ADU applications jump in Boise after code rewrite

Boise's new zoning code went into action on Dec. 1, 2023, and while Boiseans won’t feel many of its effects for years, accessory dwelling units (ADUs) are making an immediate splash.

Also known as granny flats, ADUs have been championed by some as a way to make a dent in the housing crisis. The zoning code rewrite — the first major change to Boise's zoning code since 1966 — loosened restrictions on the units.

The effects are obvious: From Jan. 1, 2023 to Nov. 30, 2023, 40 ADU applications were submitted to the city. From Dec. 1, 2023 through mid-March, there have been 95 applications — 18 of which have been approved.

“Right now we’ve got 95 units that could hit the market, as something, within the next few months,” said Jessica Szelag, Boise’s deputy planning director.

The volume indicates that there was pent-up demand for this kind of housing product, Szelag said.

The new zoning code rewrite increased the size an ADU can be — from 700 square feet to 900 square feet. ADUs do not have to be owner-occupied. No parking is required.

ADUs can be made from converting an existing living area, like a basement or attic, building an addition, constructing a new detached unit or converting an attached garage, among other ways.

“It’s people who can do something right in their backyard, literally in their backyard,” Szelag said. “It’s an investment in their property. It potentially could be a secondary source of income.”

These accessory dwelling units can often run into roadblocks, which officials have tried to remove. A bill passed last year blocked home owners associations from banning accessory dwelling units. However, the bill defined ADUs narrowly, only if they were internal to a home or garage.

It’s not just ADUs. There’s been interest in different housing types and the city is hovering around an increase of 150% among all kinds of applications, Szelag said.

“Everything is just at a higher volume than we’ve seen before,” Szelag said. “... in a kind of stagnant or down economy where there’s investment happening in Boise in a pretty significant way.”