Ventura County ADU Guide

Fillmore

ADUs are approved ministerially. The first approval is an ADU Administrative Clearance; construction plans and a building permit application follow.

Official source verified 2026-08-16Official jurisdiction resource ↗
01 / Plan path

Choose the right production starting point.

ADUs are approved ministerially. The first approval is an ADU Administrative Clearance; construction plans and a building permit application follow.

Express PlanStarting at $4,500

For a qualifying jurisdiction preapproved plan adapted into the property-specific architectural production set.

Custom PlanStarting at $6,500

For an original floor plan and architectural production set developed around the property and homeowner.

02 / Size + fee checkpoints

Size affects more than floor area.

ADUs and JADUs are allowed in all residential land use categories and on mixed-use and multifamily lots. A unit may be attached to, within, or detached from the primary dwelling, and architectural styling must match the primary residence.

Fees require confirmation with the Planning Department. The City publishes its ADU ordinance and application forms on its ADU page.
500 SFConfirm school-fee assessment rules750 SFState impact-fee protection checkpoint1,000 SFTwo-bedroom state minimum allowance1,200 SFCommon local upper-range checkpoint
03 / Site conditions

Property conditions can change the path.

  • Zoning and lot configuration
  • Architectural match to the primary residence
  • Fire access and water supply
  • Flood conditions along the Santa Clara River corridor
04 / Consultant screen

Likely disciplines to evaluate.

  • Structural engineering
  • Title 24 energy documentation
  • Survey where boundaries require it
  • Civil or geotechnical review when triggered

Consultants are retained only when required by the property, design, or reviewing agency. Their proposals and coordination are separate from the architectural production fee unless stated otherwise in the agreement.

05 / Property-specific next step

Turn the guide into a preliminary project report.

Enter the address to screen jurisdiction, mapped constraints, likely agencies, drawing requirements, consultants, and the preliminary fee path.

Check the property →Email Bennett Design Studio →
Important: This guide is general planning information, not a zoning determination, permit approval, fee quote, or guarantee of feasibility. Current parcel records, adopted codes, agency interpretations, utility requirements, site investigation, and written agency confirmation control.