Chilmark's Bylaw

Chilmark's annual town meeting where residents voted on a large house bylaw on April 22, 2013

Chilmark's annual town meeting where residents voted on a large house bylaw on April 22, 2013



Chilmark is a small town on the island of Martha's Vineyard in Massachusetts, known for its rolling hills, picturesque farms, and beautiful beaches. Its year-round population of 905 (as of 2014) swells dramatically in the summer, as 75% of Chilmark’s 1,606 homes are seasonal. The minimum lot size for new construction in most of Chilmark is 3 acres, though there are many buildable pre-existing undersized lots. 

The average house size is 2,350 square feet and more than half of the homes are smaller than 2,500 square feet. In recent years, the size of new houses has been getting bigger, resulting in growing public concern. Typically, larger houses are built as seasonal homes taking advantage of water views. There are 26 houses larger than 6,000 square feet; one of the largest is around 14,000 square feet. 

Cottages in Chilmark are often torn down and replaced by mega-mansions

Cottages in Chilmark are often torn down and replaced by mega-mansions

A large home in Chilmark

A large home in Chilmark


Chilmark’s large house bylaw was prepared by the Chilmark Planning Board, which held dozens of public meetings over a year and a half. It was approved by a vote of 162-51 at the April 22, 2013, annual town meeting. 

The Planning Board’s goal was to craft a bylaw that allowed reasonable use of property but reduced the negative impacts on abutters and the community at large. The aim was to differentiate between a large, highly visible house on a small property, and a well-designed, well-landscaped house on a large though barely visible property that minimizes its energy consumption and impact on water quality. Also, the aim was to allow additional floor space on larger lots, to remove the incentive to subdivide property and build even more houses. The proposed bylaw requires that applicants for larger homes go through a design review process, which is not needed for more modest homes.

The bylaw allows 3,500 square feet of floor space on a basic 3-acre lot, as of right. Owners can apply for a special permit allowing up to 6,000 square feet, with the Zoning Board of Appeals reviewing the application to ensure that the project’s environmental impacts have been minimized and mitigated. These include visual impact; effects on water quality in coastal ponds; effects on traffic, habitat, and wetlands; energy usage; and effects of exterior lighting. The bylaw allows for an additional 250 square feet for each additional acre of property; smaller lots would have 250 square feet less per acre. It also allows a one-time addition of up to 5% of the floor area, to buildings that already exceed the limit. 

The Planning Board calculated that between 2000 and 2013 eight houses had been built that exceeded the new limits. A 2016 modification to the bylaw exempts the square footage of historic homes, to provide a bonus for their preservation. Under Massachusetts law, a town is not allowed to set an absolute limit on the interior size of a house, but jurisprudence indicates that limits that vary by property size, such as in the Chilmark bylaw, are permissible.

You can download the bylaw here.


    Two years after the "big house bylaw" went into effect the fears of many who voted against the bylaw failed to manifest. The real estate market did not suffer, property values continued to rise, and the construction industry showed no significant impact. In those two years, nobody applied for a special permit to build a home greater than the size limitations.

    One unintended potential effect of the bylaw was to encourage the tearing down of historic homes in order to build a newer structure that would otherwise have been prohibited because of the size restrictions. An amendment was passed in 2015 to prevent this potential impact.

    In 2017 the town of Truro, Massachusetts passed a big house bylaw modeled after Chilmark's. The organization "Save Truro Seashore" screened One Big Home multiple times to galvanize support in their community.

    In February 2018, I (Thomas) attended the biennial review for the Chilmark big house bylaw.

    We passed our big-house bylaw in 2013, and since then, building permits have remained steady (for both new construction, additions, and renovations) and property values have continued to increase. As Peter Cook (member of Chilmark's Planning Board) stated, "It seems like there is more awareness that bigger isn’t sustainable…at least more awareness than a few years ago. The bylaw works."

    As with 2015's biennial review, the data is clear. There is no substantial downside to limiting house size.