Factory-Built Buildings Permits

Apply for a Factory Built Building Permit

Online Factory Built Building Permit
Print Paper Applications
Factory Built Building Application  Insignia Application
Third Party Inspector Certification Form


Please read below regarding permit requirements before applying. If you have questions about the process please email  the Factory Built Building Program or call (406) 841-2056.

Factory-Built Building (FBB) is a factory assembled structure(s) equipped with the necessary service connections and designed to be used with a permanent foundation.

No person(s) can sell or offer for sale within Montana any factory-built building(s) unless the unit(s) and its components, systems, and appliances have been constructed and assembled in accordance with the standards as defined in Title 50, Chapter 60of the Montana Codes Annotated. Manufacturers approved to sell or offer for sale factory built buildings can be found on the list of approved FBB Manufacturers

All units manufactured or delivered prior to sale, sold, or offered for sale need a factory-built building insignia and, if applicable, the insignia of a reciprocal state or the certified third party inspection agency.

Factory-built buildings shall meet the requirements of the latest adopted editions of the model codes.

The requirements listed in 50-60-402(1), MCA, apply to all new factory-built units, whether offered for sale, lease or rent, which are first utilized in the State of Montana, regardless of the unit's point of origin or route of delivery.

  • (FBB) means a factory assembled structure or structures equipped with the necessary service connections but not made so as to be readily movable as a unit or units and designed to be used with a permanent foundation.
  • Means an agency, which inspects and certifies, in lieu of state inspectors, that an FBB conforms to the requirements and standards set forth in Title 50, Chapter 60, Montana Codes Annotated and Title 24, Chapter 301, Administrative Rules of Montana.  Visit the Bureau’s Website at www.buildingcodes.mt.gov. for all current codes.  A Third Party Inspection Agency is not under the control or jurisdiction of any supplier, manufacturer or dealer, except by contractor for quality control and/or inspections of FBB units.  Currently approved 3rd Party Inspection Agencies are listed below.

     List of 3rd Party Inspection Agencies




    Last Updated 4/28/23
  • A manufacturer of a factory-built building may make application for a typical structural design approval prior to construction.  The following general requirements must be met:

    • Dimensioned drawings and specifications are required and they must clearly indicate the nature and extent of the work proposed.
    • An electronic copy of all documents submitted for approval are required, or one paper copy not less than 8 ½” x 11” and not more than 11" x 17'.
    • Fees must be paid as required by ARM 24.301.565 through 24.301.567.

    The following specific requirements must be met:

    • All necessary cross sections;
    • Floor, wall ceiling and roof construction details;
    • Typical connections;
    • Design live and dead loads;
    • Grade and quality of materials;
    • Substantiating calculations or test results, where required.

    A manufacturer of a factory-built building may make applications for approval of typical electrical, mechanical and plumbing equipment and installations prior to construction, which may be referenced on subsequent plans. The following letters will be used to designate typical systems: E, M, P.

  • The following electrical specifications must be set forth in the plan:

    • Type and size of feeder assembly;
    • Voltage and amperage of branch circuit panel board;
    • Branch circuit identification, amperage or over current protection device wire size and type;
    • Voltage and amperage of fixed appliances;
    • Calculations according to NFPA 70.
  • The plan may be drawn to scale or schematic.  It must set forth the following mechanical information:

    • Description of all materials, appliances, fittings, pipe, tubing, vents and ducts.
    • BTUH input rating of all fuel burning appliances;
    • Size of openings for combustion air, except where combustible air is an integral part of an approved appliance;
    • Size, length, type and location of vents and vent connectors;
    • Type, minimum dimension and gauge of air ducts;
    • Minimum free area and location of circulating air supply inlet;
    • Minimum free area and location of all air openings.
  • The plan may be drawn to scale or schematic.  It must set forth the following plumbing specifications:

    • Description of all materials, fixtures, fittings, pipe tubing, shower stalls and walls;
    • Diameter and type of pipe and tubing, and length of all trap arms;
    • Size and type of fittings;
    • Grade of drainage piping;
    • Method of securing all piping.
  • The manufacturer shall submit a manual, or shall reference an applicable manual previously reviewed by the Bureau, outlining a program of quality control concurrent with a request for plan review. The program outlined must meet the standards of and be reviewed by the Bureau.  In addition, the manufacturer shall designate a company or corporate officer or other responsible person to be responsible for the quality control program, and shall maintain records to substantiate that each unit has been inspected and complies with the plans as reviewed by the Bureau.  The Bureau may make periodic inspections and may condition the issuance of insignia on compliance with Administrative Rules by the manufacturer.

    The following specific information is required for the quality control manual:

    • Scope and purpose of the manual;
    • Inspection procedure for basic materials;
    • Material storage and stock rotation procedure;
    • Drawings and bill of material;
    • Types and frequency of product inspection;
    • Sample of inspection control form used;
    • Record-keeping procedures for quality control forms;
    • List of major pieces of production equipment;
    • Where responsibility for quality control program lies;
    • Test procedural manual, including electrical, gas line, water systems and drain/vent/plumbing fixture tests and type of test equipment used;
    • List of test equipment.

    All units manufactured or delivered prior to sale or sold or offered for sale in this state shall bear a Factory-Built Building Insignia issued by the State of Montana. 

  • The manufacturer shall make application to have their plans renewed for the following year prior to the December 31 expiration date of each.  At the time of renewal, plans which have not be changed do not require the re-submission of plans. If any changes have been made, an updated plan must be submitted.  The application shall be accompanied by the renewal fee.
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