The Challenge: These San Francisco homeowners wanted to expand a very small underground garage beneath their Victorian home to allow room for parking multiple vehicles. They also wanted to avoid having to back up to enter the street, and they asked that the garage be made moisture proof to provide additional storage. The excavation and construction work had to be accomplished without disturbing recently renovated buildings on either side that had foundations adjacent to our project’s foundation.

Our Solution: We assisted the structural engineers with the technical aspects of the design and then constructed a 2500 square-foot underground garage for the historic Victorian home. The centerpiece of the garage was a turntable large enough for a car, which allowed the homeowners to turn their cars around inside the garage and then enter the street while driving forward.

We shored the building with steel columns & beamson drilled piers. Lateral shoring was accomplished with soldier pile and lagging, protecting the adjacent properties and their foundation. During excavation we confronted underground springs that needed to be diverted and the site dewatered.

An advanced moisture barrier and sophisticated drainage system encapsulated the concrete floor and walls to ensure total moisture control.

A high-tech membrane was placed around the entire underground structure to ensure moisture control. New concrete retaining walls were built, and an elevator shaft was added to allow the homeowners to enter the house without going outdoors. After the garage was finished, the homeowners added closets along both sides so that they could store clothing and other valuables.

To discuss your underground garage project, please contact SteelCore Builders at: 415-331-0525.