Building Code, 2021 International Residential Code, and 2021 International Swimming Pool and Spa Code per New Hampshire's State Building Code (RSA 155-A, as updated by HB 1681 effective December 31, 2024). NRO Sec. 105-22.A.(2) treats 'in-ground swimming pools' as part of the building permit fee schedule (residential at $0.18 per square foot, $50 application fee). Electrical permits for in-ground pools cost $60 per NRO Sec. 105-22.C.(1)(g). Public pools are also regulated by NH DES under RSA 485-A:26 and Env-Wq 1100 per NRO Sec. 105-26.B.

Hot tubs and spas in Nashua follow the 2021 ISPSC adopted under NRO Sec. 105-25 (per RSA 155-A). Under ISPSC Section 305.7, spas and hot tubs equipped with a safety cover that complies with ASTM F1346 are exempt from the barrier provisions of Section 305 (the 48-inch fence requirement). A building permit through the Department of Building Safety is required for installation; electrical permits per NRO Sec. 105-22.C apply. Public spas (e.g., commercial, hotel, or HOA spas serving 15+ dwellings) are additionally regulated by NH DES under RSA 485-A:26 and Env-Wq 1100 per NRO Sec. 105-26.B.

Residential pool safety in Nashua is governed by the 2021 ISPSC adopted under NRO Sec. 105-25. Key safety provisions: 48-inch barrier (Sec. 305.2.1), 4-inch sphere rule (Sec. 305.3), self-closing/self-latching gates that open outward (Sec. 305.5), dwelling-wall doors leading to the pool must have an alarm meeting UL 2017 or be self-closing/self-latching (Sec. 305.6), and an approved safety pool cover meeting ASTM F1346 may serve as an alternative for hot tubs and spas. Public pools also follow RSA 485-A:26 and NH DES Env-Wq 1100 per NRO Sec. 105-26.B, including federal Virginia Graeme Baker Pool and Spa Safety Act drain-cover requirements.

Converting a Nashua garage to habitable space requires a building permit and electrical permit from the Department of Building Safety under the NH State Building Code (IRC change of occupancy from U to R-3). If the conversion adds a kitchen and separate entrance, the result is an Accessory Dwelling Unit governed by NH RSA 674:71-:73 (HB 577, 7/1/2025) — Nashua must permit the conversion by-right even where the existing garage does not meet current setbacks, and the ADU may be up to 750-950 sq ft.

Effective July 1, 2025, NH RSA 674:71-:73 (as amended by HB 577) requires Nashua and every NH municipality to allow one accessory dwelling unit (attached or detached) by-right on every single-family lot, with no minimum size below 750 sq ft and a default maximum of 950 sq ft. Nashua's pre-2025 Sec. 190-32 capped ADUs at 30 percent of the principal dwelling or 700 sq ft, required owner occupancy, and limited rental to family — those provisions are now preempted by state law to the extent they conflict. Existing detached structures (garages, barns) may be converted regardless of current setback nonconformity.

Nashua Land Use Code Sec. 190-31 (Accessory Buildings) treats unattached carports as detached accessory structures subject to a typical 4 ft side/rear setback, behind-the-front-facade rule, and the underlying district's dimensional standards in Sec. 190-16. Construction requires a building permit through the Nashua Department of Building Safety under the NH State Building Code, with engineered anchorage for the 115 mph basic wind speed in Hillsborough County. Attached carports follow the principal building's setbacks.

Nashua does not require a building permit for a shed of 200 sq ft or less, but a Land Use Permit (zoning) is required from the Nashua Department of Building Safety regardless of shed size to confirm setback compliance under Sec. 190-16 and Sec. 190-31 (accessory buildings). A plot plan showing shed location must be submitted. Sheds in residential zones (R-40, R-30, R-18, R-9, R-A, R-B) typically must meet a 4 ft side/rear accessory setback and sit behind the principal building's front facade.

NH RSA 674:74 defines tiny houses as small structures intended for year-round occupancy that meet the NH State Building Code and may be on a permanent foundation or chassis. Where Nashua permits detached ADUs under RSA 674:73 (it must, as of 7/1/2025), it must permit a single tiny house as a detached ADU — but a lot may have either an ADU or a tiny house, not both. Tiny houses must include facilities for sleeping, eating, cooking, and sanitation and meet all single-family building, fire, safety, and utility codes. Park-model RVs and tiny houses on wheels not meeting the State Building Code are not permitted as permanent dwellings.

All open burning in Nashua requires both a city permit from Nashua Fire Rescue under City Code § 110-2 (Chapter 110, Burning, Open) and a written forest-fire-warden permit under RSA 227-L:17 (Woodland Fire Control). The City Forest Fire Warden is the Nashua Fire Chief. Permits are free and issued through nashuanh.burnpermits.com in three categories: Category 1 (minimum 25-foot setback from any structure, applied for entirely online), Category 2 and Category 3 (minimum 50-foot setback, require a site visit). Burning is allowed between 5:00 p.m. and midnight, weather permitting. No permit is required only when the ground is completely covered with snow.

Backyard fire pits, chimineas, fire bowls, and any open burning of solid fuel materials (other than charcoal) in Nashua require a burn permit from Nashua Fire Rescue under Chapter 110 (Burning, Open) of the City Code and RSA 227-L:17. Permits are issued free at nashuanh.burnpermits.com. Category 1 permits cover compliant campfires with a minimum 25-foot setback from any structure; Categories 2 and 3 require a 50-foot setback and a site visit. Burning is allowed only between 5:00 p.m. and midnight, weather permitting, and only when the ground is not snow-covered without a permit. The 2021 edition of NFPA 1 (Uniform Fire Code), adopted statewide effective August 13, 2024 under RSA 153, applies as the enforcement baseline.

The Nashua Board of Public Works has cognizance, direction and full control of the planting and care of trees standing in the streets and public ways. Routine pruning of healthy trees on private property is not subject to a Nashua permit. Trees within the public right-of-way, on parks, or other public land are maintained by the City; residents must obtain Board of Public Works authorization before pruning, removing, or otherwise altering a street tree or other public tree. Eversource and other utilities prune for line clearance under their easements.

Nashua is served by Pennichuck Water Works (Pennichuck Corporation), a publicly owned utility under the Pennichuck East Utility / Pennichuck Water umbrella. Pennichuck enforces a four-level water restriction schedule that operates year-round: Level 1 odd/even house-number lawn watering; Level 2 two assigned days per week between 5:00 a.m. and 8:00 a.m.; Level 3 one assigned day per week between 5:00 a.m. and 8:00 a.m.; Level 4 total outdoor water ban. Hand-held hoses and watering cans are permitted for vegetable and flower gardens any day. Small kiddie pools (6 feet or less in diameter, 12 inches deep or less) may be filled any day.

Tree removal on private residential property in Nashua is generally not subject to a City removal permit, except where the tree is in a designated wetland or wetland buffer (Article XI of Chapter 190), within required landscape material under Article XXVII, designated for retention on an approved site plan, or in a regulated conservation area. The Board of Public Works has full control over the removal of any tree standing in a Nashua street or public way. NH RSA 231:145 governs the declaration and removal of public-highway trees deemed nuisances.