Merrimack Zoning Overview

Merrimack is a town in Hillsborough County, New Hampshire, with a population of approximately 26,632 (2020 Census). Located in southern New Hampshire along the Merrimack River, the town manages land use and development through its zoning ordinance, administered by Merrimack Community Development.

Merrimack's zoning ordinance divides the town into several districts, including two residential zones, two commercial zones, and an industrial zone. The R district requires 40,000 sq ft minimum lots, while R-1 requires 20,000 sq ft.

Key Zoning Districts

Merrimack's primary residential zoning districts include:

• R (Residential) — Minimum 40,000 sq ft lots with 40 ft front, 20 ft side, and 30 ft rear setbacks. Maximum height of 35 ft.
• R-1 (Residential) — Minimum 20,000 sq ft lots with 30 ft front, 15 ft side, and 20 ft rear setbacks. Maximum height of 35 ft.

Commercial and industrial districts include:

• C (Commercial) — General commercial district for retail, office, and service uses
• C-1 (Highway Commercial) — Highway-oriented commercial district for larger-scale retail and services
• I-1 (Industrial) — Manufacturing, warehousing, and related industrial uses

ADU Regulations (Accessory Dwelling Units)

New Hampshire state law (RSA 674:72-73) requires all municipalities to allow ADUs (Accessory Dwelling Units) as a matter of right on any property with a single-family dwelling. Merrimack must comply with this state mandate. Key points:

• One ADU is permitted per single-family lot
• The ADU may be attached to or detached from the primary dwelling (subject to local standards)
• Municipalities cannot prohibit ADUs but may adopt reasonable regulations regarding size, parking, and other dimensional standards
• Contact Merrimack Community Development for the town's specific ADU application requirements and any local dimensional standards

Building Code

Merrimack follows the NH State Building Code (RSA 155-A), which is based on the International Building Code (IBC) and International Residential Code (IRC). All construction must comply with the state building code.

Development Process

Development in Merrimack generally requires obtaining the appropriate permits from the town's planning and building departments. The process typically involves:

1. Zoning Verification — Confirm that your proposed use is permitted in the applicable zoning district
2. Site Plan Review — For commercial, multi-family, and certain other projects, submit a site plan to the Planning Board
3. Building Permit — Apply for a building permit with construction documents
4. Inspections — Schedule required inspections during construction
5. Certificate of Occupancy — Obtain final approval before occupying the structure

For projects that do not conform to existing zoning, property owners may need to seek a variance or special exception from the Merrimack Zoning Board of Adjustment (ZBA).

Key Considerations

Before starting any development project in Merrimack, property owners should:

• Verify the zoning classification of their property
• Review setback, height, and lot coverage requirements for the applicable district
• Check for any overlay districts or special regulations
• Determine if the property is in a flood zone using FEMA's flood map service
• Confirm whether HOA covenants or deed restrictions apply
• Contact Merrimack Community Development at (603) 424-2331 for pre-application guidance

Disclaimer: This guide provides general information about zoning in Merrimack, NH and should not be relied upon as legal advice. Zoning codes are subject to change. Always verify current regulations with Merrimack Community Development before making development decisions.