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Manufactured Homes/Mobile Homes

Manufactured Homes in Thurston County

manufactured home photoThurston County has requirements for manufactured homes to ensure that they are structurally sound and in good repair.

Permit Applications

A Manufactured Home Placement permit is required to place a new or used manufactured home on a piece of property in unincorporated Thurston County. If a new septic system is proposed, the septic application must be submitted before the Manufactured Home Placement permit application.

Please see our Manufactured Home Permit Applications page.


Once you obtain a Manufactured Home installation permit, installation must begin within 180 days and an inspection must be approved. If no inspection is approved the permit will expire. Once an inspection is approved the permit will be active for an additional 180 days.

  • Click here for an Inspection Guide for Manufactured Homes
  • Click here for a Landing Construction Drawing for Manufactured Homes (For a complete list of construction drawings, click here.)
  • Click here for an Anchor Certification Card

Alterations / Minor Permits

Any change to an original manufactured home requires an alteration permit from the Washington State Department of Labor & Industries. It is illegal to rent, lease or sell any manufactured home that has been altered without a alteration permit, a subsequent inspection, and an insignia of approval from the Department of Labor & Industries (RCW 43.22.360(1)). An L&I fact sheet is available by clicking here.

Some examples of alterations include:

  • Heat pump/air conditioning installations
  • Wood/pellet/gas stove or furnace installations
  • Changing from electric to gas appliances
  • Electrical or plumbing changes
  • Structural changes or additions (doesn't apply to recreational vehicles)

Before making any alterations, the person who will actually do the work needs to contact the nearest L&I field office Factory Assembled Structures section to obtain an alteration permit and find out more. In Washington, any contractor who performs alteration work must be registered with L&I. Click here to get an alteration permit or look up contractors, or call 360-902-5800.

Getting a Parcel Number

Homes new to Thurston County must apply for a tax parcel number from the Assessor's Office. Click here for the required data sheet.

If the Manufactured Home is For a Family Member and on Your Property ...

To place a family member unit on your property, you will need to submit a Family Member Unit Affidavit. By using this form, you state that a family member will be staying in the unit and that you will remove the unit if the family member moves -- in other words, that you won't rent out the unit to another person.

To Replace a Manufactured Home in a Mobile Home Park ...

To replace a manufactured home in a mobile home park, you will need to submit a detailed site plan showing where the manufactured home will be placed, the distance between neighboring manufactured homes, and locations of existing septic tanks and drainfields. Click here for a Replacement of Manufactured Homes in Mobile Home Parks guide.

Title Elimination Process

Owners of manufactured/mobile homes have an option in the titling process of their home. Owners may eliminate the separate title and opt to record their home with their land as real property. This process is usually done for financial reasons. A mortgage company may require it. Click here for the Title Elimination Form.

County Code Relating to Manufactured Homes

  • 14.44 - Building and Construction: Mobile  Homes
  • 20.31 - Zoning: Mobile Home Park Standards and Regulations
  • 21.63 - Lacey Urban Growth Area
  • 22.48 - Tumwater Urban Growth Area Zoning: Manufactured Homes
  • 23.05 - Olympia Urban Growth Area zoning: Villages and Centers

Contact Us

     Phone: (360) 786-5490. TTY/TDD call 711 or 1-800-833-6388.  E-mail: permit@co.thurston.wa.us.


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