Half the Floor Plan Is Outdoors at This Off-Grid Prefab in Washington

Welcome to Prefab Profiles, an ongoing series of interviews with people transforming how we build houses. From prefab tiny houses and modular cabin kits to entire homes ready to ship, their projects represent some of the best ideas in the industry. Do you know a prefab brand that should be on our radar? Get in touch!

Matt Wittman could have been a farmer, having grown up in ranching country in Eastern Washington and Idaho. Instead, he became an architect, but held onto a respect for the utilitarian buildings that defined his childhood. He now combines a reverence for those function-first structures with a modernist ethos, which is a through line at Wittman Estes, the architecture and landscape design firm he cofounded in Seattle in 2012.

Today, the studio is building on early early prefab experiments like a fire station and a solar-power studio with its first modular home concept, Puzzle Prefab. The building system allows for endless custom arrangements, says Wittman, the flexibility a means of minimizing a project’s impact on the surrounding environment while connecting its inhabitants to it as much as possible.

On the heels of the first completed Puzzle Prefab on Whidbey Island in Washington, we chatted with Matt Wittman about the pilot project and how it can reshape how we think about building sustainably.

What qualities make Puzzle Prefab stand apart from other prefab homes?

While prefab houses are sometimes divorced from their context, Puzzle Prefab can be modified according to each site; we can make an infinite variety of shapes and arrangements. This system has the ability to create spaces that can expand or contract for a variety of environments, whether remote, suburban, or urban.

How does the Whidbey Island home take advantage of the building system?

A footprint of 600 square feet of living spaces open out to 557 square feet of covered outdoor spaces. This is nearly a 1:1 ratio of indoor and outdoor space. The temperate climate of the Pacific Northwest enables these outdoor spaces to be an expansion of the interior, which gets the owners closer to nature. This size was determined as "just enough" for the client’s family needs.

How does your construction and installation method minimize impact to a project site?

Much of the construction of the Whidbey Puzzle Prefab happened off-site. The pin foundation system we use meant that there was minimal disturbance and digging in the forest ecology where the home now stands. Hand-set pins reduce site disturbance, so we were able to protect tree roots and reduce the home’s carbon footprint by 77 percent relative to a concrete foundation.

Does the home have additional sustainability features?

The home’s steel columns are structural while also acting as downspouts. Water is stored in a rainwater tank and purified with a custom filtration system, making rainwater safe for use in kitchens, bathrooms, showers, and washing machines, as well as indoor greenhouse irrigation. A 4.1-kW solar array drives a heat pump with hydronic heating and cooling and energy recovery ventilation. Smart-home controls monitor energy use to help residents align heating, cooling, lighting, and ventilation to their comfort.