Cutaway of manufactured home. Modular and Other Mobile Structures

Structures that require permits

Submit plans

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

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.

Is your mobile medical unit exempt?

A unit is exempt if it has been used outside Washington as a mobile medical unit for 6 months or more. Exempt medical mobile units do not need to submit plans.

To purchase a permit for a unit exempt from plan review, visit your local office to:

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 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.

    Related Resources

    Contact Us

    • 1-800-705-1411 Option 3

    Mailing address

    Washington State Department of Labor & Industries
    Factory Assembled Structures
    PO Box 44430
    Olympia WA 98504-4430


    7273 Linderson Way SW
    Tumwater WA 98501