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SB 9 lot split example: turning a backyard into a parcel

One lot, split on paper.

Here's how the numbers work on a typical North County lot. This is an illustration, not a real parcel map or an approved split: every city measures lot area and access a little differently, and the real lines come from a survey.

The lot

A 10,000 sq ft lot, 80 by 125 ft

The house sits toward the street with an unused backyard behind it. The goal: a new lot in back, a lot with the house in front, and a way for the back lot to reach the street.

Original lot	80 × 125 ft = 10,000 sq ft
Rear lot, main area	80 × 52.5 ft = 4,200 sq ft
Access strip (part of the rear lot in this example)	20 × 72.5 ft = 1,450 sq ft
Rear lot, gross area with the strip	5,650 sq ft (56.5%)
Front lot with the house	60 × 72.5 ft = 4,350 sq ft (43.5%)

Illustrative parcel layout: not a recorded map, survey, permit or guarantee of SB 9 approval. Gross area and the area a city counts for eligibility can differ. Building footprints, fire access, frontage and utilities still need review.

The tests

Does it pass?

Each lot at least 1,200 sq ft. On paper, yes: the front lot is 4,350 sq ft and the rear lot 5,650 sq ft gross.
The smaller lot at least 40% of the original. 40% of 10,000 is 4,000. The front lot is the smaller one at 4,350 (43.5%). If a city leaves the strip out of the rear lot's counted area, the rear lot counts as 4,200 (42%), still above 4,000. So this layout clears the size tests either way, which is why the example was drawn this way; it still needs a survey and city review.
A way to the street. The 20 ft strip runs down the side of the house. Fire code usually wants a 16 ft driveway in it, and a turnaround if the drive runs more than 150 ft.
The existing house. SB 9 doesn't require a setback for a structure that's already there, so the house can stay as is. New homes get 4 ft side and rear setbacks.

The fine print

Where it changes city by city

Owned strip or easement. Some cities let the strip be an easement over the front lot; others want it owned as part of the rear lot. Vista and Carlsbad want it owned; Encinitas allows either.
Does the strip count toward lot area? Some cities leave it out. That's why this example keeps the rear lot above 40% without it.
Slopes and easements. Some cities subtract steep slopes, road easements or floodplain from lot area.
What fits on the new lot. The rear lot's building area depends on the city's front setback, height, lot coverage and fire access rules.

Questions

Quick answers

What is an example of an SB 9 lot split?

A 10,000 sq ft lot, 80 by 125 ft, split into a 4,200 sq ft rear lot and a front lot with the house, connected to the street by a 20 ft access strip. Each lot clears 1,200 sq ft and 40% of the original.

Can the access strip be an easement?

In some cities. Encinitas allows an owned strip or a recorded easement; Vista and Carlsbad want the strip owned as part of the lot.

Does my house need setbacks from the new line?

SB 9 doesn't require a setback for an existing structure. New homes get 4 ft side and rear setbacks.

Is this example a real parcel?

No. It's an illustration. Real lines come from a survey and the city's review.

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More guides

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By city

Encinitas Carlsbad Poway San Marcos Vista Escondido Solana Beach Sell part of your backyard Mortgage guide Costs SB 9 vs. ADU How the checker works

General information, not legal, tax or financial advice. State law: Cal. Gov. Code §§65852.21, 66411.7. Last reviewed October 2026.