Time to Add a Guesthouse

In response to housing shortages in big cities, states are making it easier for you to build an accessory dwelling unit (or ADU-a stand-alone living structure on the same property as your main house). Here's how to plan for one.

- Kaitlin Petersen

Know the Rules

First step: Check your state and city zoning laws, as well as with your homeowners’ association if you have one. The ordinances will help you understand what ADUs are possible to build on your lot: one additional apartment? One structure with two units? (The latter could double your return on investment if you rent it out.) The planning stage is a great time to bring in an architect or designer who is well-versed in local codes and requirements. Since ADUs are, by definition, for dwelling, they must include heating, a bed room, a full bathroom, a small kitchen with a cook top and  refrigerator, and a separate  entrance. “A lot of my clients want a separate unit for their parents, but they think their parents will use the kitchen in the main house,” says Mary Maydan, principal of Maydan Architects in Palo Alto, California. “You still have to build a small kitchen.”

Do consider luxe finishes. “Even if you go crazy on the tile, there’s only 25 square feet of it,” says Matt Hutchins, principal of Seattle-based CAST Architecture. “It’s really easy to make [these spaces] special.”

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