What is a “Two-unit Development” versus an “Urban Lot Split”?

SB 9 FAQ 2


The diagram on the left depicts a traditional rectangular shaped single-family parcel with what is known under SB 9 as a “Two-unit Development”.   In this scenario, a property owner with a single-family home may construct a second home on the property and may also build an Accessory Dwelling Unit and Junior Accessory dwelling unit resulting in the development of a total of four dwelling units on a single-family parcel.


The two diagrams on right depict scenarios that are under the “Urban Lot Split” category.  In these two Urban Lot Split Scenarios, the property owner may subdivide a single-family parcel into two lots and in these scenarios ADUS or JADUS are not allowed in conjunction with Urban Lot Splits.

The middle diagram shows a traditional rectangular lot split down the middle, resulting in two lots.  Each of these lots, can then be combined with the Two-unit Development concept, which may result in each lot having a total of two units.  

The diagram on the far right, depicts a “flag style” urban lot split, where access to the new lot at the rear has access to the street and/or public right of way from a narrow strip of land, resulting in the rear lot resembling the shape of a flag. In the Urban Lot Split scenarios, each lot may accommodate up to two units.

Show All Answers

1. What is SB 9?
2. How do I know if I can develop my property under SB 9?
3. Is there a map where I can check if my property can be affected by SB 9?
4. How many units can I build?
5. What is a “Two-unit Development” versus an “Urban Lot Split”?
6. What are the requirements for development under Tustin’s SB 9 Ordinance?
7. What kind of approval do I need to build using SB 9?
8. My property is in the City’s Cultural Historic District, can I build on my property using SB9?
9. Can my HOA prohibit me from building on my property using SB9?
10. Will I be notified if one of my neighbors decides to build on their property using SB9?