--- title: "ADU Construction Cost in Thousand Oaks (2026)" description: "ADU construction in Thousand Oaks, CA: $335–$560 per sq ft in 2026. A mid-size job runs $101k–$202k. Free bids from vetted builders." url: https://keystoneconnect.us/cities/thousand-oaks/adu updated: 2026-10-27 --- Thousand Oaks, CA · Conejo Valley & East County # ADU construction prices in Thousand Oaks, CA: 2026 ranges An ADU construction in Thousand Oaks costs $335–$560 per sq ft, with a typical mid-size ADU running $101k–$202k. Small projects start around **$67k**; large or high-end work can reach **$504k** or more. As of 2026, costs in Thousand Oaks run about 12% above the LA County baseline due to HOA standards, hillside lots, and wildfire-zone rules. Updated October 2026 Get matchedCost by size Cost per sq ft $335–$560 per sq ft ## ADU Construction Cost by Size in Thousand Oaks Totals adjusted for the Thousand Oaks market (1.12× LA County baseline). Ranges include labor, materials, permits, and contractor overhead. ADU Construction cost by size in Thousand Oaks, CA | Size | Type | Range | Low | High | | --- | --- | --- | --- | --- | | Small | JADU / studio | 150–400 sq ft | $67k | $146k | | Medium | 1-bed garage conversion | 400–600 sq ft | $101k | $202k | | Large | Detached 2-bed | 800–1,200 sq ft | $280k | $504k | ## What Affects ADU Construction Cost in Thousand Oaks? - ADU type (JADU vs attached vs detached). - Site prep and grading. - Utility connections. - CA Title 24 energy compliance. - City ADU permit timeline. - Thousand Oaks market premium: local pricing reflects HOA standards, hillside lots, and wildfire-zone rules, which shifts totals about 12% above the LA County baseline. ## Get exact ADU construction bids in Thousand Oaks Two or three licensed builders who work in Thousand Oaks, pricing the same scope. Tell us about your project[or call (818) 482-8365](tel:+18184828365) ## ADU Construction Sub-Type Comparisons ### Garage Conversion ADU vs Detached ADU Garage conversions reuse the existing slab and shell at $90k–$180k; a detached new-build ADU runs $250k–$450k but unlocks larger floor plans and higher rent. ### Junior ADU (JADU) vs Attached ADU A JADU (≤500 sq ft, within the home) runs $60k–$130k and shares utilities; an attached ADU is a true second unit at $150k–$350k with its own entrance and meter. ## How to Get the Best Price on a ADU Construction in Thousand Oaks 1. Get line-itemized bids from two or three builders on the same scope; Thousand Oaks ADU construction pricing commonly varies 10–25% between contractors. 2. Lock major materials and finishes before signing; mid-project change orders are the #1 cost driver on ADU construction jobs. 3. Bid in shoulder seasons (Jan–Mar or Sep–Oct) when Thousand Oaks contractor schedules are open and rush premiums disappear. 4. Verify CSLB license, insurance, and bond before paying any deposit. California caps deposits at $1,000 or 10% of contract, whichever is less. ## What is an ADU construction? An accessory dwelling unit (ADU) is a second, self-contained home on a single-family lot, with its own kitchen, bathroom and entrance. It can be detached, attached to the main house, a converted garage, or a junior ADU of up to 500 sq ft inside the existing home. ## How to get an accurate price 1. 1.Write down the scope: size, any layout changes, the finish level, and who supplies fixtures and materials. 2. 2.Get bids from two or three licensed builders who work in Thousand Oaks, all pricing that same ADU construction scope. 3. 3.Line the bids up item by item. Check allowances, permits, exclusions, and whether overhead and profit are shown. 4. 4.Before any deposit, check each builder's CSLB license and insurance. As of 2026, California caps a home improvement down payment at $1,000 or 10% of the contract, whichever is less, according to the Contractors State License Board. Already have a bid? [Grade it in two minutes](https://keystoneconnect.us/grade-my-bid) or read [how to compare quotes](https://keystoneconnect.us/pillars/how-to-read-compare-contractor-quotes). ## Questions about ADU Construction in Thousand Oaks ### How much does an ADU construction cost in Thousand Oaks, CA? + An ADU construction in Thousand Oaks costs $67k–$504k, with a typical mid-size ADU running $101k–$202k. Per-unit pricing falls in the $335–$560 per sq ft range. ### Do I need a permit for an ADU construction in Thousand Oaks? + Yes for most scopes — the city building department requires permits any time you move plumbing, gas, electrical, or alter structure. Like-for-like cosmetic refreshes generally don't. ### How long does an ADU construction take in Thousand Oaks? + Plan for 4–14 weeks of construction in Thousand Oaks depending on size and complexity, plus 2–8 weeks for design, permits, and material lead times. ## Official sources - [Look up a contractor's license on the CSLB website](https://www.cslb.ca.gov/OnlineServices/CheckLicenseII/CheckLicense.aspx) - [California home improvement contract requirements (Business and Professions Code §7159)](https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=BPC§ionNum=7159) Need more answers? Visit our [contractor FAQ hub](https://keystoneconnect.us/faq). ## Get Matched with Licensed Thousand Oaks Contractors Tell us about your ADU construction and we'll line up two or three licensed builders who work in the area. Ventura County overview [See ADU Construction costs across all Ventura County cities →](https://keystoneconnect.us/cost/ventura-county/adu) Before you sign a bid [See a real ADU construction bid torn down line by line →](https://keystoneconnect.us/estimate-teardowns/adu) ## Related Thousand Oaks Projects [All projects← Back to Thousand Oaks](https://keystoneconnect.us/cities/thousand-oaks)[Thousand OaksKitchen Remodel Cost →](https://keystoneconnect.us/cities/thousand-oaks/kitchen-remodel)[Thousand OaksBathroom Remodel Cost →](https://keystoneconnect.us/cities/thousand-oaks/bathroom-remodel)[Thousand OaksRoom Addition Cost →](https://keystoneconnect.us/cities/thousand-oaks/room-addition) ## ADU Construction in Nearby Cities [Camarillo, CAADU Construction Cost in Camarillo →](https://keystoneconnect.us/cities/camarillo/adu)[Ventura, CAADU Construction Cost in Ventura →](https://keystoneconnect.us/cities/ventura/adu)[Simi Valley, CAADU Construction Cost in Simi Valley →](https://keystoneconnect.us/cities/simi-valley/adu)