Merrimack, New Hampshire Building Permit Guide

The Town of Merrimack’s Building Department (Building Code Enforcement & Inspectional Services), part of Merrimack Fire and Rescue at its headquarters at 432 Daniel Webster Highway (603-420-1730), issues building, electrical, plumbing, mechanical, gas, solar, septic and demolition permits for a Hillsborough County town of about 30,000. Applications and inspection requests go through the town’s OpenGov portal, and residential building work is charged $0.68 per square foot plus a $35 application fee. Zoning, subdivision and site plan sit with Community Development at Town Hall on Baboosic Lake Road, on a separate line.

The name needs disambiguating twice over. The Town of Merrimack is in Hillsborough County — Merrimack County is a separate county in the middle of the state containing the capital, and a search or a filing that conflates the two lands in the wrong place entirely. The Merrimack River, meanwhile, runs along the town’s eastern edge and through Manchester, Nashua and Concord.

This guide covers the Town of Merrimack in Hillsborough County, New Hampshire. Nashua, Bedford, Amherst, Hollis and Litchfield are separate municipalities with their own building officials; Merrimack County is a different county elsewhere in the state; and no New Hampshire county issues building permits in practice.

What requires a building permit in Merrimack?

Merrimack’s permit checklist sets out which applications a project needs. Building work starts with a building application, signed off by Planning and Zoning where the project needs it; a sewer connection needs the Wastewater Division’s signature; and each trade files its own permit.

Merrimack’s own permit rules

A permit becomes void without notice if no inspection is completed within six months of issue, and a substantial change to the work needs a new approval charged at the minimum fee. Work begun before the permit is issued carries a 100% surcharge, and an abatement can be requested from the Town Manager. Residential plans need not be engineered but must be accurate, legible and to scale; commercial, industrial and multi-unit residential plans must be stamped by a New Hampshire licensed professional.

Every building in New Hampshire must meet the state building and fire codes (the 2024 codes since July 2026). Only towns that have adopted an enforcement mechanism issue local permits, and any local amendment must be administrative and confirmed by the state. New Hampshire rules

Merrimack building department: who handles permitting

The Building Department, part of Merrimack Fire and Rescue, is the permitting authority inside the town, administering the New Hampshire State Building Code through the enforcement mechanism Merrimack has adopted; it also carries out code enforcement, and the Fire Department issues the certificate of occupancy. Community Development at Town Hall administers the zoning ordinance and subdivision and site plan review. The State Fire Marshal permits state, university and community college buildings, the environmental department issues shoreland, wetlands and sewage approvals, and the Office of Professional Licensure and Certification licenses electricians, plumbers and gas fitters statewide.

Permit types

Residential permits

Electrical, building, gas, mechanical, plumbing, solar and demolition applications are all filed through the OpenGov portal; forms that are not online can be downloaded as PDFs. Plans must be drawn to scale and show the foundation size, depth and reinforcing, room uses, door and window locations, egress, insulation R-values and finishes. The square footage behind the fee is the sum of all usable floor space, including the basement and any unfinished or accessible attic. A septic permit follows a test pit inspection and an NHDES-approved design, and a sewer connection needs the Wastewater Division’s sign-off.

Building or remodeling a home here? Alliance handles residential permit filing, so the crew isn't waiting on the counter.

Commercial permits

New construction, renovation and changes of use on commercial property are pre-approved by Community Development for zoning and site plan compliance before the Building Department reviews them. Plans must carry the stamp of a New Hampshire licensed design professional, and large or complex projects may need third-party plan review and third-party inspections on a pre-arranged schedule. Fire prevention permits for oil burners, oil tanks and LP storage tanks are not available through the portal and go to the Fire Marshal’s office, which also takes the fire alarm, sprinkler and range hood applications.

For tenant improvements and new commercial builds, Alliance handles commercial permit expediting through issuance. More on this: commercial building permits explained.

The state permits that sit outside the town

Docks and other shoreline structures on the river and ponds need state approval, and the New Hampshire Department of Environmental Services approves shoreland, wetlands and septic designs and asbestos removal before demolition. Before a certificate of occupancy, every town department on Merrimack’s CO checklist must sign off.

New Hampshire has no general contractor licence; the contractor carries the duty to meet the state codes, and the trades hold state licences. New Hampshire rules

Merrimack permit costs and fees

Fees come from the town’s Code Enforcement & Inspection Fee Schedule, approved September 12 and October 10, 2024 and in effect since January 1, 2025. Every permit also carries a non-refundable application fee: $35 for one- and two-family homes and $50 for commercial work. Fees are assessed once every department has approved the plans, and the applicant is told the amount and the conditions of approval.

