Bill Mandates Duplex Housing Construction As A Matter of Right

Two years after a sweeping housing bond bill declared small accessory dwelling units could be built in any single-family district, the state Senate wants to double down on zoning up. The chamber’s economic development bill, which lawmakers have teed up for a vote next week, includes a provision that would require municipalities to allow duplexes as-of-right on all residentially zoned lots, meaning the projects would not require special variances. These projects would still be “subject to reasonable regulations” on septic system access, site plan review, and design factors.  State Sen. Julian Cyr, whose hometown of Truro just advanced a similar policy through its zoning task force, said the duplex zoning proposal is “a simple but incredibly meaningful reform.”           

“It’s making the housing that we’re providing more affordable,” Cyr said. “It’s making new construction of smaller-scale housing more within reach for residents in Massachusetts, especially this next generation, where we really can’t afford to live in the state because of decades of lackluster housing production,” said the 40-year-old lawmaker.  Undoing the right to have an area zoned strictly for single-family homes would also represent a seismic shift in state law, taking aim at a sacrosanct pillar of suburban zoning codes. Almost 60 percent of Massachusetts’s roughly 3 million homes are single-family houses, according to the state. Beacon Hill has been working to squeeze into almost every legislative vehicle policies that can help meet the goal of building 222,000 new housing units by 2035 to meet pent-up demand.

Housing advocates have been calling for greater “infill” density in areas that can support it but have been held back because of strict zoning requirements. The duplex move, they say, is promising but still shy of their dream scenario.

The Senate proposal is an “important provision,” said Jesse Kanson-Benanav, executive director of Abundant Housing Massachusetts. “We have an extreme shortage of homes, throughout the Commonwealth, that’s driving this cutthroat competition for housing. We really need every strategy to get the various homes at various price points that we need.” But groups like Abundant Housing are looking for more. Kanson-Benanav said his organization has been pushing new statewide zoning allowing up to five units on a lot as-of-right, where there is adequate utilities access. He pointed out that states like Maine and Vermont allow up to four units as-of-right on lots with access to water and sewer.  ( This article is a reprint from an article in Commonwealth Magazine on July 20, 2026)