Petaluma's new General Plan has been in effect for about two weeks. It sets the city's direction for the next 25 years. It allows duplexes, triplexes and fourplexes in single-family neighborhoods and sets an eight-story ceiling at the downtown train station. It was adopted on September 14, 2026, after more than five years of public input. Even so, the city's own General Plan page says the zoning code that regulates individual parcels is still being updated. The rule that would let a single-family lot hold up to four homes by right hasn't reached a final City Council vote.
That gap is what matters for this fall. The plan says where the city is headed. The zoning ordinance sets what a particular parcel can hold, and only one piece of that ordinance is close to adoption. If you're comparing two houses at similar prices, that pending rule could make the lots behind them worth very different amounts in a few months.
What took effect in October, and what is still a draft
A general plan works like a city's road map. The City of Petaluma's General Plan page says development projects that need discretionary approval, such as Site Plan and Architectural Review, now have to be consistent with the new plan's densities and policies. The same page says the two codes that actually regulate building are still being rewritten. One is the Implementing Zoning Ordinance, and the other is the SmartCode, which covers the areas around the city's two SMART stations.
The city is doing that rewrite in three phases. The Planning Commission unanimously recommended Phase 1 on October 13, 2026. Its first reading at City Council is tentatively set for November 9, 2026, according to the Petaluma Civic project tracker. The city's project plan targets Phase 2 for June 2027 and puts Phase 3 between December 2027 and March 2028.
| Change | Status as of late October 2026 |
|---|---|
| New General Plan and land-use map | In effect since mid-October |
| Up to four homes by right on qualifying single-family lots | Phase 1; awaiting council, first reading tentatively November 9 |
| New residential parking ratios | Phase 1; awaiting council |
| Citywide Zoning Map applying the new zones | Phase 1; awaiting council |
| Parking cuts tied to transit or nearby amenities | Phase 2, targeted for June 2027 |
| Residential density bonus rewrite | Phase 2; existing chapter stays in force meanwhile |
| Mixed-use corridor standards and transit overlays | Phase 2 |
The four-unit rule, clause by clause
The General Plan's Policy LU-7.2 tells the city to allow duplexes, triplexes and fourplexes in single-family zones. It calls for up to four total units, including ADUs, without splitting the lot, on parcels of at least 3,000 square feet. The draft ordinance text in the city's September 24, 2026 Phase 1 attachment turns that policy into rules a buyer can check:
- Zones covered: R-RR, R-VLR, R-RLD and R-RDIV.
- Lot size: a single lot of at least 3,000 square feet, with no subdivision.
- ADUs count: accessory dwelling units and junior ADUs count toward the four.
- Permitting: by right, with no conditional use permit, no Site Plan and Architectural Review, and no other discretionary review.
- Density cap: the zone's maximum density doesn't apply. The units don't have to be in separate buildings and may be sold as condominiums.
- Still applies: height, setback and lot coverage standards, plus the parking rules in Chapter 11.
- Excluded: designated landmark sites, properties inside a designated historic district, and sites under Chapter 16 hillside protection.
Waiving the density cap is a bigger change than it sounds. The adopted plan sets the low-density residential designation at 2.6 to 12 units per net acre. Four homes on a 3,000-square-foot lot works out to roughly 58 units per acre. One speaker at the October 13 hearing raised that figure and estimated that about 16,000 parcels could be affected, according to an unofficial voice-to-text transcript of the meeting. That parcel count was one person's estimate during public comment, not a city figure. The math on a minimum-size lot holds either way.
Why the zone and historic status matter more than the neighborhood name
Because of the exclusions, two houses on the same street, or a few blocks apart, can end up on opposite sides of this rule. A house on a designated landmark site, or one inside a designated historic district, can't use the four-unit path no matter how large its lot is. Neither can a lot under hillside protection. A plainer house in an R-RLD zone outside those districts can.
