Boise Population Growth: The Housing Analysis relied on Census data to determine population growth from 2010 to 2019, which includes the annual American Community Survey updates of the decennial census count. During that decade, Boise City saw an average 1% growth per year, including a 0.8% growth from 2018 to 2019. Ada County saw an average 2% growth, including a 2.36% growth from 2018 to 2019.

Accordingly, the Boise Housing Analysis assumed that a 1% population growth in the City of Boise would continue for the next decade.

The analysis only looked at Ada County and did not consider migration patterns with other counties. It is well-understood that housing is a regional issue and that households will make decisions based on affordability, even if that means traveling across county lines.

The Work of Others: We conducted a literature review of available data for Ada County and City of Boise as it related to housing, demographics, and special populations like people experiencing homelessness, students, refugees, and seniors. COMPASS provided a demographics report (Demographics Quick Guide – July 2019) that acted as quality assurance for projections using Census data. A separate study on the Boise Area of Impact estimated that the housing need for additional housing units by 2025 would be 2,366 units per year. Data points like these offered a test of the assumptions in this study.

To understand the current market’s delivery of housing units, the analysis used COMPASS’ open-sourced data on building permits to estimate the number of units coming online in the last few years. This allowed a comparison of the housing need compared to the current delivery of newly constructed units.

Methods: When considering how to estimate housing demand, we considered past approaches (including Agnew::Beck’s own study in 2014 for the Boise Housing Needs Analysis). Our conclusion was that housing studies did well in considering how population growth (or retraction) impacts housing need over time. These studies also understood churn – housing units being taken off the market through disrepair or other methods. It was concluded that a majority of housing studies were missing other important characteristics that impact need for housing units and information for policy makers.

Specifically, the analysis looked at the following characteristics to influence housing demand:

Definition of Terms

Population Growth

Using population rates over the last decade, estimate housing need based on population growth rates projected out 10 years. Also, the estimate includes the units needed to achieve a 5% vacancy rate, which is considered a healthy housing market.

Data source: U.S. Census and American Community Survey

Poor Condition

Some housing units will require replacement in the coming decade due to several factors. Three factors, tracked in Census data, provided perspective to this study:

(1) Units without plumbing and kitchen facilities (1.3% of the Boise market); (2) Units built before 1949 (10.6% of the Boise market); )3) Mobile home units (3.9% of the Boise market). The study assumed that only a small portion of these units will need to be replaced (1,430 units over 10 years).

Data source: U.S. Census and American Community Survey

Severe Overcrowding

In today’s market, there are housing units that have multiple households crowded into one housing unit. This creates an unhealthy condition for those households. Census data tracks the number of people per bedroom, which allows for an estimate of crowded housing units, defined by more than 1.5 people per bedroom on average. Data suggests that 1% of Boise units are overcrowded. The study assumed then that 1% of new units are needed to overcome the overcrowding and provide adequate housing for the number
of households in the market.

Data source: U.S. Census and American Community Survey


Some households in every jurisdiction do not have homes; the current housing market is not serving them. Also, the U.S. Census traditionally underreports people experiencing homelessness, due to the barriers in reaching this population. Accordingly, the study relied on estimates from the Homeless Management Information System to estimate the population without housing. And then, through interviews with the Corporation for Supportive Housing and Our Path Home providers, estimated that 30% of the homeless population was not counted in our Census estimates.

Data source: Homeless Management Information System and Key Informant Interviews

Cost-Burdened Households

43% of Boise households are paying more than 30% of their income on housing costs, with 36% of households paying more than 35% of their income. This demonstrates an unhealthy housing market. The analysis considered that the demand for housing was not equally distributed across all income levels. Specifically, the need for future housing units skews drastically toward the need to overcome the 43% of households who are paying too much for housing. Those households are significantly more likely to be lower-income households. If the market produced as many housing units as were needed for the population growth, but those units were all serving those above 100% of the area median income, then the % of households who are cost-burdened would stay the same, if not increase. To overcome this need, the study suggests the production of affordable housing units that will address the cost-burdened households.

Data source: U.S. Census and American Community Survey

Area Median Income

The income that the median household makes, meaning that 50% of households of the same size earn less than the median household and 50% of households earn more than the median household. The median income changes based on household size.

Supportive Housing

A type of affordable housing that is primarily targeted to an extremely low-income population and has a need for supportive services. This housing combines affordable housing with dedicated supportive services either delivered on-site or off-site of the property. Supportive housing primarily serves households exiting homelessness.

Affordable Housing

By housing unit: Any housing unit that has a rent or mortgage that is affordable to a household earning less than 80% of the area median income. Often the property will include a government subsidy, either for the capital costs or to assist with the rent. There could be a need for dedicating supportive services to the property, depending on the population housed.

By household: Housing is considered affordable to a household if they are paying 30% or less of their income to housing (either rent or mortgage).

Workforce Housing

A type of housing targeted for those earning between 80% and 120% of the area median income. This housing is meant for our “workforce” but can be a misleading term. With stagnant wages, “workforce housing” is better thought of as a type of market-rate housing, because it is largely unaffordable to much of the service-based workforce. In the following slides, the term “market-rate housing” refers to both “market rate” and “workforce.”

Market Rate Housing

Any housing that has a rent or mortgage that is only affordable to those earning the median wage and above. There are no rent restrictions on the property and often no government subsidies.

Cost-Burdened Household

Any household who is paying more than 30% of their income for housing.

Gap Financing

The amount of financing needed to fully fund the development of a housing project after the primary sources have been identified and secured.

List of Sources

Message Sent Successfully!

Message Failed To Send.

Send a Message to City of Boise

Please fill out the form and a representative from the City of Boise will be in touch with you.