Exeter, NH Zoning Regulations for Home Additions and Improvements

Planning a home addition or major improvement in Exeter, New Hampshire means working within a defined set of local rules before a shovel goes in the ground. Exeter, NH zoning regulations govern where a structure can sit on a lot, how large an addition can be, whether a permit is required, and whether extra review is needed for properties inside the town's historic districts. This guide breaks down the process using publicly available information from the Town of Exeter Building Department, the Exeter Zoning Board of Adjustment, the Exeter Historic District Commission, and New Hampshire state law, so homeowners and contractors can plan improvements with confidence.

What Zoning Regulations Apply to Home Additions in Exeter, NH?

Exeter's zoning ordinance is administered by the Town of Exeter Building Department, which handles building inspection services, code enforcement, and zoning administration for the town. The ordinance divides Exeter into zoning districts, including residential districts such as R-1, R-2, and R-4, along with overlay districts such as the Aquifer Protection Overlay District and the town's historic districts. Each district has its own rules for minimum lot area, lot coverage, building height, and setbacks, which are laid out in the ordinance's dimensional schedules.

Before designing a home addition, a homeowner needs to know:

• Which zoning district the property is located in
• The minimum front, side, and rear yard setbacks for that district
• The maximum lot coverage and building height allowed
• Whether the property falls within an overlay district, such as the Aquifer Protection Overlay District or a historic district
• Whether the proposed addition meets these requirements as of right, or whether it requires relief from the Zoning Board of Adjustment

The Town of Exeter periodically amends its zoning ordinance, with the most recent full version amended through March 2025. Because requirements are updated over time, homeowners should always confirm current standards with the Building Department rather than relying on an older printed copy of the ordinance.

What Setback Requirements Apply to Exeter Home Additions?

Setback requirements define how far a structure, including an addition, must sit from the front, side, and rear property lines. In Exeter, setback distances are set by zoning district and are listed in the ordinance's dimensional schedule (Schedule I and Schedule II). Setbacks are not uniform across town. As one example found in the ordinance, a side yard setback in certain districts is defined as equal to the side yard of the abutting property or 10 feet, whichever is less, illustrating how Exeter ties some setback rules to the existing pattern of development on a street rather than a single flat number for every zone.

Because setback distances, lot coverage percentages, and height limits vary by zoning district and by overlay district, a homeowner cannot assume the same setback that applies to a neighboring town, or even a different zoning district within Exeter, will apply to their own lot.

Any addition that extends beyond the existing footprint of a structure must show all required setback distances on the building permit application.

Key definitions that affect setback compliance include:

• Setback: The minimum required distance between a structure and a property line.
• Lot coverage: The percentage of a lot's area covered by buildings and other impervious structures.
• Building height: The vertical distance from the ground surrounding the building to the highest point of the structure, not including chimneys and similar features.
• Overlay district: A zoning layer applied on top of a base district that adds extra requirements, such as the Aquifer Protection Overlay District, which imposes additional lot area and construction standards to protect groundwater resources.

Homeowners planning additions close to a property line should request a zoning determination from the Building Department before finalizing design plans.

Do I Need a Building Permit for a Home Addition in Exeter?

Yes. Building permits serve as formal, legal permission for homeowners and contractors to begin residential or commercial construction projects in Exeter, including remodels, renovations, additions, and related electrical and plumbing work. A building permit confirms that the submitted plans have been reviewed and comply with the building codes and zoning laws adopted by the town, including the International Building Code as adopted by Exeter.

Because construction projects vary widely, the Exeter Building Department requires applicants to meet directly with staff when obtaining and completing building, electrical, or plumbing and gas permit applications. Electrical, plumbing, and gas contractors must present valid trade licenses when applying. Once work begins, Exeter's building and electrical inspectors require 24 hours' notice before scheduled inspections, including rough wiring, rough plumbing, or covering a chimney with wall material.

The Exeter Building Department is located at:

10 Front Street, Exeter, NH 03833 Phone: 603-773-6112 Fax: 603-772-4709 Hours: Monday through Friday, 8:00 AM to 4:30 PM

How Does the Exeter Historic District Affect Home Improvements?

Properties located within one of Exeter's historic districts are subject to an additional layer of review beyond standard zoning compliance. The Exeter Historic District Commission (HDC) was established in 1970 and administers Article 8 of the Town Zoning Ordinance. Its role is to safeguard the architectural heritage of the town, preserve historically significant elements of properties, and conserve property values within the historic districts.

