Missing Middle Housing

What Is Missing Middle Housing?

Missing middle housing is the group of building types that sit between a detached single-family house and a mid-rise apartment building. Daniel Parolek, founder of the architecture firm Opticos Design, coined the phrase in 2010. He used it for multi-unit or clustered housing types that are compatible in scale with detached single-family homes. Typical types include:

• Duplexes, triplexes and fourplexes
• Townhouses
• Cottage courts, meaning small detached homes around a shared yard
• Courtyard buildings and small multiplexes
• Live-work units

“Middle” describes the building’s scale, which falls between a house and an apartment block. The label does not mean a home is reserved for middle-income households or carries any income restriction.

How It Works

The key design idea is that a building holds several homes but is no bigger than a large house. Opticos lists the typical features as a small building footprint, fewer off-street parking spaces, simple wood-frame construction, and a walkable location.

These buildings are “missing” because, in many places, zoning no longer allows them. Oregon’s land-use agency notes that such homes were long built in its cities before being outlawed. Many 20th-century zoning codes reserved most residential land for detached single-family homes. Minimum lot sizes and parking requirements can also make small multi-unit buildings hard to fit on a typical lot.

Some states have begun to change that:

• Oregon, House Bill 2001 (2019). Medium-sized cities, meaning those of 10,000 to 25,000 people outside the Portland metro area, had to allow duplexes in areas zoned for single-family homes by June 30, 2021. Cities over 25,000 and cities in the Portland metro area had to allow duplexes, triplexes, fourplexes, cottage clusters and townhouses in residential areas by June 30, 2022.
• Washington, House Bill 1110 (2023). Covered cities must allow from two to six homes per lot in mostly residential zones. The number depends on the city’s population, how close the lot is to a major transit stop, and whether some of the homes are affordable. Cities of 25,000 or more must allow at least six of the nine middle housing types named in state law. The deadline is six months after each city’s next periodic comprehensive plan update is due.

Why It Matters for Workforce Housing

Smaller homes on shared land can cost less to buy or rent than a detached house in the same neighborhood. That can put them within reach of teachers, nurses and other moderate-income households, the group that workforce housing is meant to serve.

Criticisms and Limitations

Legalizing a building type does not guarantee it will be built. Oregon’s own agency expected change to come gradually and to depend on local housing markets. Land, construction and financing costs still apply. Middle housing built at market rate is usually not income-restricted, so it may cost less than nearby houses without being affordable in the subsidized sense. Washington’s MRSC notes, for example, that many townhouses are not affordable to households earning less than 80% of area median income. Some residents oppose middle housing as a change to neighborhood character.