A Seattle Magazine Essential: The Parametric Casita
ORIGINALLY APPEARED IN SEATTLE BUSINESS MAGAZINE ON FEBRURARY 5, 2021.
BY SEATTLE MAGAZINE STAFF
Exterior rendering of Parametric Casita / Render by JA
Property owners who want to add detached dwelling units in Seattle’s single-family housing zones can use Johnston’s technology — which it has dubbed “Parametric Casita” — to input their address and discover the developable area on a single-family lot. Clients can then choose from predesigned modules to design their own detached accessory dwelling unit. The site is still in beta mode, but will undergo a significant upgrade this month.
Mayor Jenny Durkan last year signed one of the nation’s least-restrictive ordinances to reduce permitting times and costs for homeowners seeking to build accessory dwelling units. The city also launched a website, ADUniverse, featuring pre-approved city permits for cottage designs.
Johnston Architects offers a simplified structural model and provides rough construction costs.
Johnston Architects Partner Jack Chaffin says the Parametric Casita site has the ability to give clients customized plans and documents rather than a “one-size-fits-all” method. He says a coworker recently built a dwelling in her backyard and the city’s permitting process took just two weeks.
“One of the reasons we started exploring this, in general, is that clients have been asking us to build these small houses,” he says. “In the past, we’ve done small houses, but they’ve been in more rural and resort areas, not in an urban environment, too.”