Looking for the missing middle housing

Middle housing can be a more affordable route to ownership—where it exists

“Middle” housing refers to a range of housing types–from duplexes to townhomes to low-rise multifamily developments–that bridge a gap between single-family housing and more intense multifamily housing.

Middle-density housing can help promote more affordable ownership options, give people greater housing choices and produce densities that support walkable communities.

Yet this housing option is few and far in between in many communities, hence the term “missing” middle-density housing.

In this blog post, part two of a series about housing data from the Regional Housing Needs Assessment, we look at the landscape of this housing in the region, whether they’re for sale or rent, and where they’re being built.

PSRC previously delved into the cost of middle-density housing. In short, while it makes up a relatively small share of the market, this type of housing tends to be more affordable than lower- or high-density ownership options.

Single-family homes are the most common housing type in the region

Single-family homes make up 59% of the region’s 1.7 million housing units.

In Kitsap County, detached single-family homes make up the largest percentage of the overall housing stock (72%).

On the other hand, King County has the region’s lowest share of single-family (53%) and a significantly larger stock of low-density and high-density multifamily homes.

Kitsap, Pierce and Snohomish counties provide relatively more small-scale multifamily buildings as opposed to the larger (20 or more units) multifamily buildings.

Most middle-density housing is in the rental market

Middle-density housing can provide more affordable ownership options, but 76% of this housing is renter-occupied. Overall, 42% of the region’s rental stock is made up of middle housing.

Ownership housing is dominated by traditional detached single-family housing (84% of all units). Only 9% of the region’s ownership stock is middle housing.

Building trends for middle-density housing are different for rentals than for ownership stock.

Construction of middle housing for the rental market peaked during the 1980s and has been dropping off steadily since then. Production of middle-density ownership housing, on the other hand, increased steadily through the 2000s, then dropped off noticeably during the current decade.

Middle-density zoning has produced a mix of units

Where this type of housing is allowed, what gets built? We looked at residential zoning across the region and identified areas that allowed 10 to 49 units per acre.

From 2010 to 2018, about 34,100 total units were permitted in areas zoned for middle-density development. This accounts for about 18% of residential permits in the region. Two-thirds (23,200) of those units were multifamily. These zones did result in a fair amount of new single-family development as well (10,900 units). The majority of these units were permitted in King County, specifically Seattle.

The Regional Housing Needs Assessment covers this topic and a lot more data about housing trends in the region. This analysis will help support development of the Regional Housing Strategy.

Our final part of this three-part series, about housing supply, will be published soon. In part one, we looked at cost-burdened households.

PSRC’s Housing Innovations Program provides more information about developing middle-density housing.