Lincoln
San Anselmo, California
Lincoln is a useful case study because it sits just outside the clean ministerial path. The project has the basic logic of an SB 9 lot split: one residential parcel becoming two homesites, with a new single-family home added behind or beside the existing house. But because a back corner of the property falls within a flood zone, the project is disqualified from SB 9 eligibility and must proceed through San Anselmo’s conventional approval process instead. That makes the project a good example of how state housing law can still influence design and development strategy, even when a site-specific constraint prevents the project from using the statute directly. SB 9 provides the conceptual model; the conventional entitlement process becomes the actual path.
The home showcases some of our signature design features: the entryway unfolds into a spacious, open living and dining area, with abundant natural light from the south-facing windows.
Details
- 1,600 exterior square feet
- Two-story layout
- Three bedroom, two-bathroom
- Full-size built-in kitchen
- Large attached balcony
Lincoln is a conventional approval project shaped by an SB 9 idea. The site has the physical characteristics of a promising urban lot split, but a flood-zone condition prevents use of the ministerial SB 9 pathway. Rather than abandoning the opportunity, the project carries the SB 9 logic into a traditional entitlement process: split the lot, preserve the existing home, and add a new three-bedroom single-family residence.
The policy story is about the limits of ministerial legislation when environmental constraints are present. The human story is about a young family creating a more functional home while turning their existing house into rental housing. Together, the project illustrates how small-scale infill can be both legally complex and highly practical.
Lincoln begins as the type of infill opportunity that SB 9 was intended to reveal: an existing residential parcel with enough land area to support a second independent homesite. Under an ideal SB 9 scenario, the project could have pursued a ministerial urban lot split and created a new parcel for an additional primary residence.
The constraint is that the site is not legally clean. A back corner of the property falls within a flood zone, which disqualifies the parcel from the SB 9 pathway. Instead of a streamlined ministerial approval, the project must move through San Anselmo’s conventional planning and subdivision process.
The case study is not simply about losing SB 9 eligibility. It is about how SB 9 changes the way a site is evaluated. The law establishes a new baseline assumption: many single-family lots have latent housing capacity. Even when the statute cannot be used directly, it can still clarify what a reasonable infill outcome might look like.
For Lincoln, that means pursuing a conventional lot split and a new three-bedroom single-family home, using the design logic of SB 9 as a reference point. The project tests whether a modest, context-sensitive new home can be added to an existing residential property through traditional approvals, while still reflecting the housing policy direction established by state law.
The client story is direct and relatable: a young family has outgrown their existing house. They spend part of the year in Korea and need a home that better supports their family life when they are in San Anselmo. Rather than selling the property and competing for a larger home elsewhere, they are using the land they already own to create a better long-term housing arrangement.
The proposed new three-bedroom home becomes the family’s primary residence. The existing house remains on the original property and can be rented out, creating income and making the overall project more financially durable.
This is the kind of incremental infill that is often missing from the housing conversation. The project does not require demolition of the existing home. It does not replace one household with a much larger building. Instead, it adds one new family-sized home to an established neighborhood while preserving the existing house as rental housing.
The use case also reflects a more flexible version of homeownership. The family’s life is partly local and partly international. Their housing needs are not static. Lincoln allows the property to adapt: one home for the owners, one home for renters, and a lot configuration that creates
