SB 9 does end single family zoning in that it allows duplexes to be built on all lots currently zoned for single family housing. I agree that the title should reflect that the linked press release covers three bills: SB 8, 9, and 10, which change many things in California housing policy.

> This bill, among other things, would require a proposed housing development containing no more than 2 residential units within a single-family residential zone to be considered ministerially, without discretionary review or hearing, if the proposed housing development meets certain requirements, including, but not limited to, that the proposed housing development would not require demolition or alteration of housing that is subject to a recorded covenant, ordinance, or law that restricts rents to levels affordable to persons and families of moderate, low, or very low income, that the proposed housing development does not allow for the demolition of more than 25% of the existing exterior structural walls, except as provided, and that the development is not located within a historic district, is not included on the State Historic Resources Inventory, or is not within a site that is legally designated or listed as a city or county landmark or historic property or district.

Source: https://leginfo.legislature.ca.gov/faces/billNavClient.xhtml...

Can the sub lots be subdivided recursively as long as they’re above the minimum 800 sqft dwelling size?

Probably not. Duplexes are attached and usually have one owner.

https://en.wikipedia.org/wiki/Duplex_(building)

They were popular in many cities in the 70s as starter homes. The idea was that you'd buy the whole thing, then rent out one half to help offset your mortgage.

But SB9 also allows lot-splitting if the plot is large enough, right? Also allows duplexes original lot could be x2 and each of those can have one duplex.

Obviously this lot-splitting may not work in areas like Los Altos where each single family lot by city law is required to be 10k sqft or larger (unsure how local laws will interact with SB9).

But question @koolba asks is still valid - can you recursively split large lots into many smaller lots?

> SB 9 does end single family zoning in that it allows duplexes to be built on all lots currently zoned for single family housing

But that's not the same. Ending RH-1 would mean something like "no more RH-1 buildings will be permitted, you must build at least two". Instead, it's "if you have an RH-1 lot, you are allowed to build up to two units".

So I'd say it makes RH-1 also mean RH-2, but doesn't "end" it in the sense most people interpret. (E.g., In San Francisco, you would be unlikely to get planning approval to build a single-family home on an RH-2 zoned lot, because it should have been used for two units).

SB 10 is voluntary; but for the cities that do choose to use it (or selectively use it), now neighbors can’t sue to stop anything 10 units or less from going up based on environmental concerns. It’s big for that reason, where localities would often be sued out the wazoo for environmental concerns for daring to rezone a single family lot as multifamily

SB 9 is paradigm shifting: every lot in California that’s single family zoned can a) be split into two lots of equal size AND/OR b) each resulting lot can now have up to 2 units AND c) if the lot is compliant with all other criteria, each lot is still able to have an ADU built in addition to the extra unit, per statewide ADU law passed two years ago.

So you can potentially turn a single lot into 6 units. Or 3 without splitting the lot. All of this is by-right, too. Design approval and local councils can’t stop it, and I believe they must be approved within 90 days, too.

Your comment is incorrect because you are describing SB 10, not SB 9.

SB 9 indeed allows duplexes on all single-family parcels, as well as lot splits if one of the new homes will be owner-occupied, and neither lot would be less than 40% of the original lot's area.

Ok, we've switched the title. Thanks! Submitted title was "Newsom Signs SB 9 and SB 10, ending single family zoning in California".

Submitters: please don't rewrite titles to make them more misleading. This is in the site guidelines: https://news.ycombinator.com/newsguidelines.html.

See my note: I think "ending" single family zoning is (slightly) misleading given how some municipalities enforce planning and zoning laws. It sounds more impactful than "optionally permits two buildings per site and splitting lots", but without additional change, people can still build single-family homes.

Given that it's generally local governments that are hesitant to upzone, is there any indication of some cities bucking the trend? What barred cities from ending single family zoning prior to these bills?

Previously, if cities did upzone, a neighbor could still sue their neighbor to stop them from building. In places like SF this means every project is tied down for years and hundreds of thousands of dollars of legal fees.

Now, you are effectively not allowed to do that. So the permitting process to build a duplex is as straightforward as the permitting process to build a SFH.

Which, to be clear, is still really hard in most places in CA.

Definitely!

Someone else could explain better but I'm also fairly sure many of the new rules here (such as exempting CEQA) also apply to SFH. They just leave the current rules untouched for commercial/large-scale residential.

The idea with SB10 is that, once the next RHNA cycle starts and cities are required to zone for their share of housing (or face punishment), they will use SB10 as an "easy way out" to upzone while skipping a lot of the usual red tape (CEQA, etc).

Under RHNA and the HAA, if cities fail to zone for their share of housing, many projects will be approved automatically and the city loses its discretionary review authority.