Zoning, building permits and septic rules in Town of Amherst, New Hampshire

Town of Amherst’s own rules

• Building permitRequired

  Buildings and structures erected or structurally altered inside Amherst town, including mobile-home placement.

  • No permit may issue for a lot with an outstanding recorded town-rule violation, except a permit required to correct that violation.

  “No building or structure shall hereafter be erected or structurally altered [...] until a building permit has been issued”

• InspectionsRequired

  Most construction and development within Amherst town.

  • The town says inspection requirements vary with the type of work.

  “Building permits and inspections are required for most construction and development within the town”

• Certificate of occupancyRequired

  Buildings or structures erected or structurally altered inside Amherst town.

  • The Building Inspector/Code Enforcement Officer must find conformity with the ordinance, health, safety, building laws, and permit representations; new commercial and industrial construction also requires as-built plans before issuance.

  “No building or structure hereafter erected or structurally altered shall be occupied or used until a Certificate of Occupancy has been issued”

• Local zoningPresent (with conditions)

  Land inside Amherst town, New Hampshire.

  • Uses, construction, alterations, and enlargements must conform to the regulations of the zoning district in which the land is located.

  “buildings, or land shall hereafter be used, constructed, altered, or enlarged only in conformity with regulations specified herein”

• Zoning districtsPublished (with conditions)

  Zoning districts inside Amherst town.

  • The ordinance requires use and construction to conform to the regulations of the district where land is located.

  “For the purpose of this ordinance, the Town of Amherst is divided into the following districts”

• Accessory dwellingsLimited

  Accessory dwelling units on single-family lots inside Amherst town.

  • One attached or detached ADU is permitted on a single lot; it may be no more than 70% of primary-residence gross heated floor area, no more than 1,100 square feet, and no more than two bedrooms. It is prohibited with attached housing, condominiums, and manufactured housing.

  maximum ADU floor area: <= 1100 square feet (Also no more than 70% of existing gross heated floor area of the primary residence.) · maximum bedrooms: <= 2 bedrooms

  “One (1) attached or detached accessory dwelling unit is permitted on a single lot”

• Who permits septicLocal (with conditions)

  Septic-system permits inside Amherst town.

  “This office is responsible for review and issuance of all building and construction related permits, septic system permits, inspections”

• Septic permitRequired

  New and replacement septic systems inside Amherst town.

  “Permits are generally required for: All new construction [...] New and replacement septic systems”

• Subdividing landRegulated (with conditions)

  Subdivision plans inside Amherst town.

  • The town publishes Land Development Regulations, including Part 2 Subdivision Regulations.

  “the Amherst Planning Board adopts the following regulations governing the subdivision of land in the Town of Amherst, New Hampshire.”

• Driveway accessRequired

  Residential-lot access in Amherst town.

  • Access is from required frontage on a publicly maintained road, or a Planning Board-approved private road; shared driveway use is limited to no more than two immediately adjacent residential lots and subject to listed conditions.

  “Access to a residential lot [...] shall be by a driveway and shall comply with the requirements of RSA 674:41.”

• Building in a floodplainRequired

  Proposed development in Amherst special flood hazard areas.

  • Applies only to proposed development in any special flood hazard area.

  “All proposed development in any special flood hazard area shall require a permit.”

• Permit feesPublished (with conditions)

  Building and planning permits and applications inside Amherst town.

  • The town page labels the Building and Planning Permit Fee Schedule as updated August 11, 2026.

  “Building and Planning Permit Fee Schedule UPDATED AUGUST 11, 2026”

• Permit processPublished (with conditions)

  Permit applications inside Amherst town.

  • Applications are submitted by email or in person at Town Hall; payment in full is required at submission and review does not begin until payment is received; no work may begin without approval.

  “Permit review will not commence until payment is received.”

Rules another office applies inside Town of Amherst

Town of Amherst does not set these itself; the county, a health district or the state does, and they apply to every address inside its limits.

• Building code adoptedAdopted (with conditions)

  Construction within Amherst town.

  • The town page identifies the listed State Building and Fire Codes as effective July 1, 2026.

  “Effective July 1, 2026, the State of New Hampshire adopted the following codes:”

• Minimum lot sizeDistrict specific (with conditions)

  Residential/Rural Zone (RR) in Amherst town.

  • The minimum area may contain no defined wetland, floodplain, or slopes greater than 20%.

  minimum lot area: >= 2 acres (Minimum area excludes wetlands, floodplain, and slopes greater than 20%.)

  “The minimum lot area shall be two (2) acres.”

• SetbacksDistrict specific (with conditions)

  Dwellings, buildings, structures, and ADUs in Amherst's Northern Rural Zone.

  • A front setback may instead be the distance needed to be no closer than an existing structure; corner-property street side setback is 50 feet.

  front setback: >= 50 feet (Or no closer than an existing structure.) · side and rear setback: >= 40 feet (Corner street side is 50 feet.)

  “shall be set back at least forty (40) feet from the side and rear lot lines.”

• Building heightDistrict specific (with conditions)

  New principal dwellings, buildings, and structures in Amherst's Northern Rural Zone.

  • No structure may have more than four floors/levels including basement and attic levels; increased total structure area is also subject to a 15% floor-area-ratio limit.

  maximum height: <= 40 feet (New principal dwelling, building, or structure.)

  “No new principal dwelling, building, or structure shall be constructed to a height greater than forty (40) feet.”

Still unanswered

We looked and could not find an official answer yet. Silence is not permission; ask Town of Amherst or Hillsborough County directly.

• Owner-builder exemption — Owner-built residential construction inside Amherst town.
• Lot coverage — Residential development inside Amherst town.
• Camping on your land — Temporary camping on private land inside Amherst town.
• Tiny homes — Tiny homes inside Amherst town.
• Septic inspection — Septic systems inside Amherst town.

Each answer was extracted from an official source and independently re-checked against that source by a second reviewer. That is an evidence check, not legal advice. Rules change; confirm with the authority before you buy or build.