A traditional home in the Claremont Hills of Berkeley is enlarged and fully renovated to fit the lives of a young couple and their growing family. The existing partial upper floor was fully expanded to create three additional bedrooms, a hall bath, laundry room and updated master suite, with the intention that the expanded house volume harmoniously integrates with the architectural character of the existing home. A new central staircase brings in a tremendous amount of daylight to the heart of the ground floor while also providing a strong visual connection between the floors. The new stair includes access to an expanded basement level with storage and recreation spaces for the family. Main level spaces were also extensively upgraded with the help of noted San Francisco interior designer Grant K. Gibson. Photos by Kathryn MacDonald.