ADU Guide

4899 Sea Crest Ct. Seaside, CA
Seaside Gateway Sign_Side_blur edited

Accessory Dwelling Units (ADUs), also called “in-law units,” “granny units”  and more are housing units that can be attached to the main house or detached accessory structures. California state law has evolved to recognize ADUs as an innovative option in addressing California’s housing shortage.

 There are many benefits of adding ADUs to your property, including:

  • Creating more affordable housing in our Seaside community
  • Providing housing for relatives or friends
  • Allowing seniors to age-in-place
  • Increasing your property’s value
  • Providing extra income as a rental unit

The City of Seaside is committed to making it easier to add an ADU to your single-family or multi-family property.


Follow these steps to apply for your ADU building and water permits: 

  1. Design: Decide if you’ll convert an existing space in the main house, an accessory structure or build a new addition or detached ADU. Draw your plans; work with an architect, or use the City’s Pre-Approved ADU plans.
  2. Calculate your water needs: Work with your architect, designer or MPWMD to complete MPWMD’s  Water Release Form and Water Permit Application. This will help you determine what retrofits are needed for your existing home and estimate any water allocation still needed from the City.
  3. Plan Check: Email your application for a building permit with the City’s Building Department. Submit your MPWMD Water Release Form and Water Permit Application with your plans. Staff will contact you to guide you through the process.
ADU plan check fees box

1Attached Fee Schedule will give you a sense of the fees. See highlighted sections. 

2Plan Check fees waived for City of Seaside Pre-approved ADU plans.

3Inspection Fees are waived for all ADUs


  • For clarity calculating fees, call the Building Department or Planning staff for assistance.
  • Fees Based on Fire Rating Type IIB, IIB, IV, VB

4. Request City ADU Water Allocation : If additional water is needed, you may submit the City’s ADU Water Allocation Application to request an ADU Water Allocation. The cost is $2,500 per (1) fixture unit ( or .01 Acre Feet) up to a maximum water allocation of 6.8 fixture units  ( or .068 Acre Feet) per ADU. See attached ADU Water Allocation Policy. Please include your MPWMD Water Permit Application and a PDF copy of the existing and proposed floor plans showing all water fixtures and appliances. Submit all documents to the City’s Housing Program Manager. The City’s Water Allocation Committee will review your application to issue a Water Allocation approval.

5. Submit Water Permit Application: Review MPWMD's water permit process guidelines.  Electronically submit one set of the approved building plans, your City Water Allocation Approval form (if applicable) and your Water Permit Application to the MPWMD. The water permit process takes approximately one week to prepare documents for notarized signature and recording. A Water Permit is issued after the documents record, payment is received, and the Water Permit is signed. 

MPWMD Fees box for web

6. Get your Building Permit and Start Building: Return your plans, your Water Permit and your City Water Allocation Approval (if applicable) to the Building Department to receive your building permit. Upon completion of construction, MPWMD and the City will complete final inspections and issue a Certificate of Completion.

Congratulations! You have yourself an ADU!

Pre-Approved ADU Plans

Pre-Approved ADU Plans 1st page image
To streamline the permitting process, the City of Seaside has made available free of charge ADU plans that have been reviewed and stamped approved by Seaside’s Chief Building Official.

Above is a sample of the plans including the cover page, floor plans and elevations (8 of 24 pages).
Any user of the Pre-Approved ADU Plans is required to sign a Liability Waiver. Please email the signed Liability Waiver
to the Housing Program Manager to request the full plan set or call 831-899-6772.

Permit Fees Waived
Permit inspection and plan check fees will be waived for property owners who use the Pre-Approved ADU plans, an estimated savings of $2,525.

Follow the steps at the left to apply for a building permit using the Pre-Approved ADU plans. 

Specific Site Plan Required
Please prepare a site plan to submit with the Pre-Approved ADU plans. The site plan will include the location of your existing structure(s), property lines, and the proposed location of the new ADU in relation to existing structure(s). Site Plan must include measurements from the proposed ADU to other structures and the property lines.

You may hand draw or use a PDF or image editor to place shapes on this blank Site Plan sheet to represent existing and proposed structures.

Site Plan Blank

Blank Site Plan_Pre-Approved ADU Plans