At 2,200 square feet and three floors, Barry and Candice Peterson’s floating residence— designed by architect Tim Carlander—is large by houseboat standards and boasts nearly 900 square feet of outdoor living space, including a generous rooftop deck reached by a spiral staircase from the upper, public floor. Bedrooms, encased in glass, are at the water level; there’s even a full basement for storage belowdecks.