New Hampshire Building Code: Permits, Inspections, and Penalties

The New Hampshire building code, defined in RSA 155-A, is the set of construction standards you must meet before anyone occupies a new or renovated structure in the state. It incorporates current editions of the International Code Council and National Fire Protection Association model codes, with state-specific amendments, and it applies whether you’re framing a new house, replacing a water heater, or opening a commercial space. In practical terms, compliance means getting a permit before you start, using licensed tradespeople for electrical, plumbing, and mechanical work, passing inspections at set stages, and finishing with a certificate of occupancy. Skip any of those, and you’re looking at daily fines, stop-work orders, or a building the town will not let you use.

Which Codes Apply to Your Project

Under RSA 155-A:1, IV, the state building code incorporates several model codes by reference. The current editions in force are the 2021 International Building Code, the 2021 International Residential Code, the 2021 International Plumbing Code, the 2021 International Mechanical Code, the 2018 International Energy Conservation Code, the 2021 International Existing Building Code, the 2021 International Swimming Pool and Spa Code, and the 2023 National Electrical Code. Each carries New Hampshire amendments adopted by the State Building Code Review Board, so the state version is never identical to the model code as published.¹

Which of these apply to you depends on what you’re building. Detached one- and two-family homes and townhouses up to three stories fall under the IRC. Everything else — commercial buildings, larger residential structures, mixed-use — falls under the IBC. The trade codes apply on top of whichever main code governs your building.

Who Enforces the Code Where You Are

Enforcement is local by default. Municipal building departments review permit applications, conduct inspections, issue certificates of occupancy, and can order work stopped for code violations. Many municipalities also layer their own ordinances on top of the state code, so your local rules may be stricter than RSA 155-A alone.²

New Hampshire has many small towns without a local building inspector. In those communities, the state fire marshal performs inspections and enforces the building code directly. RSA 155-A:7 requires the selectmen and the state fire marshal to provide information about both local and state appeals processes when they issue any permit or notice of violation.³

When You Need a Permit

You need a building permit from your local building department (or from the state fire marshal, if your town has no local office) before starting construction, renovation, or demolition. The list of work that triggers a permit is broader than many homeowners expect. Beyond new construction, permits are required for roofing, decks, fences, swimming pools, furnace replacements, water heater installations, window and door replacements, retaining walls, and demolition of any structure.⁴

The application requires detailed construction plans. Commercial projects and multi-family buildings get more rigorous plan review than a residential addition or deck. Fees vary by municipality and generally scale with project size and estimated construction cost. The department checks the plans against structural, safety, and zoning rules, and may send them back for revisions before approving.

Permits generally expire if work does not begin within six months to a year, depending on the municipality, though extensions are usually available on request. If your project disturbs one or more acres of land, you also need a federal stormwater discharge permit under the EPA’s Construction General Permit, which requires erosion and sediment controls in place before you break ground.⁵

How Inspections Work

Once your permit is issued, the building department inspects at key stages, and work generally cannot proceed past one phase until the inspector verifies it meets code. Typical checkpoints are the foundation, rough framing, insulation and vapor barriers, rough electrical and plumbing, and a final inspection before occupancy.

You or your contractor must schedule inspections in advance. Most municipalities require at least 24 hours’ notice; the state fire marshal’s office requires 48 hours.² If the inspector finds problems, you get a written correction order and work on the affected area stops until you fix them. Some municipalities charge re-inspection fees.

The final inspection is the one that matters most. It confirms the building meets fire safety, accessibility, energy efficiency, and all other code requirements. Only after it passes will the department issue a certificate of occupancy, which is your legal authorization to use the building. Processing the certificate itself can take several business days after the passing inspection.⁶

Standards by Building Type

Residential

Homes covered by the IRC (detached one- and two-family dwellings and townhouses up to three stories with separate egress for each unit) can use conventional wood-frame construction with more flexible framing allowances than commercial codes.⁷ The code puts significant weight on insulation, air sealing, and ventilation.

