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

Town of Londonderry’s own rules

• Building code adoptedAdopted

  New construction and alterations inside Londonderry town, under the town's Londonderry building code (section 9 building code amendments of the zoning ordinance).

  • Section 9.2 amends the 2018 International Residential Code for the town (r101.1 title names the town of Londonderry; r103.1 creates the department of building safety).
  • Section 9.1 (part I) amends the 2018 International Mechanical Code and appendix chapters; the part I base-code edition for the building code was not captured.
  • Section 9.3 is demolition delay; the department of building safety is created under title V, chapter II, section III of the municipal code.

  residential code edition adopted: 2018 (with town deletions and insertions listed in section 9.2)

  “the international residential code, 2018 edition”

• Local zoningPresent (with conditions)

  Land inside Londonderry town limits: the town's own zoning ordinance (Chapter I of Title III, Land Use Code), footer-dated 08-18-2025.

  • The Title III page lists the zoning ordinance as Chapter I (pdf) and says chapter ii building code is section 5 of the zoning ordinance; the ordinance itself also contains building code amendments at section 9.
  • Zoning districts, use tables and dimensional standards in the ordinance apply to land inside town limits.

  “Town of Londonderry, NH Zoning Ordinance”

• Zoning districtsPublished

  Zoning districts inside Londonderry town (the zoning ordinance lists districts including AR-I agricultural-residential and R-III multi-family residential)

  • Table of contents also lists commercial, industrial, gateway, MUC and performance overlay districts; their standards were not all captured.

  “4.2.1 agricultural residential district (ar-i)”

• Minimum dwelling sizeSpecified

  Mobile homes inside Londonderry town only; no general minimum dwelling size for site-built homes was captured

  • Mobile homes must also be certified to 1976 HUD mobile home construction and safety standards.
  • Other manufactured housing must comply with the town building code (no size minimum stated in captured text).

  minimum mobile home floor area: >= 600 sq ft (mobile homes only)

  “Mobile homes shall have a minimum of 600 square feet”

• Minimum lot sizeSpecified

  AR-I (agricultural-residential) district, single-family and two-family lots served by municipal water and sewer, inside Londonderry town

  • Table 4-3: single family with 1-2 bedrooms 35,000 sf and 100 lf frontage; single family with 3 or more bedrooms 40,000 sf and 150 lf frontage; duplex 2-4 bedrooms (total) 52,500 sf and 150 lf; duplex 5 or more bedrooms 60,000 sf and 200 lf.
  • Lots not on municipal water and sewer are governed by a separate rule (see the 43,560 sf claim).

  minimum lot area, single family 1-2 bedrooms, municipal water and sewer: >= 35000 sq ft (3+ bedroom single family requires 40,000 sf and 150 lf frontage) · minimum frontage, single family 1-2 bedrooms, municipal water and sewer: >= 100 lf (3+ bedroom single family requires 150 lf frontage)

  “minimum lot size single family 1–2 100 lf 35,000 sf single family 3 or more 150 lf 40,000 sf”

  One more reviewed finding on this topic

  • Specified — AR-I (agricultural-residential) district, single or two-family residences not served by a municipal wastewater system, inside Londonderry town

    “not served by a municipal wastewater system shall be 43,560 SF”

• SetbacksSpecified

  AR-I (agricultural-residential) district structures, all uses, inside Londonderry town

  • If a property abuts more than one existing or proposed right of way, the building setback is 40 feet from each right of way.
  • The same AR-I list also states single family dwelling 150 feet and two family dwelling 200 feet; the captured text does not explain what those figures measure, so they are not claimed as setbacks.
  • Accessory dwelling additions must also meet all required setbacks.

  front setback: 40 feet (from property line, all uses) · side setback: 15 feet (from property line, all uses) · rear setback: 15 feet (from property line, all uses)

  “front - 40 feet 2. side - 15 feet 3. back - 15 feet”

• Building heightSpecified

  AR-I (agricultural-residential) district structures inside Londonderry town (all uses except agricultural purposes)

  • Exception: the 35-foot limit does not apply to agricultural purposes.
  • Height bonuses and three-story limits in other districts (for example the performance overlay and MUC) are not claimed here.

  maximum structure height: <= 35 feet (excludes agricultural purposes)

  “all uses with the exception of agricultural purposes) is thirty-five (35) feet.”