A permit can be cancelled within six months of issue if no approved work has begun. On a written request approved by the Building Official, the town keeps the application fee and 25% of the permit fee and refunds the rest.

Trade permits and who may pull them

Trade work follows the town’s permit process where the town enforces, and is done by tradespeople holding the state licence their trade requires. New Hampshire rules

How to apply for a Merrimack building permit

Review, corrections and what actually causes delay

Review checks completeness first and then building and fire code compliance. Questions, other departments’ approvals and required revisions go back to the applicant before approval, and fees are only assessed after every department has signed off, so a missing zoning or wastewater signature holds up the whole permit.

Inspections in Merrimack

Merrimack no longer books inspections from voicemail: every request goes through the OpenGov portal and is scheduled first come, first served, with 24 to 48 hours’ notice. Inspections run 9:00 am to 12:00 pm and 1:00 pm to 3:00 pm on Mondays, Wednesdays and Fridays, and 9:00 am to 1:00 pm on Tuesdays and Thursdays. The work must be finished and fully accessible, and every trade on the job must confirm it is ready, before the request goes in.

For small residential jobs only, the office may pre-approve a virtual inspection by video call, followed by photographs sent by email: pier footings for decks, porches, sheds and unheated additions; open trenches for sewer, septic or electrical conduit; and insulation in finished basements and minor renovations. Re-inspections from the third visit on cost $50 each.

Merrimack permit search and official resources

• Merrimack Building Division — the permit process, staff and CO checklist
• Merrimack OpenGov permit portal — building and trade applications and inspection requests
• Building Permit Applications — online and downloadable forms, and the fire prevention exception
• Code Enforcement & Inspection Fee Schedule — effective January 1, 2025
• Permit checklist: what permits or certificates does my project need?
• Building Permit Application Procedures — plan requirements and the approval process
• Inspections — scheduling windows and virtual inspections
• Building Something? — snow load, waterfront, generators and other guidance
• New Hampshire State Building Code — the adopted editions and the statewide amendments
• RSA chapter 155-A — the statute on the code, permits, enforcement and appeals

Frequently asked questions

Is Merrimack in Merrimack County?

No. The Town of Merrimack is in Hillsborough County. Merrimack County is a separate county in the center of the state, containing the capital.

Who issues building permits in Merrimack?

The town’s Building Department, part of Merrimack Fire and Rescue, at 432 Daniel Webster Highway (603-420-1730), through the OpenGov portal. No New Hampshire county issues building permits in practice.

How much is a building permit in Merrimack?

For a one- or two-family home, $0.68 per square foot of usable floor area for new space, additions, alterations and accessory structures, plus a $35 application fee. Commercial work pays the same rate with a $100 minimum and a $50 application fee.

How do I book an inspection?

Only through the OpenGov portal, with 24 to 48 hours’ notice; the office no longer takes requests by voicemail. Small residential jobs can sometimes be inspected by video call if the office approves it in advance.

Which code applies?

Merrimack applies the state building code: the 2024 international codes since July 1, 2026, alongside the 2018 energy code and the 2023 electrical code. Permit applications received through December 31, 2026 may instead follow the previous 2021 set, used whole rather than mixed. New Hampshire code editions

Who approves work near the river or a wetland?

The state environmental department, through the shoreland and wetlands approvals. Those come before the local building permit.

Where do I file, Town Hall or the highway office?

Building permits go to the Building Department at Fire and Rescue Headquarters, 432 Daniel Webster Highway, which also handles code enforcement. Zoning, subdivision and site plan questions go to Community Development at Town Hall, 6 Baboosic Lake Road, on (603) 424-3531.

Simplify Merrimack permitting with Alliance Permitting

Merrimack is a town, a river and a county, and only one of them takes your permit. We file at the right office, name the right county, and sequence the state approvals ahead of the build.

Ready to break ground in Merrimack sooner?

Send us the scope and the parcel. We confirm the review path with the Merrimack Building Department, assemble the submittal, file it, and track it through issuance — corrections included.

More New Hampshire permitting guides

This guide is provided by Alliance Permitting for general information about Merrimack permitting. Requirements, fees, and procedures change; confirm details with the permitting authority before relying on them.