TBE Architecture is working with Brian Jaffe of the California Cottage Company and Verdant Structural Engineers to prototype a multifamily development template utilizing Senate Bill 9 (SB9) – The California Home Act and Senate Bill 8 (SB8) – the Housing Crisis Act of 2019 to develop projects on existing lots that include a duplex with 2 ADUs that then can be eligible for a lot split. Another notable innovation that Brian is bringing to the project is Compressed Earth Blocks (CEBs). Brian manufactures the blocks locally at the companies’ facility in Rohnert Park.
Some of the benefits of building with CEB include:
• Sustainability: Compressed earth blocks (CEBs) are made from natural, abundant materials such as clay, sand, and water. They require less energy to produce than other types of bricks, and can often be sourced locally, reducing transportation costs and fuel.
• Cost-effective: CEBs are a cost-effective building material that can be used in various applications.
• Energy-efficient: CEBs have insulating properties that can help regulate indoor temperature. They are more comfortable, cooler in the summer and warmer in the winter. They use less energy to modify the temperature when it needs to be modified.
• Adaptability: CEBs are extremely adaptable to nice, complex designs. They’re load bearing, so you can do whatever you want with the walls, with some limitations.
• Low carbon footprint: Building material made from compressed earth has a low carbon footprint.
As for the laws that make these projects possible; SB8 was signed into law in 2022 and allows for the development of duplexes on single-family lots. The bill requires that the lot be zoned for residential use, and that the lot is located in an urbanized area or an urban cluster. The bill also requires that the lot be at least 1,200 square feet in size, and that each unit in the duplex be at least 800 square feet in size. The bill also requires that the units be owner-occupied for at least three years after construction.
SB9 was signed into law in 2021 and allows for the development of up to two ADUs on single-family lots. The bill requires that the lot be zoned for residential use, and that the lot is located in an urbanized area or an urban cluster. The bill also requires that the lot be at least 2,400 square feet in size, or that it has been zoned for residential use for at least three years. The bill also requires that each ADU be no more than 800 square feet in size, or no more than 50% of the existing primary residence, whichever is greater. Additionally, Senate Bill 9 allows for the development of up to four units on a single-family lot if two of those units are ADUs.
Additionally, SB9 allows for the ministerial approval of certain lot splits to allow property owners to construct up to two units on the newly created lots. The legislation permits qualifying lot splits to be approved ministerially (i.e., without discretionary review or hearings) pursuant to a parcel map, upon meeting a number of criteria. The project site must be in a city or urbanized portion of an unincorporated county, and not located on or in any of the following: prime farmland, wetlands, within a very high fire severity zone, a hazardous waste or hazardous list site, within a delineated earthquake fault zone, within a 100-year flood zone, within a floodway, identified for conservation in an adopted natural community conservation plan, habitat for protected species or lands under conservation easement. The project site also cannot require demolition or alteration of any housing if housing is restricted affordable housing, subject to rent control, or contains tenant occupied housing in the last three years. The project site cannot be withdrawn from the rental market (i.e., under the Ellis Act) within the past 15 years. The project does not propose demolition of more than 25 percent of the existing exterior walls unless either the local ordinance allows more demolition, or the site has not been occupied by a tenant in the past three years.
OTHER CALIFORNIA LAWS REGARDING ADUs GENRALLY:
California has several laws that allow for the construction of ADUs on residential lots. One of the most significant laws is Assembly Bill 68 (AB 68), which was signed into law in 2019. AB 68 allows for the construction of up to two ADUs on a single-family lot, regardless of the lot size. The bill also allows for the construction of one junior accessory dwelling unit (JADU) on the same lot, which must be no more than 500 square feet in size and attached to the primary residence. Additionally, AB 68 prohibits local agencies from imposing certain requirements on ADUs, such as minimum lot size and maximum floor area ratio.
Another important law is Senate Bill 13 (SB 13), which was signed into law in 2021. SB 13 requires local governments to approve ADU permits within 60 days of receiving a complete application. The bill also prohibits local agencies from imposing certain requirements on ADUs, such as minimum lot size and maximum floor area ratio.
Civil Engineering by Hogan Land Services
Landscaping by Integra Planning + Landscape
Energy and HVAC by Delta T Energy