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    • Home
    • ADU Types
      • Attached ADU
      • Detached ADU
      • Garage Conversion ADU
      • Internal ADU + JADU
    • Service Areas
      • Aptos
      • Capitola
      • Felton
      • Los Gatos
      • Santa Clara
      • Santa Cruz
      • San Jose
      • Sunnyvale
      • Mountain View
      • Scotts Valley
      • Santa Clara County
    • About OCA
      • Contact Us
      • Your Local Owner
      • Our Project Gallery
      • OCA ADU Blog
      • Contractor Services
      • Home Remodeling
      • Metal Gates and Fences
    • ADU Cost Estimations
    • County Guidelines
  • Home
  • ADU Types
    • Attached ADU
    • Detached ADU
    • Garage Conversion ADU
    • Internal ADU + JADU
  • Service Areas
    • Aptos
    • Capitola
    • Felton
    • Los Gatos
    • Santa Clara
    • Santa Cruz
    • San Jose
    • Sunnyvale
    • Mountain View
    • Scotts Valley
    • Santa Clara County
  • About OCA
    • Contact Us
    • Your Local Owner
    • Our Project Gallery
    • OCA ADU Blog
    • Contractor Services
    • Home Remodeling
    • Metal Gates and Fences
  • ADU Cost Estimations
  • County Guidelines
Cost Estimation for ADU Projects

How much will my ADU cost?

The cost to build an ADU in Santa Cruz can vary significantly. Typically, a garage conversion of a relatively new garage is the least expensive option, while a custom stand-alone ADU or an ADU built on top of a garage tends to be more costly. Below is a breakdown of some basic costs. 

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OCA Builders CSLB #1047731

A Breakdown of ADU Costs

Soft Costs:

 

  • Planning and Building Department Fees: $10,000-20,000, depending on the size of the ADU and whether it is a conversion or a new construction.
  • Water, Sewer, and Fire Sprinkler Connections: $10,000-20,000, contingent on whether the existing services can be shared or if new services need to be tapped at the street. If you're in the Soquel Creek Water District, expect an additional $20,000-30,000 for a new water meter.
  • PG&E Electric Hookup/Panel Upgrade: $5,000-8,000, depending on whether you have a 200 amp panel at the main house, if a new service is required, and the distance the gas line needs to run from the shared meter (or opt for all-electric and add solar!).
  • Architectural Plans and Engineering: $15,000-35,000 for architectural plans, structural engineering, Title 24 energy modeling, and possibly a soils report. Garage conversions may require less in terms of engineering and soils reports, whereas stand-alone ADUs require more extensive structural engineering and may need a soils report.

Building Costs

 

  • Garage Conversions: $150,000-300,000, depending on the condition and size of the existing garage, proximity to utilities, and the extent of necessary upgrades.
  • Stand-Alone or Attached ADUs: $300,000-700,000, depending on size, site, accessibility, finishes, and building department requirements. Smaller ADUs typically cost around $650-700 per square foot, while larger ADUs over 800 square feet may see reduced costs due to economies of scale, especially with simpler designs and finishes.

 Note on Cost: ADUs generally have a higher cost per square foot compared to larger homes due to their smaller size and the inclusion of the most expensive rooms: the kitchen and bathroom. For those on a tight budget, a garage conversion is often the most affordable way to build an ADU and can offer the best return on investment when used as a rental. For new stand-alone ADUs, costs can be minimized with simple designs and affordable yet durable finishes. During the planning process, we can provide advice on how to keep costs down while maintaining high quality. 

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How Long Will It Take to Design, Permit, and Build?

At OCA Builders, your premier Santa Cruz ADU builder, we are committed to guiding you through the entire ADU construction process, ensuring a smooth and efficient journey from concept to completion. 

Typically takes about 4-6 months, depending on the complexity of the project. 


Usually requires another 3-5 months. 


Generally takes 6-7 months for garage conversions, 7-8 months for smaller stand-alone ADUs, and around a year for large ADUs. The timeline may vary depending on the project's complexity and the season (e.g., rainy weather can cause delays). 


See our project gallerySanta Cruz County Information

Pre-Designed ADU Plans Approved by Santa Cruz County

425 square foot studio or optional 1-bedroom and 1-bathroom with 76 square foot front porch. 


  • Choose between classic bungalow, coastal Mediterranean, and sleek modern. 
  • Permit fees: approximately $5,000* 

637 square foot 1-bedroom and 1-bathroom with 85 square foot front porch. 


  • Choose between classic bungalow, coastal Mediterranean, and sleek modern. 
  • Permit fees: approximately $6,000* 

998 square foot 2-bedroom and 1-bathroom with 62 square foot front porch. 


  • Choose between classic bungalow, coastal Mediterranean, and sleek modern. 
  • Permit fees: approximately $20,000* + Impact Fees** 

 * School District and Fire Department Review Fees will be due separately. These vary depending on which school district or fire agency serves your parcel. Fees are paid directly to those agencies prior to permit issuance.
** Impact Fees (e.g., Parks, Child Care) only apply to the 998 square foot design and do vary.

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OCA Builders: ADU Construction

331 Soquel Avenue, Santa Cruz, California 95062, United States

(831) 425-9183

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OCA BUILDERS: ADU CONSTRUCTION

331 Soquel Avenue

SANTA CRUZ, CA 95062

(831) 425-9183

INFO@OCABUILDS.COM

OCA Builders CSLB #1047731

Copyright ©2025 OCA Builders | All Rights Reserved

  • Home
  • Attached ADU
  • Detached ADU
  • Garage Conversion ADU
  • Internal ADU + JADU
  • Aptos
  • Capitola
  • Felton
  • Los Gatos
  • Santa Clara
  • Santa Cruz
  • San Jose
  • Sunnyvale
  • Mountain View
  • Scotts Valley
  • Santa Clara County
  • Contact Us
  • Your Local Owner
  • Our Project Gallery
  • Contractor Services
  • Home Remodeling
  • Metal Gates and Fences
  • ADU Cost Estimations
  • County Guidelines

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