State laws that allow additional homes: Affordable Housing Density Bonus 🏠 Up to 100% more units if some are for low/middle income Accessory Dwelling Unit (ADU) law 🏠 Existing building can increase number of units by up to 25% by converting garages, storage, etc. 🏠 Can add up to 8 detached ADUs 3/
For details: California Density Bonus law leginfo.legislature.ca.gov/faces/codes_... California ADU handbook www.hcd.ca.gov/policy-and-r... 4/
Of course, not everyone will build to the maximum density. There's no requirement to do anything at all, people are free to keep their house as-is as a single family house. In other cases, a lower-density development may make more sense personally or financially. Let's look at some examples. 5/
Many Backyard Apartments already exist in Berkeley, built before the 1970s downzone. This design works well on deeper lots where the existing building already has someone living in it, whether it's a homeowner who wants to stay, or tenants, who have protections under Berkeley law. 6/
With 3 stories allowed under the Middle Housing zoning (which is also the maximum height allowed before 2 stairs are required by the building code), a backyard apartment building easily fit 3 two-bedroom homes, or up to 6 studio apartments. 7/
The Double Duplex is a type of housing in Los Angeles that could become common in Berkeley also. Popular with students and other singles, each bedroom suite has its own bath and is rented separately. Since each building only has two kitchens, it can be built using the simpler Residential Code. 8/
Why this and not a single 6-8 unit apartment building?
IRC vs. IBC, and all of the related threshold regulatory issues that crop up when you move from the land of single-family-ish houses to apartment buildings
So the threshold is two units per building? And units of course are defined by kitchens and kitchens by stoves and stoves by gas hookups or stove outlets? Are we gonna be seeing a lot of “wet bars”?
Yes, maximum of two units for Residential Code. In the US, dwelling unit = stove, leading to the saying that zoning is about stove quotas.
Cool, I have officially coined a saying!
Rooming houses and other group housing with up to 16 occupants are also allowed under the Residential Code.
Many single-house examples already exist in Berkeley. A type of group living, they're also known as Co-Living, Mini-Dorms, or simply living in a house with roommates. I've written more about Double Duplexes here, with some example floorplans ordinaryhomes.blogspot.com/2023/07/doub... 9/
The latest on Double Duplexes in this article by @henrygrabar.bsky.social. They're common in Los Angeles, especially near the University of $outhern California, where most students live off-campus. bsky.app/profile/henr...
thank you for spelling the school's name correctly
Cal taught me well 😂🐻
Another Double Duplex article, this one from @futureis.la bsky.app/profile/futu...
Lots of academic and general interest articles written about Double Duplexes - does anyone know if there's an article that follows more the format of a business plan, with timeline, cost calculations, etc? If not I might write one.
Since most new homes built in Berkeley are rental apartments, there's a shortage of homes for sale. As a result, townhouses are likely to be popular under Middle Housing. Using state law SB684/SB1123, a lot can be subdivided so that each townhouse is on its own piece of land. 10/
Known as Small Lot Subdivisions in Los Angeles, this type of townhouse project is becoming popular in Silicon Valley as well. Parking is hard to fit on a 50-foot wide lot, however, if two lots are combined, it's easier to do a shared driveway. ordinaryhomes.blogspot.com/2023/11/slot... 11/
The 8+8+2 maximizes the number of homes without needing the Density Bonus or going to mid-rise construction. In Phase 1, an 8-unit building with extra storage space is built. Phase 2 converts the extra space into 2 ADUs, adds 8 ADUs in a 2nd building. Mostly studios & 1-bedroom apartments. 12/
The Density Bonus project has slightly more homes than the 8+8+2, and these homes are also larger - this example has two-bedroom and three-bedroom apartments. To get the maximum bonus using state law AB 1287, both low income & moderate income units are included. Roof deck provides open space. 13/
Shared driveways: Silicon Valley's forced communal living hack.
Any adjustment to the maximum lot coverage rules?
Lot coverage is 60% max, which is close to what's physically possible after subtracting the required yards. Both the lot coverage and yard regulations can be waived if a project provides low or middle income housing for a density bonus.
is hardscape still included in lot coverage, or exempted now?
Lot coverage only includes buildings. Outdoor walkways, patios, etc are excluded.
That's good to hear. Was pretty sure hardscape was included last time I read the code, but that was years ago.
Here is the current definition of lot coverage in Berkeley. Only decks, porches, etc that have a roof over them count towards lot coverage. First 800 sq ft of ADUs is also exempt (per lot, not per ADU) berkeley.municipal.codes/BMC/23.106.020