That interacts with how prices split across town. In BAREIS's September 2026 numbers, the 16 residential sales in Petaluma East averaged $794,563 and 34 days on market. The 20 sales in Petaluma West averaged $1,364,120 and 45 days. Those are averages across all residential property types, not single-family medians, so treat them as a rough picture. When a lot qualifies, the right to add units doesn't depend on what the existing house would sell for. On a lower-priced lot, that right makes up a bigger share of what you're paying for. So the same rule can affect the price math differently in different parts of Petaluma.
Countywide, the market gives buyers some room to look into these details before they commit. The California Association of Realtors' August 2026 report put Sonoma County's median single-family price at $790,000, down 5.1% from a year earlier. The same report showed 3.7 months of unsold inventory, unchanged from August 2025, and a median of 60 days on market, down from 67. With homes taking about two months to sell, you usually have time to check a parcel's zone before the offer deadline.
Parking decides how many units actually fit
Even with the density cap waived, a qualifying four-unit project still has to meet Chapter 11 parking. Phase 1 changes those numbers too. According to the October 8 staff memo, the current code requires a space for every bedroom, so a three-bedroom apartment needs three. The amendment switches to unit size: half a space for a studio, one for a one-bedroom, and one and a half for two bedrooms or more. It also drops the current rule that a project must provide at least 1.5 spaces per unit overall. That means a building of studios would go from 1.5 spaces per unit to 0.5.
On a 3,000-square-foot lot, that difference can decide what fits. Four two-bedroom units would still need six spaces. Four studios would need two. The General Plan floated going lower, to 0 or 0.5 spaces per unit across neighborhood infill. Phase 1 doesn't go that far. Reductions tied to nearby transit or amenities wait for Phase 2. The staff memo notes that state law already removes parking minimums within half a mile of a major transit stop.
Bigger buildings come later, and only in a few places
The plan's taller buildings are limited to specific spots. Its 15-minute activity centers are named locations.
- Town Centers, 3 to 6 stories: Marina, Lucky and Magnolia, the Downtown SMART Station, River Plaza Center, Washington Square Center and the North Petaluma SMART Station.
- Neighborhood Centers, 1 to 3 stories: Leghorn Marketplace, Casa Grande Center, Adobe Creek Center, Deer Creek Village, Western and Baker, the School District Office, the Bowling Alley and Veterans Center, River Park Center and Foundry Wharf.
- Activated Parks and Mini-Centers: Lucchesi Park, McNear Park, Caulfield and Crinella, City Hall, the Airport and Ray's.
Only one parcel can go to eight stories. It's the SMART-owned property directly next to the Downtown SMART station. The plan also names East Washington and Petaluma Boulevard North and South as key corridors for infill. Phase 1 does map new mixed-use zones onto corridor parcels. The detailed standards that shape what gets built there are scheduled for Phase 2, along with the transit-oriented overlays. The Petaluma North Station Specific Plan is on a separate track. Its schedule shows adoption and environmental review in Spring 2027.
If you're buying near Washington Square, Lucky and Magnolia or the North Petaluma station, the land-use map tells you what the city intends for those areas. The final height and design rules there won't be settled until at least mid-2027.
Quick answers
Can I build four units on a Petaluma lot today? The by-right four-unit path is in the Phase 1 draft. It becomes law only after the City Council adopts it, and its first reading is tentatively set for November 9, 2026.
Does every single-family lot qualify? No. The draft covers the R-RR, R-VLR, R-RLD and R-RDIV zones on lots of at least 3,000 square feet. It excludes designated landmark sites, designated historic districts and hillside-protection sites.
Will the downtown station area get taller buildings soon? The eight-story designation applies only to the SMART-owned parcel next to the Downtown station. The detailed transit-area rules are planned for Phase 2.
This post is general information about city rules, not legal, tax or financial advice. Before you rely on any of it for a purchase or a project, confirm your parcel's situation with the City of Petaluma's planning staff or the right professional.
When a house you're considering might qualify for more homes on the lot, its zone and historic status belong in the offer conversation alongside the inspection report. Summer Olson Stubblefield can help you pull those details for the addresses on your list before November 9 and keep you posted as the council vote lands. Let's talk about your next move.
