ADUs gaining popularity in Boise since regulations relaxed last year


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Tami Springer and her husband’s retirement plan is a two-story, dark blue structure where a rickety garage used to stand. 

When their small North End home started to burst at the seams, they started planning to replace their aging car storage area with an accessory dwelling unit (or ADU for short) with a two-bay garage and a studio on top. Their plan is to use the space for guests and, occasionally, renters looking to stay in the city on business for weeks at a time. 

[‘Denser in certain areas:’ Inside Boise’s plan for a zoning code rewrite]

Maybe in the future it can be a living space for their elementary school-aged son when he is an adult or they can rent it out to someone taking care of Springer and her husband when they are well past retirement age. The Springers are planning to move into the ADU when they have retired for a period of time, also. This allows them to travel for half the year and rent their home to someone who can take care of their yard. The possibilities are endless. 

At first, they hoped for their own private space. But, the high cost of construction meant they need to have more renters in the space than originally planned. 

“We wanted to do it where we didn’t have to rent it out,” Springer said, standing in the ADU’s driveway. “Taxes shot up a couple of times and the COVID stuff happened so now suddenly it’s suddenly becoming a strategy where we’re going to need to rent this out to get some income going here.”

Easing regulations opened more interest

The Springers are one of a growing number of Bosieans choosing to build separate living units called ADUs on their property, either for rent long-term, short-term or to other family members. Last June, the City of Boise loosened restrictions on the structures to make them easier to build larger and easing parking restrictions in some instances. In that time, a higher number than ever before applied for building permits to construct them. 

Between June 1, 2018 and June 1, 2019, before the regulations changed, the city of Boise approved 33 ADUs. But between June 2, 2019 and early October, the city approved 94 units. To compare, the city permitted 143 ADUs in the decade between 2008 and 2018. 

The city’s hope for changing the ordinance was to create more dense, affordable housing throughout Boise by tucking it into existing neighborhoods. The changes allowed ADUs to be up to 700 square feet and include a second bedroom so a small family could live there. It also waived the requirement for a parking space for ADUs with only one bedroom. 

Originally, the city proposed eliminating the regulation requiring the owner to live on the property instead of renting out both the ADU and the home. After strong neighborhood opposition, the city council scrapped the provision, meaning an owner must still live on site.

[All about ADUs: After tweak to law, ‘granny units’ gain popularity in Boise]

Low impact housing

Susan Eastlake, a former ACHD commissioner, is one of the founding members of a group raising awareness for ADUs and encouraging Boiseans to build them as an affordable housing solution. She said the group hasn’t made any policy recommendations to the city yet on how they can be more easily accessible, but Eastlake said they are important for housing working class Boiseans. 

“We’re talking about the young professionals,” Eastlake, spokeswoman for ADU Simplified, said. “The young people who want to be police officers in the city, teachers in the city, as well as the retail sector, where people are not making the salaries where they can afford to live in houses in Boise.”

It is unknown how many of the ADUs are being used for short-term rentals on sites like Airbnb instead of for long term residents of the city. The State of Idaho places limitations on how cities can regulate these types of rentals, and the city does not track them.

Boise’s Deputy Director of Current Planning Cody Riddle said most of the ADUs approved so far have been in some of the city’s older neighborhoods with alley access making them more conducive to a smaller residence on a property. He said the city sees positive signs in the early number of applications.

“Obviously 94 ADUs is just scratching the surface, but they’re exclusively infill,” he said. “They’re typically close to services that are already present and they don’t require us to expand infrastructure. It’s very low impact housing.”

Springer knew from the beginning when her family built an ADU they did not want it to use it for long-term rentals. They wanted the unit to remain furnished to prevent the possibility of damage when renters move furniture in and out of the unit. They were concerned about sharing their space with another person for a long period of time that could disrupt their neighborhood. 

“It’s the idea when you’re a homeowner and you love your house and you love your neighborhood and you want to be a good neighbor, to have somebody come in and be an unknown quantity, potentially with loud parties…,” she said, trailing off. “You don’t know who this person is going to be, and then this person becomes part of our overall situation so close to us.”

Sticker shock

Builders have seen an uptick in inquiries from homeowners wondering about constructing ADUs. Joe Levitch, owner of Levco Builders and a member of Eastlake’s group, said he gets regular calls to build the units. He also owns one himself, which includes a shop and an apartment on top. He said the rent cost from the long-term renter pays for the costs of building the structure. 

But, he said many people who come to him hoping to build an ADU have sticker shock. Depending on the size of the building, accessories and if it includes a garage or not, he said the cost can range from $150,000 and to up to $220,000. 

“It seems expensive per square foot, but the reality is it’s an expensive structure to build because it has very little square footage and a lot of expensive components within it,” he said. 

The city also charges impact fees for ADUs because they are separate structures. Levitch said elsewhere in the country cities and counties waive these fees to encourage more homeowners to build them and provide housing. He hopes Boise will take this step, but there has been no talks of this at the city so far. 

Springer’s ADU also was a case of sticker shock. She said the final product ended up exceeding their budget by 250%. Springer did not have the final total available, but she said the project exceeded $100,000 by the time they had barely finished framing the structure. Because of the high cost, she said they are now looking at renting out the space more than they were before to pay for the cost. They also plan to refinance and take advantage of lower interest rates to make the project more affordable after blowing past their budget. 

Through word of mouth, Springer connected with a student to rent to who plans to study in Boise for about six months. Springer said because she wants to provide a more affordable option and help out the student she will rent the studio for $1,300 per month, but through her research she found the market would allow her and her husband to rent the space for up to $1,800 per month for long term stays. Both of these rates are far above the median rent for Boise of $1,020, according to a study from released earlier this month.

“Doing market research, what it looked like we should be able to rent this thing for are prices that didn’t sound and feel affordable,” she said. “But, we dropped this for (the student). We want to do something with this that matters and does some good.”

Margaret Carmel - BoiseDev Sr. Reporter
Margaret Carmel - BoiseDev Sr. Reporter
Margaret Carmel is a BoiseDev reporter focused on the City of Boise, housing, homelessness and growth. Contact her at [email protected] or by phone at (757)705-8066.

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