ADU Builder Service Areas Around Westlake Village

One Westlake Community, Three ADU Permitting Agencies

The Westlake master plan was laid across the Los Angeles and Ventura county line. Only the Los Angeles County third became the City of Westlake Village, incorporated in 1981. The Ventura County portion was annexed into Thousand Oaks in 1968 and 1972. Surrounding communities such as Lake Sherwood and Hidden Valley remain unincorporated Ventura County land.

For an ADU, that history decides nearly everything procedural: which ordinance sets size and height, who checks the plans, which fees apply and whether Los Angeles County's pre-approved conversion plans can be used. Before we start any design, we confirm the governing agency for the specific parcel.

ADUs Inside the City of Westlake Village

First Neighborhood, Three Springs and Lakeshore are within the City of Westlake Village. Here, City planning staff approve ADUs through an administrative Zoning Clearance, and Los Angeles County Building and Safety, under contract with the City, handles plan check through EPIC-LA and inspections. Water comes from the Las Virgenes Municipal Water District, and sewer laterals are the owner's responsibility up to the City main.

These neighborhoods tend to have single-family homes on established tract lots, with garage conversions and junior ADUs often the most direct options. Part of Westlake Island also falls inside the City.

Thousand Oaks and Ventura County ADU Service Areas

Southshore Hills and North Ranch carry Westlake Village mailing addresses but are in the City of Thousand Oaks, which handles both planning and building review. Hillsides and protected oaks shape ADUs in both neighborhoods, and HOAs are common. Some Westlake Island parcels and some homes marketed as Three Springs fall on this side of the line too.

Lake Sherwood and Hidden Valley are unincorporated, so ADUs there go through the County of Ventura. Lake Sherwood brings gated communities and club rules. Hidden Valley brings ranch-sized parcels, private wells and septic systems.

How to Find the Right ADU Area Page

Each area page below covers the permitting agency, the lot and housing patterns that matter for an ADU, the unit types that usually fit, and the questions owners there ask most. If your neighborhood is not listed but has a Westlake Village address, send us the address anyway. We will tell you which agency governs it and whether we can help.