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Thousand Oaks, Ventura County
ADUs & home additions in Thousand Oaks, CA.
Garage conversions, backyard ADUs and room additions in Thousand Oaks, Newbury Park and the wider Conejo Valley.
Building in Thousand Oaks
Adding space in the Conejo Valley.
Thousand Oaks homes tend to sit on larger lots with established landscaping, slopes and HOA design standards, all of which shape where an ADU or addition can go.
Grading, drainage, access for equipment and how the new structure will relate to neighbors should all be looked at before design. On sloped lots, the foundation design and the route to the sewer usually drive cost more than the square footage does.
The city adopted a new ADU ordinance in March 2026, and HCD has already identified issues with parts of it. That is not unusual; ADU rules across California are in flux. What matters for you is knowing which standards actually apply to your lot before you spend money on plans. Homeowners' associations also cannot block a qualifying ADU permit under state law, though HOA design guidelines may still affect finishes.
What to know in Thousand Oaks
- Thousand Oaks adopted ADU Ordinance No. 1747-NS on March 10, 2026. It allows ADUs on single-family lots in the R-A, R-E, R-O, R-1, RPD and HPD zones and on multifamily lots in the R-2, R-3, RPD and MU zones.
- HCD's June 2026 review found five issues with the new ordinance, including its ban on exterior stairs. Where local rules conflict with state law, state law controls.
- HCD had also found the city's 2025 ordinance out of compliance, including a 16-foot cap on detached ADU height that did not account for state allowances near transit.
Project types in Thousand Oaks
ADUs and additions in Thousand Oaks.
ADUs
Accessory dwelling units of every type, from feasibility and permits through final inspection.
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Garage-to-ADU Conversions
Reuse an existing garage for the fastest, most economical path to a complete ADU.
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Detached ADUs
Freestanding backyard homes with full foundations, framing, utilities and finishes.
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Attached ADUs
Units that share a wall with the main house, including attached-garage conversions.
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Junior ADUs (JADUs)
Up to 500 square feet created within your existing home, with an efficiency kitchen.
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Home Additions
Room additions, kitchen expansions and roof decks built to blend with your home.
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Second-Story Additions
Build up instead of out, with structural evaluation, engineering and framing done right.
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Primary Suite Additions
Master bedroom and bathroom additions with closets, showers and soaking tubs.
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Thousand Oaks ADU & addition questions
What ADU rules apply in Thousand Oaks in 2026?
The city adopted Ordinance No. 1747-NS in March 2026. HCD reviewed it in June 2026 and identified five issues, so some provisions may change. The contractor confirms current requirements for your lot during feasibility.
Can my HOA stop me from building an ADU?
State law does not allow an HOA to prohibit or unreasonably restrict a qualifying ADU, though reasonable design guidelines may still apply.
Do you serve Newbury Park?
Yes. Newbury Park is part of the City of Thousand Oaks, and we serve the whole Conejo Valley, including Westlake Village and Agoura Hills.
Nearby areas
Also serving areas near Thousand Oaks.
Free consultation
Planning an ADU or addition in Thousand Oaks?
Share a few details about your property and the space you want to add. We will pass your request to a licensed local general contractor who specializes in ADUs and additions, and they will follow up directly.
- Free consultation and site visit
- A realistic budget conversation before you pay for plans
- A licensed general contractor from permit to final