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.

Please note: as of June 30th, 2022, the City suspended its ADU water allocation program to be certain that water is available for ADU projects currently under review. New applicants residing in the Monterey Peninsula Water Management District area without an allocation are instructed to calculate their project’s water needs using the Residential Water Release Form and Water Permit ApplicationIf applicants can retrofit existing fixtures and proceed with their ADU project without needing to purchase ADU water, they are welcome to submit their building permit and water permit application. 

Please contact planning staff with any questions about water or about completing the water form.


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: Apply in person or through our portal to submit the Residential Building Permit Application to the City’s Building Department. Submit your MPWMD Water Release Form and Water Permit Application with your plans. After you submit your application, staff will contact you to guide you through the process.
Note about Fees: 
  • For clarity calculating fees, contact Building Department staff for assistance: (831) 899-6825,
  • Fees Based on Fire Rating Type IIB, IIB, IV, VB
  • Plan Check fees are waived for City of Seaside Pre-approved ADU plans.

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. 

Note about Fees: 
  • Please contact MPWMD staff for assistance calculating water permit fees: (831) 658-5601,

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 Sample

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

Plan check fees will be waived for property owners who use the Pre-Approved ADU plans.

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