Both ADU bills passed. Now it's Newsom's call

Ten days ago I wrote that the two ADU bills worth watching had to clear the Legislature by August 31 or die. Both cleared. Neither is law yet.

If you've been holding a decision on a backyard project, this is the update, and the honest version of it is that you're now waiting on one person instead of 120.

What happened in the last week of session

SB 1117 moved first. The Assembly's amendments were concurred in on August 25 by a vote of 38 to 0, and the bill was enrolled and presented to the Governor at 6 p.m. on August 30. It's sitting on his desk right now.

AB 956 took two more days. The Assembly concurred in the Senate's amendments on August 27 by 60 to 2, and it went to engrossing and enrolling, which is the clerical step before it reaches the Governor.

Sixty to two, and thirty-eight to nothing. Neither of these was a fight. That's worth holding onto when you read anything dramatic about the housing package this year, because these particular bills passed with almost nobody objecting.

What each one does, briefly

AB 956 raises the number of detached ADUs you can build on a single-family lot from one to two. It also bars homeowners associations from blocking an ADU that complies with state law, and it clears up the zoning language that some cities have used to deny ADUs on single-family houses sitting on multi-family-zoned parcels.

SB 1117 is narrower and, for a lot of owners, worth more money. Today, ADUs of 750 square feet or less are exempt from impact fees, and anything larger can be charged proportionally against the primary dwelling. SB 1117 changes the math so cities can only charge on the square footage above 750. Build a 1,000-square-foot unit and your fee base drops from 1,000 feet to 250.

The part that isn't done

The Governor has until September 30 to sign or veto. Bills enacted on or before October 2 take effect January 1, 2027.

So nothing about your fall changes. A permit application you file in October gets reviewed under today's rules, with today's fee schedule and today's one-detached-unit limit. The earliest either bill helps you is a January filing.

I want to be careful not to oversell the odds here. A 60-2 vote tells you the Legislature liked it. It doesn't tell you what the Governor does, and bills with big margins do get vetoed, usually over cost or over some interaction with another law that never came up on the floor. I'd put both of these in the likely-signed category and I wouldn't bet a project on it.

What to do with September

If you were already planning a build, keep planning. Nothing here should change your timeline, only your drawings.

The one concrete thing worth doing is talking to your architect about a site plan that works with one detached unit and can accommodate a second later. If AB 956 gets signed, you file in January with an option you didn't have in August. If it gets vetoed, you build the unit you were always going to build. That flexibility costs very little at the drawing stage and a great deal after you've poured a foundation.

On the fee side, pull your city's impact fee schedule now if you haven't. SB 1117 only matters to you in proportion to what your city charges, and that number varies enormously across Santa Clara and San Mateo counties. Some cities already waive or defer ADU fees on their own, in which case the bill is a non-event for you. Others will hand you a five-figure number for a 1,000-square-foot unit, and there the bill is the whole ballgame.

If you're in an HOA, this is the month to read your CC&Rs properly. A signature on AB 956 makes a chunk of that language unenforceable against a compliant ADU, and it's better to know now which clauses you're about to stop worrying about than to discover it during a design review. The HOA litigation has been going the other direction case by case, and a statute settles faster than a published opinion.

For owners who aren't building

If you already have an ADU and you're renting it, none of this touches you in the near term. More legal backyard units eventually means more competition, but that's a 2028 and beyond question and I wouldn't reprice anything over it. Your permit timeline and your tenant are unaffected either way.

The one group that should pay attention is owners sitting on a large lot who've assumed one unit was their ceiling. If AB 956 is signed, the ceiling moves, and the arithmetic on a second unit is different from the arithmetic on the first: you've already got the utility work, the access, and the site knowledge. The second unit is usually cheaper per square foot than the first one was.

I'll write this up again when the Governor acts. Until then, September is a month for drawings and fee schedules, not for permits.

Thinking about a second unit, or want to know what your existing ADU should be renting for? Get a free ADU rental analysis and I'll go through the numbers for your property. Or call me at (408) 813-8001.

Sources

• AB 956 bill history — California Legislative Information
• SB 1117 bill history — California Legislative Information
• AB 956: Double Detached ADUs — California YIMBY
• SB 1117: Reducing the Cost of ADUs — California YIMBY
• 2026 Tentative Legislative Calendar — California State Senate
• A raft of California housing bills heads to Newsom — HousingWire