What Is An ADU?

​​​​​​​According to the Los Angeles County Department of Regional Planning, “An ADU is a dwelling unit with a full kitchen and bathroom, which is an accessory use to a primary or main single-family residence. The ADU can be used as a rental, but cannot be sold separately from the primary or main single-family residence. The existing residence must be a legally established structure.”

​​​​​​​ADUs can provide an easy source of rental income for homeowners and low-cost housing for renters. They also add manageable density to single-family areas where new apartment complexes would be difficult to construct. – Curbed

Citywide, there are an estimated 50,000 secondary units on residential lots, from mother-in-law cottages to converted garages. But many of them lack permits, and many more potential ADUs have never come to fruition because of issues like the cost to build extra parking that outdated city codes required.

A series of state laws enacted in January 2017 lifted many of those barriers. As a result, about 2,000 permits were requested in L.A. last year, a 658 percent increase from the average between 2012 and 2016, according to city data. With half a million single-family lots citywide, the mayor’s office once argued there’s room for an even greater increase, which is where city hall’s Innovation Team comes in. “If we permit them, families build them,” says its director, Amanda Daflos. – Los Angeles Magazine

Am I Allowed Build An ADU On My Property? What Are The Rules And Requirements?

In general, an ADU is permitted with a Site Plan Review if:

• The property is zoned R-1, R-2, R-3, R-4, R-A, A-1 and A-2, or another zone where a single family residence (SFR) is allowed by right with a plot plan (ministerial review).
• Only one legal SFR exists on the property or is proposed to be built concurrently with the ADU.
• You propose to convert an existing guest house, mobile home, or caretaker’s residence to an ADU.

An ADU is not permitted if the property:

• Is not zoned to allow a SFR by-right
• The ADU is intended for sale separate from the primary SFR.
• Contains other habitable structures beyond the primary single-family residence, except a pool house accessory to an existing swimming pool.

For more details, see this document specific to Los Angeles County.
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​​​​​​​​​​​​​​How Much Does It Cost?

Based on our team’s conversations with some local architects, it seems that the cheapest someone could build an ADU for would depend on if it was from the ground up or from an existing structure. It would also several other factors (i.e. where is the sewer line, power, gas line, parking etc.) If it was as simple as converting an existing 2 car garage and all the utilities were close you’re talking maybe $125k-$175k for a very basic, simple unit.