(Illustration via Pixabay)

A DECADE AGO, I co-chaired Natick’s Tiny House Study Committee. The question we kept coming back to has only gotten more urgent: Why has it become so hard to build a modest house in an established Massachusetts neighborhood? Question 7 won’t fully answer that, but it goes after one real piece of it.

Drive through many Greater Boston suburbs and you can see the problem. An older 900- or 1,200-square-foot single-family house goes on the market. The land is expensive and zoning allows only one home, so the financially rational choice is often to replace it with a 2,400-, 3,000-, or 3,600-square-foot house. Then we all complain about McMansions.

Question 7, the Starter Home ballot measure, would change one part of that equation. It would establish a statewide baseline allowing a single-family home on a residentially zoned lot with at least 5,000 square feet of land, 50 feet of frontage, and access to public water and sewer. Critics understandably see a loss of local zoning authority. But it is fair to ask what our current rules are producing. That’s why I’ll be voting yes.

Consider a 5,000-square-foot lot measuring 50 by 100 feet. If local rules require 10-foot side setbacks, which the measure would let towns keep, only about 30 feet of building width remains. That is closer to a townhouse than to the large houses replacing older homes. Zoning affects which houses make economic sense to build. A 1,200- or 1,500-square-foot home should not be an unusual sight in a neighborhood of 2,400- and 3,600-square-foot houses.

Question 7 would not guarantee that such houses get built. Nothing in the measure ensures that new homes will be constructed or that they will be starter-sized. Construction costs, interest rates, and land prices remain what they are.

An analysis conducted by the Center for State Policy Analysis at Tufts University estimates that cities and towns would lose some authority over roughly 850,000 parcels. Most of those already allow single-family homes or additional development, so the measure would perhaps change the development status of about 200,000. Its central estimate is around 750 additional homes per year statewide, with a plausible range of 350 to 1,200. That would increase single-family construction by roughly 15 percent and overall housing production by about 5 percent. In its words, the impact would be “real but modest.”

Why so few homes from so many parcels? Parcels aren’t blank rectangles, and I’ve spent much of my career as a planner and an urban designer studying building footprints and neighborhood form. Consider a house that is 50 or 60 feet wide side to side. Add 10 or 15 feet of yard on each side, and a property with 100 or 150 feet of frontage may have no practical way to carve out another 50-foot-wide lot. If the house sits near the middle, the property may need 180 or 200 feet of frontage before a split is realistic.

Then there are wetlands, irregular lot shapes, driveways, utility locations, topography, and plain old homeowner preference. Someone who bought a one-acre property (43,560 square feet) may have no interest in selling off the side yard and putting another house next door on a 5,000-square-foot parcel.

So the larger question is whether zoning should continue to make smaller houses on smaller lots extraordinarily difficult to build. Question 7 addresses one constraint: minimum lot requirements that can prevent a single-family house even where water, sewer, and adequate street frontage already exist.

The loss of local authority is real but bounded. According to the ballot summary, cities and towns could still reasonably regulate a home’s height, its distance from neighboring buildings, open space, parking, and whether it can be rented short-term. That preserves several of the main tools communities use to shape how new homes fit in. What remains open is how “reasonably” gets interpreted, since the Executive Office of Housing and Livable Communities could issue guidance or regulations to administer the law. Local control shouldn’t mean that the only viable new house in a desirable suburb is a large, expensive one.

When we studied tiny houses in Natick in 2016, the point was never that everyone should live in one. The point was choice. A healthy community should be able to make room for a 1,500-square-foot starter home even on a street where newer houses are 2,500 or 3,500 square feet.

Question 7 will not transform Massachusetts neighborhoods overnight. But it can give homeowners, builders, and communities more room to create the smaller homes that zoning has made difficult to build.

In a housing market with too few choices, making room for one more kind of home is a good place to start.

Ganesh Ramachandran is a planner and urban designer, and chair of the Natick Affordable Housing Trust Fund.