• Living in an RVProhibited

  Recreational vehicles used as accessory living space on residential property in the AR-I (agricultural-residential) district inside Londonderry town

  • Prohibition covers use as accessory living space only; storage limits also apply in AR-I (no more than one unregistered motor vehicle, no RV storage that creates a public nuisance).
  • The captured text does not establish a rule for RV occupancy in other districts; that is unknown from these excerpts.
  • Recreational vehicle is defined as 400 square feet or less, designed for temporary living quarters, not as a permanent dwelling.

  “shall not be used as an accessory living space”

• Manufactured homesLimited

  Occupancy of one manufactured housing unit on a lot in the AR-I district after a dwelling there is damaged by fire or other catastrophe, while the dwelling is rebuilt or repaired, inside Londonderry town

  • Temporary: not more than 12 months, or until a certificate of occupancy for the replacement structure is issued.
  • Only where a dwelling in the AR-I district was damaged by fire or other catastrophe; not a general allowance for manufactured homes.
  • Mobile homes must have at least 600 square feet and meet 1976 HUD construction and safety standards; other manufactured housing must comply with the town building code; mobile homes in special flood hazard areas must also comply with the floodplain ordinance.
  • Cites RSA 674:32 II.

  maximum occupancy period: <= 12 months (or until certificate of occupancy for replacement structure is issued)

  “it shall be permissible to occupy one manufactured housing unit on a lot for a period not exceeding 12 months, or until a certificate of occupancy for the replacement structure is issued”

• Subdividing landRegulated (with conditions)

  Subdivision of land inside Londonderry town

  • Subdivision regulations are Chapter V of the town Title III Land Use Code; the regulations text itself was not opened.
  • Site plan regulations are a separate chapter (Chapter VI).

  “chapter v subdivision regulations chapter vi site plan regulations agendas & minutes”

• Permit feesVariable (with conditions)

  Mechanical permit fees inside Londonderry town (the fee schedule is set by the Town Council)

  • The quoted rule covers mechanical work only; the amendment history also lists an amendment 'setting fees for building permits' (110), but the fee amounts were not captured.
  • No published fee schedule was found in the captured text.

  “in accordance with the schedule as determined by the londonderry town council.”

• Permit processPartial

  Building permit process inside Londonderry town, administered by the town department of building safety

  • Process details (application steps, forms, timelines) are in the municipal code title V chapter II, which was not opened.
  • Building official is the enforcing officer under the amended residential code.

  “issue any and all building permits requested when such permit is in accordance with the provisions of this Ordinance.”

Still unanswered

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

• Building permit — Building permits for new construction inside Londonderry town
• Owner-builder exemption — Owner-builder permit exemption inside Londonderry town
• Inspections — Building inspections for construction inside Londonderry town
• Certificate of occupancy — Certificate of occupancy for new dwellings inside Londonderry town
• Lot coverage — Lot coverage or impervious surface limit for single-family lots in AR-I inside Londonderry 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.

Off-grid gear

Going off-grid in Town of Londonderry means bringing your own water and power. The kit we’d start with:

• Water Crystal Quest Filter any source — well, rain, or creek — to drinking-clean.
• Power Bluetti Solar generators and home battery backup for living off the grid.
• Septic Soil percolation test kit Run your own perc test before paying an engineer — the first thing a septic office asks about.
• Water Well water test kit Bacteria, nitrates, hardness — know what the well on a parcel is really pumping.

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