One nationally recognized example is the Exeter Waterfront Commercial Historic District, listed on the National Register of Historic Places on December 3, 1980, with a boundary increase added on December 29, 1986. The district covers roughly 35 acres along Water, Franklin, Pleasant, High, and Chestnut Streets and Chestnut Hill Avenue, and includes buildings in Greek Revival, Federal, and Late Victorian architectural styles.

For properties within a historic district, exterior building and landscape changes that alter the external appearance of a property require prior approval from the HDC before work begins. This is formalized through a Certificate of Approval (also referred to as a Certificate of Appropriateness). Examples of work that typically requires HDC review include:

• New additions or new construction visible from the exterior
• Changes to siding, roofing, windows, and doors
• Landscape features such as patios, walkways, fences, and lighting that significantly change the site's appearance

Work that generally does not require HDC review includes interior changes that do not affect an exterior feature, and general landscaping maintenance that does not significantly change the overall appearance of the property. Because each application is evaluated on its own merits, homeowners with a property in a historic district should contact the Exeter Planning Department early in the design process, well before finalizing construction plans, since the HDC typically meets monthly and requires an application in advance of that meeting.

Can I Build an Accessory Dwelling Unit (ADU) in Exeter?

Accessory dwelling units are a specific form of home addition that is now subject to New Hampshire state law as well as local zoning. Under New Hampshire RSA 674:72, any town that permits single-family homes must allow at least one attached ADU on that lot as a matter of right. Detached ADUs remain optional at each town's discretion, and towns may attach conditions such as owner-occupancy requirements and confirmation of adequate water and septic capacity.

Exeter's zoning ordinance places additional size and use conditions on ADUs consistent with state law, including:

• An ADU within the principal structure is limited to a maximum of 900 square feet or one-third of the finished floor area of the principal structure, whichever is less, but not less than 750 square feet
• A detached accessory dwelling unit is limited to a maximum of 750 square feet
• One of the two dwelling units on the property must remain owner-occupied
• Off-street paved or gravel parking must be provided for at least four vehicles total
• Before renovation or construction begins, the property owner must provide evidence to the Building Inspector that septic facilities are adequate for both units, which may require certification from a New Hampshire-licensed septic system designer
• An expansion of an existing structure greater than 400 square feet of footprint to accommodate an ADU requires Planning Board review of the proposed site plan

Because New Hampshire's ADU law was updated in 2025, homeowners should confirm the current version of both the state statute and the Exeter zoning ordinance before designing an ADU addition.

What Is a Zoning Variance and When Do I Need One in Exeter?

A variance is formal permission to deviate from the strict requirements of the zoning ordinance, such as building closer to a property line than the standard setback allows, or exceeding a lot coverage limit. In Exeter, variances are decided by the Zoning Board of Adjustment (ZBA), a quasi-judicial body established under New Hampshire's planning enabling legislation, RSA 672 through 677, along with the local zoning ordinance.

New Hampshire law requires an applicant to satisfy a five-part test before a variance can be granted:

• The variance will not be contrary to the public interest.
• The spirit of the ordinance is observed.
• Substantial justice is done.
• The values of surrounding properties are not diminished.
• Literal enforcement of the ordinance provisions would result in unnecessary hardship.

A related but distinct type of relief is a special exception, which applies when the zoning ordinance already permits a specific use under defined conditions, and the applicant must demonstrate that those conditions are met. The ZBA also hears appeals from administrative decisions, such as a denied building permit, and applications for an equitable waiver of dimensional requirements.

What Is the Variance and Special Exception Process in Exeter?

The Exeter Zoning Board of Adjustment (ZBA) is a five-member board with five alternate members, each serving three-year terms appointed by the Select Board. The board meets on the third Tuesday of each month at 7:00 PM in the Nowak Room of the Exeter Town Office at 10 Front Street.

