Backyards, basements, garages: Could ADUs be Boise’s answer to housing crunch?
The square footage of so-called mother-in-law units? Pretty small. But interest in building and renting out these “accessory dwelling units”?
It seems to be growing by the day.
With Boise-area housing prices out of reach for many residents, officials have tried to get creative about ways to increase the density – and thereby, they hope, affordability – of housing in the city. One such plan: Make it easier for homeowners to furnish or build smaller units on their property – think, a room over a garage, or a separate dwelling in the backyard.
So far in 2024, the city has seen a spike in applications to build these units, more commonly known as ADUs.
The city said it has received nearly 40 applications so far this year and is on track to receive 100 by year’s end, compared with last year’s total of 48. Interest in these units initially jumped in 2021, with 82 applications – the most the city received since 2000. Interest is highest in the North End and Central Bench neighborhoods.
Crystal Rain, the planning and zoning manager for the city’s Planning and Development Services, told the City Council on Tuesday that the “surge” in interest may be due in part to the passage of the city’s modern zoning code last year. The new code made it easier to build ADUs by removing a requirement for owners to live on the property, increasing their maximum size to 900 square feet, and removing requirements to add parking spots for each unit.
Residents want to “be part of the solution” to the city’s housing crisis, Rain said.
To spur development of ADUs, city officials tried a pilot program, offering residents financial incentive and technical assistance to build units on their property in exchange for residents’ agreement to rent those units at amounts affordable to people earning 80% or less of the annual median income for up to 10 years. For a single tenant, rent could be as high as $1,249 per month.
There was “no shortage of interest” in ADUs even before the city updated its zoning code, Brian Woodward, the chief operating officer of Leap Housing Solutions, told the City Council.
But the pilot failed, said Kyle Patterson, the city’s director of innovation and performance. Ultimately, the financial incentives offered weren’t enough to offset high interest rates, rising construction costs, and some homeowners’ unwillingness to charge low rents for so long a period.
| % of AMI | 1 person | 2 people | 3 people | 4 people |
| 100% | $68,865 | $78,653 | $88,511 | $98,300 |
| Max rent | $1,722 | $1,966 | $2,213 | $2,458 |
| 80% | $49,950 | $57,050 | $64,200 | $71,300 |
| Max rent | $1,249 | $1,426 | $1,605 | $1,783 |
| 60% | $37,440 | $42,780 | $48,120 | $53,460 |
| Max rent | $936 | $1,070 | $1,203 | $1,337 |
| 50% | $31,200 | $35,650 | $40,100 | $44,550 |
| Max rent | $780 | $891 | $1,003 | $1,114 |
| 30% | $18,750 | $21,400 | $24,100 | $26,750 |
| Max rent | $469 | $535 | $603 | $669 |
Source: HUD 2023 Home Investment Partnership Program income limits
Still, Patterson told the City Council, his office “learned a lot” about the barriers to building these units from the dozen or so homeowners who had expressed serious interest in participating – information the city can incorporate into future policy changes.
The city is also piloting mobile “tiny homes,” which are usually 200 to 400 square feet but still have basic amenities like a bed and kitchen. That program will soon expand to include recreational vehicles, Patterson told council members.
“The idea was that we need more housing that’s affordable to folks on a Boise budget,” Patterson previously told the Idaho Statesman. “The hope is that because these are very small homes, they might be more affordable.”
This story was originally published April 2, 2024 at 7:17 PM.
