ADU chart

ADU chart

This chart shows how many accessory dwelling unit permits have been granted in Newton each year since 2007. City of Newton Planning Department

A new state housing law has a section requiring communities to allow accessory dwelling units, and now Newton has to change its zoning to match the new state law.

An accessory dwelling unit is an apartment added on to a property in the form of an internal ADU (commonly known as an in-law apartment) or detached (like a guest house that’s up to code as a rental).

Newton’s zoning ordinance has allowed ADUs since 1987.

New state regulations are still being finalized, but the Newton Planning Department made a draft ordinance recommendation based on what those state regulations are likely to entail, Deputy Planning Director Jennifer Caira told the Zoning and Planning Committee this week. It’s possible the state regulations will be done the same day the law goes into effect, Feb. 2.

“We’d like to have our ordinance up to date as close to that as possible, to limit confusion,” Caira said.

Some background

Newton’s ADU policy has evolved since ADUs were first allowed almost 40 years ago. In 2017, the ADU ordinance was updated to allow internal ADUs of up to 1,000 square feet by-right (without needing a special permit).

A few years later, the City Council updated it again to allow detached ADUs of up to 900 square feet by-right, and setback requirements were relaxed.

“Newton’s actually been ahead of things when it comes to ADUs,” Caira said. “We do not have that much that needs to be substantially updated as part of this new state law.”

Despite Newton being more permissive than its neighbors regarding ADUs, fewer than 1 percent of single- and two-family homes in Newton (excluding condos) have an ADU.

Of the 122 ADUs in the city, almost three quarters are internal ones. Among the 25 percent that are detached, most are built in old carriage houses in historic districts.

“It hasn’t been a very popular option for adding housing, which I think is why every few years the City Council has revisited this, adding amendments trying to make this a bit more attractive,” Caira said.

Working with state law

The Affordable Homes Act, signed last year by Gov. Maura Healey, changed Chapter 40A of the state’s Zoning Act to require all communities to allow ADUs in all zones where single-family homes are allowed.

Newton’s existing zoning requires owner occupancy on the property getting an ADU. But with the new state law, owner-occupancy requirements are not allowed. So hypothetically, someone could buy a dozen houses, build ADUs behind all of them, and rent out the houses and the ADUs, effectively doubling their number of available rental units.

Some other changes needed in the city ordinance include:

Relaxed setback requirements (how far an ADU has to be from the edge of the property)
Changes to language defining floor area and habitable space (total amount of floor space vs. living space)
Getting rid of a local requirement for ADUs to have a front entrance
Removing the 700 square feet footprint limit
Removing any “unreasonable” design standards.
And doing nothing would mean nothing.

“Even if we don’t pass the ordinance, this will go into effect Feb. 2,” Caira clarified.

Newton already allows ADUs for single- and two-family homes, so Caira said there isn’t much the city has to change with where ADUs are allowed.

“We would add on to what we have, but it probably wouldn’t really expand the allowance,” she said.

Space formula

Currently, Newton allows an internal ADU by-right (no special permit) if the total living space of the ADU is 33 percent or less of the total living space of the primary home on that lot, or if the ADU is smaller than 1,000 square feet, whichever is smaller. An ADU of up to 40 percent of the primary home’s living space is allowed with a special permit.

Under that formula, if a house has 2,500 square feet of living space, the owner can add an attached ADU with up to 825 square feet of living space if all the setback requirements can be satisfied, and that house could get a 1,000-square-foot ADU (40 percent of primary home size) with a special permit.

The proposed amendments to comply with state law would make it so that the ADU has to have 50 percent of the gross floor space that the main home has. The owner of that 2,500-square-foot house could add a 1,000-square-foot ADU by-right, if setback requirements are met. A special permit would allow up to 1,200 square feet for an attached ADU.

For detached ADUs, current ordinance says a homeowner can build an ADU with 50 percent of the living space the primary home has, or 900 square feet, whichever is lower. With a special permit, the homeowner can build an ADU with up to 1,500 square feet of living space.

The state law requirements for detached ADU zoning are similar to what’s already in Newton’s ordinance, except the formula goes by gross floor space instead of living space.

The biggest opportunity with the state law sits with moderate-sized homes, not the palatial estates we see popping up on top of retaining walls around the city.

“The difference here really happens in the 2,000 to 3,000-square-foot home range,” Caira explained. “Under existing rules, to max out that 1,000 square feet for an internal ADU, you need at least a 3,000-square-foot home. This won’t change anything for homes that are bigger than 3,000 square feet, because your by-right max is still 1,000. But it means now a 2,000 square foot home could max out the ADU site.”

Get back or get short

Hurry up and wait

Caira said there could be other things the city has to change when the state’s final draft of regulations is released, including the city’s limit of four unrelated people living in one property without a special permit.

The city will hold a public hearing in the next few weeks to update residents about the new state law and local ADU zoning changes.

“Speaking with the Law Department, our latest thought is that we should wait until the regulations are finalized and we can have a clean draft that we know is addressing all of those regulations before setting a public hearing,” Caira said. “We won’t be out of compliance in any way, because we know that on Feb. 2 they’re in effect, but there are still a few things we’re trying to work through.”

Baker cautioned against waiting too long, since budget season starts in the spring and then comes summer. So the committee set a public hearing for its Feb. 24 meeting, allowing for time between the release of the regulations and the public hearing.

“It’s with the understanding that if everything falls apart, we can extend it, but I really want to move this forward,” Baker said.

You can watch the entire ADU zoning presentation online.

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