In 1990 they hired Robert Oshatz to design an addition and completely new, non-traditional exterior appearance for their home. They wanted stucco to be the predominant material, for its durability and appearance. The roof slope of the addition matches the slope of the original house. The Williams' were fond of circles and they became a theme of the design. The south side of the second-story is glazed with semi-circular disk-like fins at vertical mullions, providing privacy from the street.
The original garage was removed and a three-car garage added. A new laundry room was added, and the existing family room was enlarged in the same area. The kitchen was removed and a new kitchen was created within an airy and light filled part of the existing south deck. A staircase was added for more private circulation. A second floor playroom was added over the garage and the small adjacent child's bedroom was enlarged to the northwest with the use of a semi-circular form in section. Phase 2 added a master bedroom suite.