The general process for a variance or special exception application includes:

• Submitting a complete application, including required plans, a list of abutting property owners compiled from Exeter Tax Assessor records, and applicable fees to cover the cost of preparing and mailing legal notices
• The board scheduling a public hearing within 30 days of receiving a properly completed application
• Public notice of the hearing being posted and printed in a newspaper, with notice mailed to the applicant, all abutters, and any other parties the board considers to have an interest, at least five days before the hearing date
• The applicant, and any interested parties, having the opportunity to appear in person, or through an agent or attorney, to state their case
• The board issuing a written decision after the public hearing

If either the applicant or another affected party believes the ZBA's decision was made in error, New Hampshire law provides a right of appeal.

Building Permit vs. Variance vs. Historic District Approval: What Is the Difference?

Homeowners often confuse these three types of approval. Each serves a different purpose:

• Building permit: Confirms that construction plans comply with adopted building codes and the zoning ordinance for projects that already meet zoning requirements as of right. Issued by the Building Department.
• Zoning variance or special exception: Required when a proposed addition does not meet a specific zoning requirement, such as a setback or lot coverage limit, and the property owner needs formal relief from that requirement. Decided by the Zoning Board of Adjustment after a public hearing.
• Historic District Certificate of Approval: Required in addition to a building permit for any exterior change to a property located within an Exeter historic district, regardless of whether the project otherwise complies with standard zoning. Decided by the Historic District Commission.

A single project, such as an addition on a historic property that also requires a setback variance, may need all three approvals before construction can begin.

What Happens If I Build Without the Required Approvals?

Exeter's Building Department enforces the zoning ordinance and building codes through code enforcement and inspections. Building permit applicants formally agree, in writing, to comply with the zoning ordinance and the adopted building code as a condition of receiving a permit.

Work performed without a required permit, without a required variance, or without a required Historic District Certificate of Approval can be found in violation of the zoning ordinance, which may require costly remediation, removal, or after-the-fact approval that is not guaranteed.

Confirming requirements with the Building Department, and where applicable the Planning Department, before starting work is the most reliable way to avoid these outcomes.

How Do I Find Out My Property's Zoning District in Exeter?

Homeowners can determine a property's zoning district, applicable setbacks, and whether the property falls within an overlay or historic district by:

• Reviewing the official Exeter Zoning Map maintained by the town
• Contacting the Exeter Building Department directly at 603-773-6112
• Reviewing the current version of the Exeter Zoning Ordinance, which is amended periodically and published by the town
• Consulting the Exeter Planning Department for questions specific to historic district status or overlay districts

Because zoning maps and ordinance language are updated over time, the town's current published versions should always take precedence over older documents or general summaries, including this guide.

Frequently Asked Questions

Do all home additions in Exeter require a building permit? Yes. Building permits are required in the Town of Exeter for residential and commercial construction projects, including remodels, renovations, and additions, as well as related electrical and plumbing work.

How far must an addition be from my property line in Exeter? It depends on the zoning district and the specific setback provision that applies to that district. Setback distances are defined in the ordinance's dimensional schedules and can also depend on the setbacks of neighboring properties in some districts. Homeowners should confirm exact setback distances with the Exeter Building Department before finalizing plans.

What is the difference between a variance and a special exception? A variance allows a property owner to deviate from a specific zoning requirement, such as a setback, and requires satisfying a five-part legal test. A special exception applies when the ordinance already allows a particular use under defined conditions, and the applicant must show those conditions are met.

Can I add an accessory dwelling unit to my Exeter home? In most cases, yes. New Hampshire RSA 674:72 requires towns that allow single-family homes to permit at least one attached ADU as a matter of right, subject to size limits, owner-occupancy rules, parking requirements, and septic capacity verification under Exeter's zoning ordinance.

Does my property need Historic District Commission approval for an addition? If the property is located within one of Exeter's historic districts, any exterior change that alters the external appearance of the property, including an addition, generally requires a Certificate of Approval from the Historic District Commission before work begins, in addition to a standard building permit.

How long does the ZBA variance process take in Exeter? The Zoning Board of Adjustment schedules a public hearing within 30 days of receiving a complete application. The board meets monthly, on the third Tuesday, so total timelines depend on application completeness and the board's meeting schedule.

Who enforces zoning regulations in Exeter, NH? The Exeter Building Department is responsible for building inspection services, code enforcement, and zoning administration for the Town of Exeter.

Where is the Exeter Building Department located? The Building Department is located at 10 Front Street, Exeter, NH 03833, and can be reached at 603-773-6112 during office hours, Monday through Friday, 8:00 AM to 4:30 PM.