How the Does It Split? property checker works

What happens when you type an address

We find your parcel on the county map, pull its lot lines, zoning and the buildings already on it, and check it against state SB 9 rules and the city's own standards. Then we look for the best place to draw a split line: a straight line at least 4 ft past the house that leaves a new lot of at least 1,200 sq ft and at least 40% of the original, with a way to reach the street. If a straight line doesn't work, we try an L-shaped one.

Where SB 9 applies. SB 9 covers single-family lots in cities that include an urbanized area, and in urbanized parts of unincorporated counties. All seven cities the checker covers (Encinitas, Carlsbad, Poway, San Marcos, Vista, Escondido and Solana Beach) qualify. Lots in unincorporated San Diego County, or in cities whose rules we haven't loaded, go to a hand check instead of getting an automatic answer.

You get one of four answers: looks like it splits, needs a closer look, probably not, or we'll check by hand (for areas where we haven't loaded the city's rules). We never say a flat yes, because some things only a person can confirm.

What the screening result means

• Looks like it splits: the maps show a split line that clears the size tests and a way to reach the street. A survey and city review still decide it.
• Needs a closer look: no clean line showed up on the maps, but a look by hand often finds one.
• Probably not: a mapped constraint, like zoning or a floodway, rules the lot out on public data. An automated negative isn't proof the lot is legally ineligible; the data can be wrong or out of date.
• We'll check by hand: the lot is outside the cities whose rules we've loaded, so a person reviews it.

What the checker can and cannot confirm

Our free checker is a preliminary screening tool. It uses publicly available parcel, zoning, building and hazard data to identify possible SB 9 lot split configurations. It does not independently verify title, deed restrictions, easements, ownership history, tenant occupancy, lender consent, utility capacity, surveyed boundaries or final agency approval. A licensed surveyor, relevant city staff and other qualified professionals may be needed before relying on a proposed split.

In particular, it can't know:

• Whether a home that would be torn down or altered was rented in the last three years, whether the lot sits in a historic district, or whether it came from an earlier SB 9 split.
• Easements, CC&Rs and anything else on title.
• Where the driveway, patio and smaller sheds are. Map outlines miss some of them.
• Slopes and floodplain that some cities subtract from lot area.
• Exact lot lines. County lot lines aren't a survey and can be off by a few feet.

That's why every lot gets a look by hand before any offer, and why the checker's answer is a starting point.

About the operator

Does It Split? is operated by Grant Thiem, a California licensed real estate broker (DRE #01984787), through On Point Real Estate (OPRE, Inc., DRE #02112470). The service helps homeowners understand whether a potential SB 9 lot split deserves further review using public mapping information and property-specific follow-up. Grant is not a surveyor, engineer, attorney or tax advisor. Questions: 858.227.4707 or grant@opreinc.com.

Where the rules come from

State law: California Government Code §§65852.21 and 66411.7. City rules: each city's published SB 9 ordinance, bulletin or handout, zoning code and fee schedule, linked from its city page. Rules last reviewed October 2026.