Manufactured homes (factory-built housing on a permanent chassis) are on a different track entirely. They are regulated under federal standards at 24 CFR Part 3280, which preempt the state building code and local ordinances. Each manufactured home carries a HUD data plate certifying compliance with the federal standards in effect when it was built.⁸

Commercial

Commercial buildings under the IBC face stricter structural, fire protection, and accessibility requirements. The code classifies buildings by occupancy type, and each classification has its own fire-resistance ratings, maximum heights, egress rules, and emergency lighting requirements. Steel or reinforced concrete framing is common where wood framing would be adequate for a home.

Accessibility adds another layer. New Hampshire’s amendments require at least 60 percent of public entrances to be accessible, and assembly, educational, institutional, business, and mercantile buildings over 1,000 square feet must install power-operated automatic doors at accessible entrances.⁷ Commercial buildings must also comply with the federal 2010 ADA Standards for Accessible Design, which apply to newly constructed and altered public accommodations and government facilities.⁹

Multifamilyh3>

Multifamily housing with four or more units first occupied after March 1991 must meet the Fair Housing Act’s design and construction requirements. In buildings without an elevator, ground-floor units must include accessible features such as wider doorways, accessible routes through the unit, and reinforced bathroom walls for future grab bars. In buildings with an elevator, all units must include those features.¹⁰

Electrical, Plumbing, and Mechanical Work

These trades require licensed professionals and separate trade permits. Electricians must hold a state license under RSA 319-C, administered by the Electricians’ Board within the Office of Professional Licensure and Certification. Most electrical work needs a permit, including new wiring, panel upgrades, and service changes, and inspections follow the 2023 NEC with New Hampshire amendments.¹

Plumbers are licensed under RSA 329-A, with permits required for major work such as new sewer connections, water service lines, and gas piping. Inspections follow the 2021 IPC. Given the state’s climate, the plumbing code puts particular emphasis on frost protection, pipe insulation, and backflow prevention.

Mechanical work, including HVAC installation and ductwork, follows the 2021 IMC. Failing any trade inspection stops the work until corrections are made, and serious or repeated violations can bring fines, failed final inspections, or action against the tradesperson’s license.

Energy Code Minimums

New Hampshire currently enforces the 2018 IECC with state amendments. Most of the state sits in climate zones 5 and 6, so the code demands substantial insulation and tight construction. For new residential construction in these zones, the code requires ceiling insulation of R-49 or higher, wood-frame walls with at least R-20 cavity insulation, and maximum air leakage of 5.0 air changes per hour at 50 pascals. Commercial buildings meet separate IECC provisions covering lighting, HVAC equipment, and building envelope.⁷ These are minimums; many builders exceed them because heating costs make better insulation pay back quickly.

Fire Safety

The state fire code, defined in RSA 153:1, VI-a, is separate from but closely linked to the building code. It adopts NFPA 101 (Life Safety Code, 2021 edition) and NFPA 1 (Uniform Fire Code, 2021 edition), each with amendments adopted by the state Board of Fire Control.¹¹

Commercial buildings and multi-unit residences face the most demanding requirements, including automatic sprinkler systems, fire alarms, marked exit routes, smoke barriers, and emergency lighting. The State Fire Marshal’s Office oversees compliance for high-risk occupancies such as schools, healthcare facilities, and places of public assembly.¹²

One point catches many owners off guard: renovations to existing buildings must meet the current fire code, not the code in force when the building was built. A major renovation can trigger sprinklers, upgraded alarms, or additional exit routes. Fire code violations can bring citations, correction orders, or closure of the building until the hazards are resolved.

Environmental Hazards That Trigger Extra Rules

Older buildings and New Hampshire soil conditions add three environmental layers.

