Five-over-one

Five-over-one describes a building with up to five stories of light wood framing stacked on a one-story concrete podium, which usually holds parking, retail, or lobby space. The name comes from building code construction types: the wood upper floors are a lower-cost type, and the concrete podium is a fire-rated type that lets the code treat the two as separate buildings. Variants include four-over-one and, where codes allow, more stories of wood over a two-level podium.

The type is common because it sits at a sweet spot in the cost curve. Wood framing is less expensive per square foot than steel or concrete and can be built by a large pool of contractors. Building codes cap how many stories of wood can be stacked, so the podium lets a developer add one more story of a different material without moving the whole building to a costlier structural system. Above the height that the type allows, the next step is a concrete or steel building, and hard costs per square foot rise sharply.

For housing costs, the five-over-one is the reason so many new apartment buildings look alike, and the reason moderate density is often cheaper per unit than either low density or high density. A zoning code that allows a five-over-one where the market supports it is allowing the least expensive form of multi-family construction; a code that caps height just below it, or that requires more parking than a single podium can hold, pushes projects into a more expensive type or off the drawing board. We compare building types in Why Can't Developers Just Build Cheaper Apartments?.