New Hampshire Building Code: Which Editions Are Adopted

Direct answer

2024 New Hampshire State Building Code, effective 1 July 2026 in New Hampshire. 2024 IBC, IRC, IEBC, IMC, IPC and ISPSC, the 2018 IECC and the 2023 NEC, adopted by reference in RSA 155-A:1, IV with Building Code Review Board amendments ratified by the legislature (HB 1159, 2026). From 1 July to 31 December 2026 applicants may show compliance with either the 2021 or the 2024 codes, but not a mix of the two; from 1 January 2027 new permit applications must meet the 2024 code. The energy code stays on the 2018 IECC: a 2026 bill to move to the 2024 IECC was found inexpedient to legislate. This was checked on 2026-10-01 against New Hampshire State Building Code Review Board (Division of Fire Safety, Office of the State Fire Marshal), which is the source that controls. The cross-state comparison further down this page comes from the ICC adoption chart dated January 2024, so where the two disagree the record above is the newer one.

Content and cited inputs reviewed by Harth team · Published 2026-09-07 · Updated 2026-10-01.

What are the key takeaways?

• Current adoption: 2024 New Hampshire State Building Code, effective 1 July 2026
• Building: 2024 IBC with New Hampshire amendments
• Residential: 2024 IRC with New Hampshire amendments
• Existing buildings: 2024 IEBC with New Hampshire amendments

Which codes has New Hampshire adopted now?

2024 New Hampshire State Building Code, effective 1 July 2026.

2024 IBC, IRC, IEBC, IMC, IPC and ISPSC, the 2018 IECC and the 2023 NEC, adopted by reference in RSA 155-A:1, IV with Building Code Review Board amendments ratified by the legislature (HB 1159, 2026).

Transition: From 1 July to 31 December 2026 applicants may show compliance with either the 2021 or the 2024 codes, but not a mix of the two; from 1 January 2027 new permit applications must meet the 2024 code. The energy code stays on the 2018 IECC: a 2026 bill to move to the 2024 IECC was found inexpedient to legislate.

Local adoption: The state building code applies to all construction in New Hampshire. Towns and cities that have adopted an enforcement mechanism issue permits and inspect; the State Fire Marshal enforces in places without a building official and for state, community college and university buildings. Local rules may be stricter but not weaker.

Checked 2026-10-01 against New Hampshire State Building Code Review Board (Division of Fire Safety, Office of the State Fire Marshal). Confirm the edition and effective date for the specific permit jurisdiction before relying on it.

The cross-state record

For comparison across states, every I-Code the ICC Master I-Code Adoption Chart (January 2024) tracks, as it records New Hampshire. Where this disagrees with the record above, the record above is newer:

New Hampshire has a recorded edition year for 8 of the 17 codes: 2018 for the building, residential, mechanical, plumbing, residential energy, commercial energy, existing buildings and swimming pool and spa codes. The green construction and property maintenance codes appear as adopted by individual state or local agencies rather than as a statewide standard, so whether they apply depends on the permit jurisdiction for the project address. No adoption at all is recorded for the fire, private sewage, fuel gas, performance, wildland-urban interface, zoning and green building standard codes.

Source: ICC Master I-Code Adoption Chart (January 2024).

How New Hampshire compares with its neighbours

Statewide editions in force, checked 2026-10-01; “Local” means no state adoption, “(limited)” a state adoption for some buildings only, and * a state-titled code built on that edition.

Maine, Vermont, Massachusetts and New York differ from New Hampshire on the building code alone. A practice working across that border is working to two editions, whatever the office standard says.

Where New Hampshire sits in the national record

Of the 50 states and the District of Columbia, 10 enforce the 2024 IBC statewide, 0 a later edition, 24 an earlier one, and 17 have no statewide IBC edition in force. New Hampshire is at or ahead of the national middle on the building code, so the risk runs the other way: work arriving from a slower-moving state may be drawn to an older edition.

The residential code and the residential energy code are on different editions here — 2024 against 2018. 7 states show a split like this, which is why the energy code is worth confirming as a separate question rather than assuming it moved with the residential code.

Across all 17 codes the January 2024 ICC chart tracks, New Hampshire has a recorded edition for 8, which ranked it 20th of 51. A low count is not a gap in regulation — it usually means the state legislates through its own documents, or leaves the discipline to local adoption.

What the chart does and does not tell you

The chart's own legend matters more than the numbers:

• An edition year means one or more state or local agencies adopted that edition. It does not mean every building in the state is designed to it.
• “Some jurisdictions only” is the chart's X: the code is in use somewhere in the state but is not the standard for all buildings.
• “Not adopted” is a blank cell — no state or local jurisdiction reported adopting that code.
• “State-written code” means the state publishes its own document in place of the model edition, so the model text is a reference, not the law.

ICC states plainly that not every jurisdiction notifies it of an adoption, and this chart is dated January 2024. Treat it as the starting point for a search, never as the answer.

How to confirm the edition that governs a New Hampshire project

1. Open New Hampshire State Building Code Review Board (Division of Fire Safety, Office of the State Fire Marshal) and find the currently adopted code list with its effective date.
2. Check whether the permit authority for the project address is the state or a local programme with its own adoption.
3. Read the state amendments alongside the model edition — an amended table or definition changes the requirement even when the edition matches.
4. Record the permit application date. A code change usually applies from an effective date, and applications filed before it are normally reviewed under the previous edition.
5. Get the answer in writing from the authority having jurisdiction before it drives a design decision.

This site also hosts a transcription of the 2009 model code chapters as adopted in New Hampshire at /building-codes/us-states/new-hampshire. That is a historical reference for the 2009 editions and is not New Hampshire's current code basis.

New Hampshire code-basis worksheet

Fill this in once per project and keep it with the drawing set. Every row is a question a plan reviewer can ask, and the answer changes with the address and the application date, not with the state.

This worksheet records a determination; it does not make one. The authority having jurisdiction decides which edition and which amendments apply.

Where can you explore related guidance?

• Explore all code adoption guidance
• Maine Building Code: Which Editions Are Adopted
• Vermont Building Code: Which Editions Are Adopted
• Massachusetts Building Code: Which Editions Are Adopted
• New York Building Code: Which Editions Are Adopted

Sources and method

Adopted editions transcribed from the ICC Master I-Code Adoption Chart (January 2024), reproduced with the chart's own legend so an “X” is not mistaken for a statewide adoption. ICC notes that not all jurisdictions report their adoptions and publishes updates at iccsafe.org/adoptions. The current edition, its effective date and the state amendments are published by New Hampshire State Building Code Review Board (Division of Fire Safety, Office of the State Fire Marshal), which controls.

Source links

• iccsafe.org

• iccsafe.org

• mm.nh.gov