M/M Home Installation Requirements

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Find a certified mobile/ manufactured home installer here.

When is a certified manufactured/mobile home installer required?

Does a person have to be certified to work on their own home?

No. A homeowner may do work on their own residence. The homeowner may have friends or family help with the installation. However, if the homeowner pays anyone to do any part of the installation work, that person must be certified.
Are individuals and companies who receive pay to install manufactured homes required to obtain a special license or certification?

Yes. Revised code of Washington 43.22A requires certification of manufactured home installers.
Is installer certification required of a manufactured/mobile home park owner or dealer installing homes intended for sale or rental?

Yes.
Can more than one certified installer be involved in installing a mobile or manufactured home?

A certified installer is required to be on site at all times during each phase of installation. There may be different certified installers for each phase of installation. There is no requirement that the same certified installer supervise an installation from start to finish.

However, if two or more certified installers perform different aspects of the installation, one certification tag is required for each installer. For more information, see note below regarding tags.
What types of M/MH installation work require a certified installer?

Installation work requiring a certified manufactured home installer is:

Construction of the foundation system, including building forms for concrete.
Setup and assembly.
Installing the support piers.
Installing earthquake resistant bracing systems.
Connection to the foundation system and support piers.
Re-leveling of the home.
Installing skirting of any kind, decorative or load-bearing.
Connections to the on-site water and sewer systems for normal operation of the home.
Installing ground anchors.
Service work to the home that falls under the definition of manufactured home installation.

Installer certification is not required for licensed plumbers or electricians working within the scope of their license.

Expand/collapse What types of M/MH installation work do not require a certified installer?

Site preparation such as grading and excavation.
Sewer and water connections outside of the building site.
Pouring concrete into forms.
Painting and drywall finishing.
Carpet installation.
Specialty trades responsible for constructing accessory structures such as garages, carports and decks.
Specialty work performed by a licensed plumber or electrician that falls within the scope of their license.

Expand/collapse How do I know if an installer has a current certification?

Ask to see their card or certificate. Certified manufactured home installers are provided a certificate and wallet card containing their Washington Installer certification number and expiration date.
Contact The Department of Labor & Industries or check the certified installer list available on our Web site.

Certified Installer Tag Requirements

Are certified installers required to post special tags on the M/MH being installed?

Yes. Since July 1, 2003, certified manufactured home installers must place a red metallic installer certification tag on each home they install prior to inspection by the local jurisdiction. The tag must list all installation work performed by the certified installer.
If two or more certified installers perform different aspects of the installation, one tag is required for each installer. Example: If one installer sets the forms and pours the concrete runners and another installer performs all other installation work, there should be two tags affixed to the home.

Who issues installer certification tags?

L&I issues tags only to certified installers.

Where should the installer certification tag be located?

WAC 296-150I-0160 requires installer certification tags to be placed directly above or below the HUD certification label, or temporarily located in plain sight within three feet of the home’s front entry.

Who may remove an installer certification tag?

Installer certification tags shall be removed only by the homeowner following final approval of the installation of the home by the local enforcement agency.

For more information:

RCW 43.22 Sections 335-495 - Manufactured/mobile homes, factory-assembled structures. (apps.leg.wa.gov)
RCW 43.22A - Mobile and Manufactured Home Installation. (apps.leg.wa.gov)
WAC 296-150I - Manufactured Home Installer Training and Certification Program, Installation Code. (apps.leg.wa.gov)
WAC 296-150M - WA Manufactured Home Code. (apps.leg.wa.gov)

State Code for Mobile/Manufactured Home Installation

Q: What does the state code for installing mobile/ manufactured homes require?

A: WAC 296-150I, Sections 0310 through 0370, states the requirements for installing homes in Washington. Anyone installing a home in Washington State must follow the requirements of the WAC.

New Homes: Must be installed according to the home manufacturer’s instructions or the specific instructions of an engineer or architect licensed in this state. Specific instructions of an engineer or architect need not address the entire installation. The manufacturer’s installation instructions would be used for other installation aspects.
When an aspect of the installation is not covered by either the manufacturer's installation instructions or the instructions of a licensed engineer or architect, the installation shall comply with the requirements of WAC 296-150I-0310.
Relocated Homes: If the home manufacturer’s original installation instructions are unavailable, relocated homes may be installed according to the specifications of the American National Standard Institute (ANSI) A225.1 or the specific instructions of an engineer or architect licensed in Washington State. For information on where to obtain a copy of ANSI A225.1, contact the Department of Labor & Industries, Factory Assembled Structures, toll-free automated services line at 1-800-647-0982 (Option 5).

