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Window Replacement, Siding, Doors and Decks in Merrimack, NH
Merrimack lets you swap a window or door of the same size and location without a building permit, prices deck permits by the square foot, and can inspect deck pier footings virtually. Call (978) 788-0374 or use the form. A person reads every request and replies with what happens next.
- Free for homeowners
- Town and state exterior rules on this page
- Souhegan River to the Merrimack
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Exterior work in Merrimack
What are you replacing or building?
Siding
Vinyl, fiber cement and wood siding replaced or repaired, with the lead-safe rules older houses bring.
Window Replacement
Replacement and new-construction windows, sized and installed to the energy and egress rules your town uses.
Exterior Doors
Entry, storm, patio and sliding doors, swapped in existing openings or framed into new ones.
Decks & Porches
New decks, rebuilt porches and stairs, with the footings, setbacks and permits they usually need.
Changing a window size or adding a deck?
(978) 788-0374Tell us what's changing outside and whether the lot backs onto wetland or a river, and we'll connect you with a contractor who handles Merrimack permits.
Permits
Permits for siding, windows and decks in Merrimack
What the town exempts. Merrimack's 2023 Development Guide says the town "requires a building permit for all commercial and residential construction and remodeling activities," then lists a short set of exemptions: non-structural roofing, ordinary repairs, accessory structures under 160 square feet, and replacing existing doors or windows "of the same size and location." Siding isn't named either way, so ask the building division before a re-side. Permit plans come in two sets showing foundation, floor plans, elevations and a wall section, and residential plans "must be to scale" (Development Guide 2023).
Where to file. Building permits are handled by the building division of Merrimack Fire & Rescue, which says "Inspections are required for each permit issued" (building division). Applications go through the town's OpenGov portal, and inspection requests are taken only there, with 24 to 48 hours' notice (Inspections).
Posted fees. The schedule approved in fall 2024 and effective January 1, 2025 charges porches, decks and sheds $0.68 per square foot, on top of a $35 non-refundable application fee. A re-inspection is $50, and work started before the permit carries a 100% surcharge (fee schedule).
- Building permits
- Building division, Merrimack Fire & Rescue
- Apply and book inspections
- OpenGov, 24–48 hours' notice
- Same-size window or door swap
- Exempt (Development Guide 2023)
- Decks and porches
- $0.68 per sq ft plus $35 application (effective January 1, 2025)
- Re-inspection
- $50
- Work before permit
- 100% surcharge
State rules. New Hampshire leaves permits and permit fees to its towns (RSA 155-A:2). Merrimack's own code page explains the switch to the 2024 State Building Code: it took effect July 1, 2026, with either code set accepted through December 31, 2026, and every permit request from January 1, 2027 follows the 2024 codes (NH State Building Code). The state doesn't license siding, window or deck installers; the Attorney General's office says "contractors do not need to be licensed," and advises a written contract with scope, materials, total price and payment schedule before any work or payment, references, proof of insurance, and caution about a down payment over 50% (NH AG). On a contract over $5,000 the contractor must hand you the RSA 359-G notice, and a homeowner gives written notice of a defect at least 60 days before suing (RSA 359-G). Exterior lights or deck outlets installed for pay need an OPLC-licensed electrician (RSA 319-C:15).
Lead and asbestos. On a house built before 1978, anyone paid to disturb paint must be EPA-certified once exterior work goes past 20 square feet, and window replacement is always covered regardless of size (EPA RRP for contractors). Old cement-asbestos siding falls under NHDES rules: when the job is hired out, a qualified asbestos inspector looks first and a state-licensed asbestos contractor does the removal, with notice to NHDES at least 10 working days before a major project (NHDES asbestos).
Last verified November 2026. Fees, restrictions and deadlines on this page are due for re-checking by January 2027. New England Exterior Pros is a referral service. We don't do the work or file permits; the contractor does.
Decks and porches
Decks and porches in Merrimack
What the inspector checks. The town's residential inspection checklist, revised April 6, 2020, checks footings for proper depth below the frost line, and at final looks at decks, landings and stairs: risers no taller than 7¾ inches, treads at least 10 inches, handrails and guardrails at least 36 inches high, and baluster gaps no more than 4 inches (residential inspection checklist). Merrimack posts no separate deck construction guide.
Virtual footing inspections. For small residential jobs the town allows pre-approved virtual inspections, and "Pier footings for decks, porches, sheds, and non-heated additions" are on the list (Inspections). Before digging footings, file a free Dig Safe ticket (811) at least 72 hours ahead, not counting weekends and legal holidays (RSA 374; Dig Safe).
Wetlands, rivers and flood corridors. The 2024 zoning ordinance includes a Wetlands Conservation District, a Shoreland Protection District and a Flood Hazard Conservation District tied to flood maps dated September 25, 2009 (zoning ordinance), so check with the town before a deck or porch heads toward a wet back lot. The town's 2021 hazard mitigation plan names the Merrimack River, the Souhegan River and Baboosic Brook as its flood corridors and calls the Island Drive area "particularly prone to flooding" (Hazard Mitigation Plan). For a house on a lake, pond or large river, changing the size of an attached deck in the protected shoreland takes a state shoreland permit or permit by notification (NHDES shoreland FAQ).
Merrimack's homes
Mostly post-1950 houses, few older ones
Merrimack has 10,264 housing units, 8,609 of them single-family (NHES community profile, ACS 2014–2018). Only about 5% of homes were built before 1950, against 17% across the Greater Nashua region (NH DHHS lead data brief, April 2023). Most exterior jobs here are replacing the original siding, windows and decks on later houses rather than restoring old ones, though the pre-1978 paint rules still apply to anything built before then.
Merrimack has no local historic district. Its Heritage Commission, set up in 2000, has no posted permit or demolition review role; it looks after landmarks such as the Olde Kings Highway, Simonds Rock, Chamberlain Bridge and Thornton Cemetery (Heritage Commission; historic landmarks).
FAQ
Merrimack exterior questions
Do I need a permit to replace windows in Merrimack?
Not for a straight swap. The town's 2023 Development Guide exempts replacing existing doors or windows of the same size and location. The exemption is that narrow, so a new opening or a bigger one goes through the building division first.
How much is a deck permit in Merrimack?
The fee schedule effective January 1, 2025 lists porches, decks and sheds at $0.68 per square foot, plus a $35 non-refundable application fee. Starting work before the permit is issued adds a 100% surcharge, and a re-inspection is $50.
Can the town inspect my deck footings without coming out?
Sometimes. Merrimack offers pre-approved virtual inspections for small residential jobs, and pier footings for decks, porches, sheds and non-heated additions are on that list. Every inspection is requested through OpenGov with 24 to 48 hours' notice.
Does Merrimack have a historic district?
No local historic district. The Heritage Commission, set up in 2000, looks after landmarks such as the Olde Kings Highway and Chamberlain Bridge; the town posts no permit or demolition review role for it, so exterior work goes through the normal building permit process.
What does it cost me to use New England Exterior Pros?
Nothing. Asking is free for homeowners; the contractor prices the job, and the price and contract are between you and them.
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