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NH Building Permits: What Homeowners Need to Know

Updated 2026-10-10 · 6 min read

How NH building permits work: the state building code, what your town enforces, which projects usually need a permit, who pulls it, and the inspections.

One state code, enforced by towns

New Hampshire has a single State Building Code under RSA 155-A. It applies in every municipality and sets the minimum requirements for all buildings. The code is built from national model codes with New Hampshire amendments, reviewed by the State Building Code Review Board.

Permits, however, are local. Under RSA 155-A:2, issuing permits and collecting fees is reserved for cities, towns, counties and village districts that have set up enforcement under state law. A town that wants to enforce the code adopts an ordinance, which the Review Board must confirm. The ordinance can include local amendments that are not less stringent than the state code, and as of July 1, 2026, the State Fire Marshal's office says local amendments are limited to administrative matters. The NH Division of Fire Safety (the State Fire Marshal's office) posts the municipal building code ordinances and amendments that have been confirmed.

If your town doesn't enforce the building code, the code still applies to your project. You just may not have a local inspector checking it. The State Fire Marshal's State Building Permit Program covers projects in towns without code enforcement only when the town has asked for help in writing. For buildings other than one- and two-family homes in those towns, the contractor must notify the State Fire Marshal about the type of construction before work begins (RSA 155-A:2). The same section makes contractors responsible for meeting the code.

Which code editions apply right now

The code is in transition as of October 2026. According to the NH Division of Fire Safety, the State Building Code moved to the 2024 International codes effective July 1, 2026. That includes the 2024 International Residential Code (IRC), Building Code (IBC), Existing Building Code, Mechanical Code, Plumbing Code and Swimming Pool and Spa Code, all with NH amendments. The 2023 National Electrical Code also applies. The energy code stays at the 2018 International Energy Conservation Code with NH amendments.

From July 1 to December 31, 2026, permit requests can be submitted under either the 2021 or the 2024 codes. Starting January 1, 2027, all permit requests must follow the 2024 codes. Under RSA 155-A:2, an applicant using the transition period can pick one code set but not a mix of the two, and the code in effect when the town receives your permit application is the one that governs the work under that permit.

Most homeowners never need to read the code. But if your project is being designed around the end of 2026, ask your builder which edition the plans follow.

What usually needs a permit

Each town sets its own permit list and exemptions, so the only reliable answer comes from your building department. As an example, the City of Dover requires a building permit to build, enlarge, alter, move or demolish a structure, to change a building's use, or to install or alter equipment regulated by the building code. Some examples of how the details vary from town to town:

Re-roofing is a good example of how towns differ. Manchester's FAQ lists paving, roofing, siding, window replacement, pools, sheds and signs as needing permits, and says fences and retaining walls need permits too. Nashua's FAQ says a permit isn't required to re-roof a one- or two-family home, though the work must still meet code. Nashua also says sheds under 200 square feet don't need a building permit, but a land use permit is required for a shed of any size.
Dover's FAQ says simple, normal maintenance and repairs under $2,500, sheds under 200 square feet, and fences up to 7 feet tall don't need a building permit (Dover FAQ).
Nottingham requires a permit for all new construction, including porches, pools, garages and sheds over 145 square feet, and for most renovations. Smaller sheds still need a permit, at no charge (Nottingham FAQ).
Electrical, plumbing and gas work often need their own permits, separate from the building permit, and generally must be done by a licensed tradesperson unless an exception in state law, such as a homeowner exception, applies. Ask your town how it handles trade permits. See our licensing guide.
State permits can be required on top of local ones, for example for septic work (septic guide) or projects near lakes and wetlands (shoreland guide).

Who should pull the permit

Under RSA 155-A:4, the person responsible for the construction has to get the permit before work starts. Homeowners doing their own work generally need permits too. Dover's FAQ answers "yes" when asked whether a permit is required for a homeowner working on their own house. Nottingham states that licensed contractors need to pull their own permits.

Manchester's FAQ says either the homeowner or the contractor may apply for the building permit, but licensed plumbers, electricians and gas fitters must apply for their own trade permits. The only exception is a resident single-family homeowner. Manchester also requires a licensed contractor for all plumbing and electrical work in multi-family, rental and commercial properties, and says it's the homeowner's responsibility to make sure a permit has been applied for and approved before work begins.

If you hire a contractor, they should normally apply for the permit in their name, which makes them answerable to the inspector for the work. The NH Insurance Department says homeowners should be cautious if a contractor asks them to get permits in their own name. Put who is responsible for permits in your written contract (see our hiring checklist).

What to expect: plans, review time and inspections

Requirements and timelines vary, but a few town FAQs give a sense of the process:

Plans: Dover asks for a full plan set for new construction and additions, covering floor, foundation, framing and site plans. It does not require stamped plans for one- and two-family homes. Nottingham asks for scaled plans, a site plan showing setbacks, a state-approved septic design, and a completed energy code worksheet.
Zoning and review deadlines: under RSA 155-A:4, a building official can't issue a permit for work that won't comply with zoning, building codes or planning board regulations. The official must approve or deny a completed application within 30 days, or within 60 days for nonresidential projects and residential projects with more than 10 dwelling units.
Review time: Dover says review may take upwards of 1 to 2 months after a complete application. Nottingham says it has 30 days to act, and most permits are reviewed within 24 to 48 hours once a complete application and all fees are in.
Inspections: Dover lists the typical sequence as foundation (before backfill), then rough-in for framing, electrical, plumbing and mechanical, then insulation, fire stopping and a final inspection. Not every inspection applies to every project. Dover suggests giving at least 2 business days' notice when scheduling.
Expiration: in Nottingham, building permits expire one year after issue and can be renewed. Manchester says work must start within six months of issue and be finished within twelve, and a permit expires after more than 180 days of inactivity unless an extension is granted. Check your own town's rule.

Why it's worth doing right

A permit and inspections give you an independent check on work you can't see once the walls are closed. They also leave a record that buyers, lenders and insurers may ask about later. Before any project, call or check the website of your town's building department. Tell them what you plan to do and ask what permits, plans and inspections they require.

This guide is general information, not legal advice. Local rules differ and change, so your building official has the final word.