Earlier this year, there were a few attempts by city councilors past and present to change our rules around Backyard Cottages. The saga of attempting to reform them continues, but unexpectedly state level laws have thrown a curveball. Advocates for and against the city’s latest proposal have started to speak up, so lets better understand what is going on.
Backyard Cottage being added behind a duplex. A home where there was not before.
When we last left off, there were two sets of amendments. Councilor Kristen Strezo had proposed increased flexibility for floor plans and existing structures. Meanwhile former Councilor Bill White had proposed drastically reducing the scale and imposing additional constraints on home builders. During the hearing for both of those proposals, the city revealed that the state’s new ADU law interacted in strange ways with Somerville and thus necessitated a rewrite anyway. Both existing proposal went on to die in committee.
Then in September, the Planning Division released its own rewrite intended to comply with state laws. State law requires the city to allow a great deal of flexibility in ADU size and shape, and also requires us to allow internal or attached ADUs. It also prohibits the city from requiring expensive underground utilities.
State law does give cities the power to set a maximum ADU size, with some limits, and Somerville has chosen a maximum size of 1,750 square feet for external ADUs
Make no mistake, 1,750 square feet is a generously sized home, and homes that size are not likely to be cheap. However, it is about the size of most new homes in our Neighborhood Residence districts. For example, over at 192 Washington St., where a new triple decker and backyard cottage have been built recently, the cottage is only 100 square feet smaller than the average of the other three new homes.
That size, and the accompanying price tag, are the source of some new proposals to reduce the allowable size of accessory dwelling units. Some people feel that the word “accessory,” by definition, requires something smaller. Others have seized on any possible objection to find a new way to oppose housing.
That’s a huge problem: setting more requirements on size means making it harder to build. Making it harder to build means that fewer homes will get built. And if fewer new homes get built, we’ll see even faster price increases for the homes that do exist.
Going back to the 192 Washington St. example, the families that bought homes there are now not competing for other homes in Somerville. That slows the price growth on those other homes, as their money has been spent elsewhere. Repeat that process over and over again, and you can have an impact on Somerville’s prices.
Getting exact figures on price and market impact is difficult, but the state’s ADU tracker reports at least 43 detached ADUs have been approved in Somerville since the beginning of 2025. That’s a drop in the bucket compared to projects like Union Square’s tower or 299 Broadway, but ADUs get built fast, and every bit does help spread the load.
Last month, Land Use Committee took into account the multitude of opinions and impacts of ADUs and proposed amending the city’s proposal to a more modest 1152 sqft maximum. We think this is reasonable and that hope city council keeps in mind that ADUs actually need to make financial sense to be built. Meanwhile, Bill White has resubmitted his earlier amendments that would severely limit the ability for ADUs to actually be built. Somerville needs to keep ADUs as a viable option for how our city can produce new homes throughout the city.
What you can do about it
Please write to [email protected] to let them know you support item 26-1336 for flexibility for ADUs and you oppose items 26-1509, 26-1510, 26-1511, and 26-1512. Encourage councilors to vote against amendments that make it harder to build homes, and encourage them to support the housing that Somerville needs to make it a place for everyone.