In Westport the value of an older house is often the value of what can replace it. A $5 million purchase at 11 Beachside Common in October 2025 became a $22.8 million new-construction listing five months later. That math only works if the lot allows the house you have in mind. What follows is the checklist, in roughly the order each item will matter.
1. The zone and the lot
Westport’s residential zones set minimum lot sizes. A lot smaller than its zone’s minimum may still be buildable if it predates the rules. Confirm that with Planning and Zoning.
| Zone | Minimum lot |
|---|---|
| Residence AAA | 2 acres |
| Residence AA | 1 acre |
| Residence A | 0.5 acre |
| Residence B | 6,000 square feet |
| Residence C | Multifamily |
Two rules in the regulations catch buyers. Steep land, with slopes of 25 percent or more, counts toward lot area only in limited part. And total coverage counts pools and tennis courts at 50 percent of their area. Coverage limits, which cap how much of the lot buildings and other structures can occupy, are a primary constraint on the size of the house. Ask the Planning and Zoning office for the limits that apply to the specific lot and zone, and have an architect run the numbers before you bid.
2. The demolition clock
Any building at least 50 years old and larger than 500 square feet is subject to Westport’s demolition delay ordinance. The delay is 180 days, waived if no one objects. Put it in your schedule and your carrying costs.
If the house is in one of the town’s seven local historic districts or is one of its 22 designated local historic properties, the Historic District Commission can refuse demolition altogether, and exterior changes visible from a public way need a Certificate of Appropriateness. Our story on how Westport saves old houses lists the districts.
3. Sewer or septic
Sewer service is generally available south of the Merritt Parkway and generally not north of it. If the lot relies on septic, the septic system often sets the size of the house.
The Aspetuck Health District, based on Bayberry Lane in Westport, reviews additions, added bedrooms and pools under the state’s B100a rules. Owners must show space on the lot for a full replacement septic system, with at least three test pits about seven feet deep and a percolation test. A buyer should commission that testing during the contract period, not after closing.
4. The water
Near the water, Westport’s coastal area management rules apply. The coastal boundary runs at least 1,000 feet inland, and farther where tidal wetlands or the 1 percent flood zone reach inland. Since Oct. 1, 2025, every new single-family house inside Connecticut’s coastal boundary needs coastal site plan approval under Public Act 25-33, and plans in flood hazard areas are referred to the state Department of Energy and Environmental Protection.
In a mapped flood zone, a new house’s lowest floor must be at or above the base flood elevation, plus the freeboard the town requires. That can add height, stairs and cost. Our flood zone field guide explains how to check the maps, which are changing this fall in the Saugatuck River watershed.
5. A second unit
Westport allows accessory dwelling units. Detached units must sit at least 10 feet from the main house, the Westport Journal reported in 2025, noting that about 45 detached ADU permits had been issued since 2021. Other limits summarized by 06880 include a maximum footprint of 850 square feet on lots up to 1.5 acres, owner occupancy, a minimum rental term of six months, adequate septic or sewer capacity and three off-street parking spaces. Confirm the current rules with Planning and Zoning before you plan around them.
The price per square foot
New construction trades at a premium. In September the average Westport single-family house sold for $668 a square foot. A new house at 5 Fraser Road sold in 2025 for about $824 a square foot, and the planned new build at 11 Beachside Common is asking about $1,763. Our report on the price of new has the details.
Sources
- Town of Westport, Zoning regulations, effective April 1, 2022, 2022
- Town of Westport, Demolition delay ordinance, accessed Oct. 2026
- Town of Westport, Local historic districts and local historic properties, accessed Oct. 2026
- Town of Westport, Engineering Department, accessed Oct. 2026
- Aspetuck Health District, B100a information sheet, September 2025
- Carmody Torrance Sandak & Hennessey, Connecticut legislature sweeps all coastal single-family housing under local zoning and DEEP review, Oct. 15, 2025
- Westport Journal, P&Z, 10 feet must separate house and ADU, July 4, 2025
- 06880, Accessory dwelling units, accessed Oct. 2026
- Patch, Westport property slated for demolition listed as new build for $22-plus million, March 20, 2026