Q: Where can I find a complete list of the installation requirements of WAC 296-150I?

A: You can access the complete WAC 296-150I here. Additional copies can be obtained by contacting the Department of Labor & Industries, Factory Assembled Structures, toll-free automated services line at 800-647-0982 (Option 5).

For more information:

Local Jurisdiction (City or County) Mobile or Manufactured Home Installation Requirements

Is an inspection required for mobile or manufactured home installations?

Yes. The local jurisdiction issuing the placement permit is required to inspect MH installations. RCW 43.22.440 requires counties and cities to enforce manufactured home installation rules and charge fees in the same manner the state building code is enforced, including site preparation.

Does a local jurisdiction have any control over how and to what specifications a manufactured home is built?

No. Manufactured homes are built in a factory to the Federal Manufactured Home Construction and Safety Standards, HUD Code 3280.

If a manufactured home is being altered in anyway, is a special permit required?

Usually. Additions or changes to the home’s structure, such as installation and replacement of furnaces, wood stoves, electrical or plumbing systems, etc., are alterations to be permitted and inspected by the Department of Labor & Industries. WAC 296-150M. Please contact us for more information on alterations.

Does the local inspector receive a copy of the installation instructions for inspection purposes?

WAC 296-150I-0380 requires installation instructions to be placed under the home and to be returned to such place upon completion of inspection.
- Prior to skirting - the instructions are to be located between the I-beam and the bottom board within five feet of the main electrical feeder.
- After skirting – the instructions are to be located between the I-beam and the bottom board within five feet of the access opening.

Can the local jurisdiction set special installation requirements?

Yes, according to WAC 296-150I, Sections 0300 and 0340, local jurisdictions may impose requirements for:
- Installation of homes in floodplains;
- Homes installed in hazardous areas
- Requirements for earthquake protection
- Frost-line depth
- Soil-bearing capacity
- Noise control
- Automatic sprinkler systems for fire protection
- Local snow and wind load requirements. NOTE: All structures in the jurisdiction must be required to meet the same requirements and options for meeting those requirements must be given.
Example: According to WAC 296-150I-0300, if the local roof snow load requirement is set at 50 psf, the local jurisdiction may require the home to have a ramada, snow removal plan, or some other option – the jurisdiction may not require the home to be built with a 50 psf roof load.

Can local jurisdictions set special requirements for plumbing, electrical, or smoke detectors included in the home’s construction?

No. Plumbing systems, electrical systems, and smoke detectors are covered by the Federal HUD Code and are designed and built in the factory according to the HUD Code. The HUD Code does not cover plumbing and electrical outside of the home’s construction, such as electrical and plumbing supply to the home site.

Who has jurisdiction over auxiliary structures such as carports, garages, etc?

Auxiliary structures are built to the building code in effect at the time and governed by the local jurisdiction. To avoid requiring an alteration permit and inspection by L&I, they must be self-supporting and not use any of the mechanical systems of the home. They may be flashed to the home. Questions regarding whether a building is an auxiliary structure vs. alteration may be directed to the Department of Labor & Industries, Factory Assembled Structures.

Is the local jurisdiction required to verify that testing of water lines, waste lines, gas lines and electrical systems has been performed?

Yes. If the instructions used to install the home require testing of a particular system, WAC 296-150I-0310 requires the local inspector to verify that the individual installing that system has performed the test.

May the local jurisdictions require a specific foundation design or anchoring method be used?

No. WAC 296-150I in Section 0300 (2)(a) prohibits local jurisdictions from dictating a foundation design and construction which is built according to either the manufacturer’s installation instructions or a design created by an engineer or architect licensed in Washington. The WAC in Section 0310 (c) states that local jurisdictions may not prescribe anchoring methods.

Can local jurisdictions adopt additional requirements to protect manufactured homes in hazardous areas?

Yes. WAC 296-150I-0340 (2)(b), local jurisdictions may set a requirement for earthquake protection. Many professionally designed earthquake resistant systems exist on the market today.

Labor & Industries (L&I), Washington State

Factory-Assembled Structures

M/M Home Installation Requirements

What you need to know about installing a mobile or manufactured home

For more information:

Can homeowners install their own mobile/ manufactured home?

For more information:

When is a certified manufactured/mobile home installer required?

Certified Installer Tag Requirements

For more information:

State Code for Mobile/Manufactured Home Installation

For more information:

Local Jurisdiction (City or County) Mobile or Manufactured Home Installation Requirements

For more information: