Mar West sits above the San Francisco Bay in Tiburon. The waterfront and the hillside are inseparable here. The views are wide open, and water and light create an atmosphere that feels alive. The neighborhood rises quickly from the waterfront and the slope that the house sits on is the defining constraint of this site. It demands working with what’s here rather than forcing something onto it.
The original owners were Peter Berg, a Cal Poly architecture graduate and a founding member of Gensler, and his wife. That context helps explain the home’s mid century sensibility and its restraint on a site that could easily lean into spectacle. The house has always prioritized proportion, simplicity, and connection to its setting. Those same principles are guiding how the project is being carried forward today.
Kasten Builders has been working toward this moment for months. Early pre-construction planning helped move permitting forward on an accelerated timeline and ensured key decisions were made before work began on site.
The design team is led by Sean Bailey Design, also a Cal Poly graduate, with support from key partners including The Scale Collective, Studio Green, GFDS Engineers, and CMH Integrated. This collaboration has been as defining as the site itself, setting the project up for a smooth start.
At times, the home has felt like a treehouse to the current owners. They want more space, better flow, and a more grounded experience. This remodel will expand the home into a modern, multi level residence that feels more settled into the hillside, while preserving the calm, restrained character that made the original compelling.
Inside, demolition is underway. Walls and assemblies have been opened up so the team can confirm existing conditions and prepare for the structural work ahead. The goal is to expose what needs to be seen, protect what stays, and clear space for what changes.
Outside, preparations are underway for the new foundation. The process begins with removal of the existing driveway slab, which clears the space needed to install temporary shoring to support the existing structure. From there, the hillside will be stabilized, enabling deeper excavation for the new lower levels, including the garage and ADU.
This is a moment when the scale of the project becomes easy to understand. The excavator is the obvious part. The real work is the careful approach behind it. Kasten Builders has prepared for this phase so the first days on site could move with control and intention. It’s a reminder that a strong start isn’t loud. It’s measured, coordinated, and done with care.
A lot of people have contributed to getting Mar West to this point. The early work has been executed with precision, and the team has set a strong tone for what comes next. Follow along as we share progress through the next phases, documenting key milestones and the people behind them.
