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If you add an ADU to your home, you can rent one or both of the units. If your home was built before 1979, one or both of the units may become subject to the City’s Rent Stabilization Ordinance (RSO). To determine if an ADU triggers the RSO on your property, call (866) 557-7368. For more information about the RSO, visit homeforrenters.org.

Almost every lot in LA is unique, so this guidebook addresses the most common conditions. There are various types of ADUs that work on different lots. For example, if a detached ADU will not fit in your backyard, you might attach a new unit to your current house. If the garage behind your house is inconveniently located, you could demolish and rebuild it with an ADU above. Sketch your ideas as suggested in the guidebook, and talk them over with the Dept. of Building and Safety.

There are some limits on the size of an ADU, based on the size of your lot and existing house. First, an attached ADU cannot be bigger than 50% of the existing house. For example, if your existing house in 2,000 sq. ft., the attached ADU cannot exceed 1,000 sq. ft. in size. Second, there is a “baseline mansionization ordinance” that usually restricts the total square footage of all structures on a lot to 45% of the total lot size. For example, if your lot is 10,000 sq. ft., the total built area (existing house, ADU, garage, etc.) cannot exceed 4,500 sq. ft. In addition, most ADUs cannot exceed 1200 sq. ft. The Dept. of City Planning will need to verify the specifics related to your project.

Although this guidebook focuses on new construction, you may be able to get permits that will legalize an existing rental unit on your property. You can contact the Dept. of Building and Safety for more information.

If your existing garage is at the front of your house, in most cases you cannot convert it into an ADU. You may be able to build an ADU elsewhere on your property. You should check with the Dept. of City Planning.

No, both the existing house and the ADU can be rental units.

No, you can only sell your house and ADU together. ADUs can be rental units or occupied by the homeowner or family members.

Many lots in LA are within a half-mile of transit, so that ADU parking will not be required. The City publishes a transit map you can download here. First, see if your lot appears to be within a half-mile radius of a bus stop, rail station, or a dedicated space where a shared-vehicle is parked. Second, call the Dept. of Building and Safety to give your property address. They can confirm whether you need to provide parking for your ADU.

There are a number of ways to pay for the construction of an ADU. A common way is to borrow from a home equity line of credit if you have equity in your existing house. Other ways can be more complicated: 1. You could refinance your existing mortgage to take out a larger loan to provide cash for ADU construction (this will require equity in the home); 2. You may be able to obtain a private construction loan to build the ADU and refinance the loan with a new mortgage when construction is complete. You should start by talking to the bank that holds your current mortgage.

Since the size and construction of each ADU will differ, it is impossible to estimate the cost of your ADU. The cost per-square-foot of an ADU is likely to be the same as any other new residential construction; builders and architects can give you rough estimates.