New Hampshire — Code Adoption Summary
Adoption model: Statewide-mandatory. A major code-cycle transition lands 2026-07-01 (2024 I-Codes + NEC 2023), with a 6-month dual-compliance window — very current and time-sensitive right now. Last verified: 2026-07-03 Confidence: verified Primary sources: NH Division of Fire Safety — https://www.firemarshal.dos.nh.gov/laws-rules-regulatory/state-building-code · ICC NH
Statewide adopted codes — new cycle effective 2026-07-01 (dual-compliance through 2026-12-31)
| Code family | Adopted edition | Notes | Source |
|---|---|---|---|
| Building / Existing | 2024 IBC / IEBC | eff. 2026-07-01 | firemarshal.dos.nh.gov |
| Residential | 2024 IRC | eff. 2026-07-01 | " |
| Mechanical / Plumbing | 2024 IMC / IPC | NH = IPC; eff. 2026-07-01 | " |
| Pool/Spa | 2024 ISPSC | eff. 2026-07-01 | " |
| Electrical (NEC) | NEC 2023 | eff. 2026-07-01 | " |
| Energy | IECC 2018 — NH explicitly RETAINED the older 2018 IECC rather than adopting 2024 IECC | notable outlier — confirm this is intentional, not an oversight, before citing | " |
Transition window: 2026-07-01 through 2026-12-31 is a dual-compliance period — permits may be submitted under either the 2021 (prior) or 2024 (new) code cycle. Mandatory 2024-cycle compliance begins for all permits from 2027-01-01. Also: as of 2026-07-01, local amendments are limited to administrative matters only — technical local amendments are being phased out.
Adoption model & precedence
- Codes are statewide-mandatory; local technical amendment authority is being curtailed as of the 2026-07-01 cycle (administrative-only going forward) — NH is moving toward tighter uniformity.
- AHJ = local building department, applying the statewide edition (dual-compliance window notwithstanding).
Major cities / counties
| Jurisdiction | Notes | Building dept. |
|---|---|---|
| Manchester | statewide code | manchesternh.gov |
| Nashua | statewide code | nashuanh.gov |
| Concord | statewide code | concordnh.gov |
AHJ fallback (when local adoption is unverified)
- State baseline (current cycle, eff. 2026-07-01): 2024 IBC/IRC/IMC/IPC, NEC 2023, IECC 2018 (retained, not 2024).
- Action: during the dual-compliance window (through 2026-12-31), confirm whether the specific permit was filed under the 2021 or 2024 cycle.
Change log
- 2026-07-03 — created; verified new 2026-07-01 cycle (2024 I-Codes + NEC 2023), retained IECC 2018, dual-compliance window through 2026-12-31, and the new limit on local technical amendments.