What Can You Build Without a Permit in New Hampshire? (2026)
The 30-second answer for New Hampshire
In New Hampshire, the projects you can usually build without a building permit are a small detached shed, a short freestanding deck, a fence under the height cap, a low retaining wall, and cosmetic interior work. The exact limits New Hampshire enforces are in the table below — and your city can be stricter than the state. The catch every homeowner needs to hear: even when no permit is required, the building code, zoning setbacks, and any HOA rules still apply. Permit-exempt means the paperwork is waived, not the rules.
How New Hampshire sets the rules
New Hampshire has a statewide State Building Code under RSA 155-A, currently the 2021 International Residential Code and companion ICC codes with NH amendments, effective July 1, 2024 (the 2024 IRC is scheduled for January 1, 2027). There is no statewide residential permit office — enforcement is entirely municipal, and some small NH towns have no building inspector at all, yet the owner remains legally bound by the code either way.
Permit-exempt limits in New Hampshire
These are the thresholds we verified for New Hampshire. Treat each one as the most you can usually do without pulling a permit — a stricter city amendment always wins.
| Project | New Hampshire permit-exempt limit |
|---|---|
| Detached shed / accessory building | No state building permit for a one-story detached accessory structure of 400 sq ft or less — NH amendment RE-21-03-23-R1 to IRC R105.2 (effective July 1, 2024) doubled the 200 sq ft IRC baseline. Zoning/land-use approval and setbacks still apply, and some towns enforce a lower local threshold (Nashua's own FAQ still lists 200 sq ft), so confirm with your municipal building official. |
| Deck | Follows the 2021 IRC baseline (NH left the R105.2 deck item unchanged): a deck is permit-exempt only if ALL are true — 200 sq ft or less, no more than 30 in above grade, not attached to the dwelling, and not serving the required exit door. Any attached, elevated, or ledger-bolted deck needs a permit; local zoning still applies. |
| Fence | Follows the 2021 IRC baseline: fences up to 7 ft tall are exempt from a state building permit (NH left this R105.2 item unchanged). Local zoning commonly caps fence height lower — Lebanon's official exempt-work handout lists 6 ft — and may require zoning review, so height and placement still need local confirmation. Verify locally. |
| Retaining wall | Follows the 2021 IRC baseline: a retaining wall is exempt from a state building permit only if it is 4 ft or less measured from the bottom of the footing to the top of the wall AND does not support a surcharge (no sloped fill, structure, or heavy load above it). Taller or surcharged walls require a permit. |
| Patio (on grade) | R105.2 has no specific patio item. An at-grade patio — pavers or a concrete slab on grade, 30 in or less above grade and not over a basement — generally needs no state building permit, but local zoning lot-coverage, impervious-surface, and setback rules still apply. A roofed patio, or one elevated more than 30 in, becomes a structure/deck that requires a permit. |
Baseline: 2021 International Residential Code, Section R105.2. See the national project-by-project guide for how each threshold works.
Can you do the work yourself in New Hampshire?
Yes. Under IRC R105.1 any owner or the owner's authorized agent may apply for the building permit. New Hampshire also lets a homeowner do their own electrical, plumbing, and gas work in an owner-occupied single-family residence without a trade license (RSA 319-C:15 and RSA 153:36); the work must still meet code, be permitted, and pass inspection. Some towns require a signed homeowner affidavit or a pre-permit meeting (e.g., Lebanon).
What's different about New Hampshire
Sheds up to 400 sq ft need no state building permit
New Hampshire amended IRC R105.2 (RE-21-03-23-R1, effective July 1, 2024) to double the IRC baseline: a one-story detached accessory structure of 400 square feet or less is exempt from a state building permit, versus 200 sq ft in most states. Zoning, setback, and lot-coverage approval are still required.
Enforcement is local — some towns have no inspector
RSA 155-A applies statewide, but there is no state residential permit office; each municipality enforces the code or, in some rural towns, has no building inspector at all. Where nobody inspects, the owner is still legally responsible for meeting the 2021 IRC — an exemption from inspection is never an exemption from the code.
Tents of any size are exempt on owner-occupied homes
NH's R105.2 amendment adds an item not in the base IRC: tents of any size erected as an accessory structure on an owner-occupied one- or two-family property are exempt from a building permit. Fire-code and event rules may still apply to large or public-assembly tents, so confirm with the local fire official.