For lead paint, any renovation, repair, or painting project that disturbs painted surfaces in a home, child care facility, or preschool built before 1978 must be performed by an EPA-certified lead-safe contractor. This federal rule applies to hired contractors. Homeowners working on their own home are generally exempt unless they rent the property, run a child care center there, or flip houses for profit.¹³

For asbestos, an owner or operator must inspect for asbestos-containing materials before demolishing or substantially renovating any building. Federal NESHAP regulations require notification to the state before any demolition. For renovations, notification is required when the project will disturb more than 260 linear feet, 160 square feet, or 35 cubic feet of regulated asbestos-containing material.¹⁴

New Hampshire is a high-radon state, and radon-resistant construction is strongly recommended for all new residential buildings. The EPA’s five basic features are a four-inch gravel layer beneath the slab, heavy-duty plastic sheeting over the gravel, a vertical PVC vent pipe from the gravel through the roof, sealed foundation cracks and openings, and an electrical junction box in the attic for a future vent fan.¹⁵ New Hampshire Housing requires radon mitigation piping as standard equipment in projects it finances, so an active system can be activated if post-construction testing shows radon above the EPA’s action level of 4.0 picocuries per liter.

Appealing a Decision or Violation

If you disagree with a building official’s interpretation or a notice of violation, you can appeal. RSA 155-A:7 requires every local enforcement agency, and the state fire marshal in towns without one, to give you information about the appeals process when they issue a permit or violation notice. Filing an appeal of a notice of violation or a code official’s decision cannot be subject to a fee.³

Appeals of local decisions typically go first to a local board of appeals. Decisions of the state fire marshal can be appealed to the State Building Code Review Board, which also hears appeals of fire code variances and exceptions.¹⁶ If administrative appeals do not resolve the dispute, either party can take the matter to New Hampshire’s superior courts.

What Noncompliance Costs

Building without a permit, ignoring a stop-work order, or leaving violations uncorrected gets expensive quickly. Municipalities may charge double permit fees for work performed without a permit and may require the removal of unauthorized construction.

Under RSA 676:17, a person who violates a local ordinance, building code provision, or condition of an approved permit faces a civil penalty of $275 per day for a first offense and $550 per day for each subsequent offense. Those daily fines begin accruing after the conviction date, or after the date the violator receives notice and the violation continues.¹⁷

Serious violations involving structural deficiencies or life safety hazards can go further. The building department or fire marshal may condemn the property, making occupancy illegal until the hazards are corrected. Persistent noncompliance can bring court-ordered corrective measures, and severe or willful violations can lead to criminal charges. For commercial buildings that violate ADA accessibility requirements, federal civil penalties can reach well into six figures for repeat violations.

1
NH.gov. State Building Code
2
NH Division of Fire Safety. State Building Permit Program
3
New Hampshire General Court. New Hampshire Code 155-A7 – Enforcement Authority
4
New Hampshire General Court. New Hampshire Code 155-A4 – Permit Required
5
US EPA. Construction General Permit (CGP) Frequent Questions
6
Windham, NH. Building Safety Division
7
New Hampshire Building Code Amendments. Summary of 2021 Building Code Amendments Effective July 1, 2025
8
eCFR. 24 CFR Part 3280 – Manufactured Home Construction and Safety Standards
9
ADA.gov. ADA Standards for Accessible Design
10
eCFR. 24 CFR 200.929a – Fair Housing Accessibility Guidelines
11
New Hampshire. State of New Hampshire List of Adopted Building and Fire Codes
12
Cornell Law School. NH Admin Code He-P 814.23 – Fire Safety
13
US EPA. Lead Renovation, Repair and Painting Program
14
US EPA. Overview of the Asbestos National Emission Standards for Hazardous Air Pollutants (NESHAP)
15
U.S. Environmental Protection Agency (EPA). Radon-Resistant Construction Basics and Techniques
16
Legal Information Institute (LII). NH Admin Code Bcr 103.02 – Duties of the Board
17
New Hampshire General Court. New Hampshire Code 676-17 – Fines and Penalties