Accessory Dwelling Unit (ADU)

Introduction

Accessory Dwelling Units (ADUs) offer homeowners a flexible way to add infill housing while staying within the density already allowed on their property. Humboldt County’s ADU ordinance implements recent changes to California law (Gov. Code §§ 65852.2–.22) and the California Building Standards Code (Title 24). These rules provide clear, ministerial standards so that at least one ADU—or a Junior ADU (JADU)—can be created or converted on any lot that permits single-family or multifamily residential use, including tiny houses and manufactured homes that meet applicable safety standards.

Minimum Documents for Permit Submittal

The following documents are required for all permit applications for a new ADU. If you are unsure what these documents are or how to get them see our Construction Documents page. It will describe what the document is, why it is required, and how you can get it.

Forms

Design Documents

  • Site Plan
  • Construction Plans
  • Energy Calculations

NOTICE: Other documents will likely be required depending on where and how complex of a structure you are building. For example, if your energy calculations specify a minimum photovoltaic (PV) size you will be required to submit PV plans. See the Construction Documents page to see if other documents may be required for your permit submittal.

Quick Steps to Permit Issuance

Follow the below steps to start a permit application for a new ADU.

  1. Register for an Accela account (see our Accela Support Resources).
  2. Upload your required documents (see our Accela Support Resources and Step 3 on First Time Applying for Building Permit).
  3. Move through step 4 Preliminary Site Inspection and step 5 Plan Check described on First Time Applying for a Building Permit webpage.
  4. Once the permit is issued use the Inspections page to schedule inspections and change your issued permit if necessary.