"Permit-exempt" does not mean rule-free
I spent 25 years as a firefighter before I built PermitDeck, so let me be blunt about the part that gets people hurt. "No permit" never means "no rules." When a project is exempt in New Hampshire, three things are still true — and now you are the one responsible for them, because no inspector is coming to check:
- Building code still applies. An exempt deck in New Hampshire still has to meet the structural rules of IRC R507 — real footings, a proper ledger, and guards. A shed still has to carry your local snow and wind load. The code does not care whether a permit was pulled.
- Zoning and setbacks still apply. Exempt does not mean you can put it anywhere. Setbacks from property lines, easements, lot-coverage caps, and corner-lot sight lines all still bind you — and a neighbor complaint can force you to move it.
- HOA rules are separate. Your HOA architectural review is a private contract, not a government permit. You can be fully permit-exempt with your city and still be forced by your HOA to tear something out.
The big New Hampshire cities
Permits are pulled locally, so your city's building department has the final word. Here are the two largest, with a link straight to their office.
Manchester
Manchester enforces the NH State Building Code and its own zoning ordinance. Even a permit-exempt accessory structure needs a Building & Zoning application with a plot plan showing setbacks and lot coverage; a $25 non-refundable processing fee applies. Homeowners may apply as owner-builder.
Manchester building departmentNashua
Nashua requires a Land Use (zoning) permit for a shed of ANY size, and its published FAQ still exempts only sheds under 200 sq ft (not the state 400) from a building permit — confirm the current threshold before building. Submit a combined Building & Land Use application with a plot plan.
Nashua building departmentTurns out you do need a permit? We'll match you with pros who pull it
If your project crosses one of these New Hampshirethresholds, the cleanest path is to hire a licensed pro who pulls the permit in their own name and stands behind the inspection. Tell us the project once and we'll send it to up to three verified local pros. It's free, it's capped at three, and we never sell your information — the opposite of the lead-farm sites.
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What happens if you needed a permit and skipped it
Guessing wrong on the exemption is not a small risk. The common outcomes are a stop-work order, a fine (often double the normal permit fee), and being ordered to open finished work back up for inspection or tear it out. The expensive part usually lands later: unpermitted work routinely kills a home saleat the buyer's inspection, and an insurance claim can be denied if the damage traces back to unpermitted construction. Most jurisdictions do allow a retroactive (after-the-fact) permit — it costs more, but it clears the record.
Full detail: what happens if you build without a permit and how to get a building permit.
New Hampshire permit-exemption FAQs
Do I need a permit to build a shed in New Hampshire?
No state building permit is needed for a one-story detached accessory structure of 400 square feet or less, under NH's 2021 IRC amendment (RE-21-03-23-R1, effective July 1, 2024). But every town still requires a separate zoning or land-use permit and setback compliance, and Nashua's own FAQ still lists a 200-square-foot threshold, so confirm with your local building official.
Does New Hampshire have a statewide building code?
Yes. RSA 155-A adopts the 2021 International Residential Code statewide, effective July 1, 2024, but enforcement is municipal, not statewide. Many small New Hampshire towns have no building inspector; even then, the property owner is legally responsible for meeting the code. Manchester and Nashua both run building departments that require permits and inspections.
Do I need a permit to build a deck in New Hampshire?
Your deck is exempt from a state building permit only if it is 200 square feet or less, no more than 30 inches above grade, freestanding (not attached to the house), and not serving the home's required exit door. Attached, elevated, or ledger-bolted decks need a permit, and local zoning setback rules still apply everywhere in the state.
Can I do my own electrical and plumbing work in NH?
Yes. Under RSA 319-C:15 and RSA 153:36, a homeowner may do their own electrical, plumbing, and gas work in an owner-occupied single-family home without a trade license. The work must still meet code, be permitted, and pass inspection. Some towns, such as Lebanon, require a pre-permit meeting or a signed homeowner affidavit first.
Sources we verified against
- NH State Building Code amendments (R105.2 → 400 sq ft; tents), eff. July 1, 2024 (hosted by City of Portsmouth)
- City of Lebanon — Work Exempt from Building Permit Requirements handout
- NH Building Officials Association — 2021 IRC adopted, effective July 1, 2024
- RSA 155-A — New Hampshire Building Code (statute)
- City of Nashua — Permits page and Building FAQ
Every threshold on this page is anchored to New Hampshire's building code or the sources listed above. Where a number varies by city and we could not verify it, we say "verify locally" rather than guess — a permit page you cannot trust is worse than no page at all.
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