Cutaway of manufactured home. Modular and Other Mobile Structures

Plan review by licensed professionals

Through Dec. 14, 2022, L&I has extended the opportunity to speed plan review for modular buildings, among other products. The process allows you to use an L&I-approved professional engineer or architect to review your plans. You may review this process below. 

Structures that require permits

Modular buildings: Buildings which are constructed in factories and at other offsite locations and then shipped to Washington must be approved by L&I. This includes equipment shelters that can be entered by personnel.

Temporary Worker Housing (TWH): TWH units fabricated in factories and being shipped to Washington must be inspected by L&I as they are constructed.

Recreational vehicles and park models: All RVs and Park Model RVs for sale or lease in Washington must have an L&I approval label.

Commercial coaches: Commercial coach trailers must be inspected and approved by L&I.

Submit plans

Visit or mail the plans to the L&I office nearest you.

Plan review by licensed professionals

Through Dec. 14, 2022, L&I has extended the opportunity to speed plan review for modular buildings, among other products. The process allows you to use an L&I-approved professional engineer or architect to review your plans.

Here’s how it works:

Below is a list of products included in the quick review process. Choose either an L&I-approved professional engineer, or the standard review -- which allows you to continue to file plans with the Factory Assembled Structures Program.

In either case, L&I must process all the plans. The L&I inspection process remains the same.

For all products, see further information with this Emergency Rule & Licensed Professional (LP) Information Letter.

The new process is available for the following design plan submissions:

Commercial coaches
Plan review & submittal guidelines

Factory-built housing and commercial structures
Plan review & submittal guidelines - Commercial buildings
Plan review & submittal guidelines - Residential buildings
Standard procedures for existing plans

Recreational park trailers
Plan review & submittal guidelines
Standard procedures for existing plans

Recreational vehicles 
Plan review & submittal guidelines
Standard procedures for existing plans

Conversion vendor units (food trucks) and medical units
Plan review & submittal guidelines
Standard procedures for existing plans

Note: When using this new process, you will still need to pay filing fees with L&I, besides the cost of the private architect or engineer.

Read more about the emergency rulemaking that created the process.

We apologize for the significant service delays and thank you for your patience and understanding. We sincerely hope this new procedure will help you get timely approval for your project.

Contact us 

FAS1@Lni.wa.gov
1-800-705-1411 Option 3

Mailing address
Washington State Department of Labor & Industries
PO Box 44430
Olympia WA 98504-4430

Location
7273 Linderson Way SW
Tumwater WA 98501

Mobile Medical Units

If you are building a mobile medical unit, we must approve your alteration plans, inspect your unit, and issue a permit. Use this page to determine if you have a mobile medical unit, and follow the steps outlined below to get your permit.

Find out if your mobile medical unit needs a permit and inspection

Is your vehicle a mobile medical unit?

Answer yes or no to the following questions:

  • Is the vehicle used for something other than emergency response?
  • Are medical examinations, treatments, medical or dental services or procedures provided in the vehicle?
  • Is the vehicle built on a chassis?
  • Is the vehicle designed for use at temporary locations?
  • Does the vehicle include electrical, plumbing, or gas piping systems of some sort? If the answer is “yes” to all of the questions above, then you have a mobile medical unit, and you will need to submit plans and have it inspected.

Submit plans and have your unit inspected

Here's the process for getting your mobile medical unit alteration plan approved and the work inspected and approved by us:

First, you need to create a plan and submit it to us for review

The conversion vendor unit (or mobile medical unit) plans you submit for plan review must contain enough information to determine conformance with the applicable conversion vendor and medical unit codes.

Structural: Only concentrated loads of 500 pounds or more in a 16-square-foot area need to be addressed. Compliance can be accomplished by means of WAC 296-150V-0350. This would apply to units that were either built or converted from another structure as a Vendor Unit" under WAC 296-150V. If you wish to build or convert a structure into a "Commercial Coach," please contact us at FAS1@Lni.wa.gov or 1-800-705-1411 Option 3.

Electrical: Show the general location of outlets, lights, switches, and the main distribution panel box (this may be combined with the floor plan drawing or done as a separate drawing). Include a schedule showing what the breakers in the main panel box are, including breaker sizes and what they control. Provide electrical load calculations that show the overall electrical demand in amps.

Plumbing (water): Show the locations of all sinks, holding tanks, and other plumbing fixtures. Include pipe sizes for water supply. Provide information on the operating pressure in the water supply system as well as the length of water piping from the inlet or pump to the furthest fixture.

Plumbing (drain): Show the locations of all sinks, holding tanks, and other plumbing fixtures. Include pipe sizes for drainage, waste, and vent pipes. Show the location and size of the drainage system outlet.

Mechanical: If you have gas appliances in your commercial coach, you must show the gas piping layout and size. You will be required to supply the BTU/H input requirements for all gas appliances. Show the location of the gas supply inlet or tank. Provide the type of fuel (i.e.: natural gas or propane) and the length of the piping run from the tank or inlet to the furthest appliances. If you have a heating or air conditioning appliance, you will have to show conformance to the state energy code on the forms provided.

Next, we must review and approve your plan before you start the work

In order for us to review your plan, you must submit a completed Plan Approval Request — Conversion Vendor/Medical Units form (F622-035-000) and a minimum of 2 complete sets of plans that follow the specifications listed in the form's instructions.

  • You must pay fees in accordance with the published fees schedule in WAC 296-150V-3000 for us to examine the plans for conformance to the proper building codes.
  • You will also have to purchase a Conversion Vendor & Medical Unit insignia. Fill out an Application for Insignia — Conversion Vendor/Medical Units (F623-021-000).
  • Once we review and approve your plan design, we will assign it a plan number and will return to you one copy of the plan by mail.
  • Then, we must inspect and approve the work you've done.

Note: Be sure to check with all local building departments where you plan to use your unit. Some building departments may not allow the use of conversion vendor units in their jurisdiction. You may be required to have a commercial coach in that jurisdiction.

Contact us 

FAS1@Lni.wa.gov
1-800-705-1411 Option 3

Mailing address
Washington State Department of Labor & Industries
PO Box 44430
Olympia WA 98504-4430

Location
7273 Linderson Way SW
Tumwater WA 98501