Do you need a permit to replace a roof in Merrimack, NH?

Roofing questions: Merrimack, NH

Is drip edge required in Merrimack, NH?

Yes. Required on shingle roofs. New Hampshire adopts the 2024 International Residential Code without changing its drip edge rule, Section R905.2.8.5: "A drip edge shall be provided at eaves and rake edges of shingle roofs." Adjacent segments overlap by at least 2 inches, the drip edge extends at least 1/4 inch below the roof sheathing and at least 2 inches back onto the deck, it is fastened at no more than 12 inches on center, and "Underlayment shall be installed over the drip edge along eaves and under the drip edge along rake edges." The 2021 edition, which an applicant may elect during the six months after a new code takes effect, carries the same section. A reroof is held to the same chapter: "Materials and methods of application used for recovering or replacing an existing roof covering shall comply with the requirements of this chapter" (R908.1). A city or town may not change this rule: "No amendments to the technical requirements of the state building code are permitted" (RSA 155-A:3, II). Everything above is New Hampshire state law, the same in every city and town.

Can you roof over an existing roof in Merrimack, NH?

Two layers at most. New Hampshire adopts the 2024 International Residential Code without changing its reroofing section, R908 (RSA 155-A:1, IV; the State's amendments change no Chapter 9 section). Section R908.4 lets a new roof covering go over an existing one in listed cases, but "A roof recover shall not be permitted where any of the following conditions occur," and the third condition is "Where the existing roof has two or more applications of any type of roof covering." So one existing layer may be covered once, and a roof that already has two layers is torn off: "Roof replacement shall include the removal of existing layers of roof coverings down to the roof deck" (R908.3). The same section also bars a recover "Where the existing roof or roof covering is water soaked or has deteriorated to the point that the existing roof or roof covering is not adequate as a base for the additional roofing" and where the existing covering is slate, clay, cement or asbestos-cement tile. The 2021 edition, which an applicant may elect during the six months after a new code takes effect (RSA 155-A:2, I), sets the same three conditions in Section R908.3.1.1. A city or town may not change these rules: "No amendments to the technical requirements of the state building code are permitted" (RSA 155-A:3, II). Everything above is New Hampshire state law, the same in every city and town.

What building code does Merrimack, NH use?

The 2024 International Residential Code, as adopted by the State in the New Hampshire State Building Code. RSA 155-A:1, IV defines the state building code as "the adoption by reference of" the 2024 editions of the International Building, Existing Building, Plumbing, Mechanical, Swimming Pool and Spa, and Residential Codes, the 2018 International Energy Conservation Code and the 2023 National Electrical Code, "including all amendments reviewed and approved by the board as of October 10, 2025, and ratified by the legislature in accordance with RSA 155-A:10." That edition has applied since July 1, 2026. For six months after a new code takes effect, RSA 155-A:2, I lets a permit applicant show compliance "using either the code in effect just prior the effective date of the code adopted under RSA 155-A:1, IV, or the code adopted under RSA 155-A:1, IV, but not a combination of the 2 codes"; the code in effect before was built on the 2021 International Residential Code. The State's amendments to the 2024 code replace its Chapter 1 with a State administrative chapter and change no section of Chapter 8, Roof-Ceiling Construction, or Chapter 9, Roof Assemblies. The code reaches existing houses: "All buildings, building components, and structures constructed in New Hampshire shall comply with the state building code and state fire code," and "the alteration, renovation, rehabilitation, repair, removal, or demolition of all buildings and structures previously erected shall be governed by the provisions of the state building code" (RSA 155-A:2, I). It applies in every city and town: the code "shall be effective in all municipalities ... without further local modification, except as permitted by this section" (RSA 155-A:3, VII). A city or town may amend only the code's administrative provisions, such as permits and fees, and those amendments are not enforced unless the State Building Code Review Board confirms them: "No amendments to the technical requirements of the state building code are permitted" (RSA 155-A:3, II). Enforcement is local and set up by each city or town: its legislative body "is hereby empowered and authorized to establish a local enforcement agency" (RSA 155-A:3, I). Where a city or town has no local enforcement agency or contracted third party, "the state fire marshal or the state fire marshal's designee may enforce the provisions of the state building code and the state fire code ... upon written request of the municipality" (RSA 155-A:7, I). Everything above is New Hampshire state law, the same in every city and town. In Merrimack the Building Division, part of the Fire and Rescue Department, enforces the code; the division's own page says permit applications are submitted online through the town's permit portal and that inspections are required for each permit issued.