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(1) The department adopts and incorporates by reference the International Mechanical Code, 2021 edition, published by the International Code Council, unless another edition is specifically stated, together with the following amendments:

(a) Subsection 102.8, Referenced Codes and Standards, is modified by adding the following: "Any reference to a separate specialty building regulation, by title, either in this subsection or elsewhere in this code, shall be considered deleted and replaced with the title of the model code adopted by the department and in effect at the time."

(b) All references to the International Plumbing Code shall be deleted and replaced with the Uniform Plumbing Code.

(c) Subsection 101.2 is amended to delete Exception 1 in its entirety.

(d) The fees established in Subsection 106.5.2 are as follows:

"(1) The mechanical cost shall be the cost to the owner of all labor charges and all mechanical materials and equipment installed as part of the mechanical system. The cost of the plumbing system, which is covered by the Uniform Plumbing Code, is not to be included.

"(2) The mechanical permit fees are calculated as follows:


Cost of Mechanical System

Mechanical Permit Fee

$0 - $10,000

$48 for first $1000 plus $14 for each additional $1000 or fraction thereof, to and including $10,000

$10,001 - $50,000

$166 for first $10,000 plus $9 for each additional $1000 or fraction thereof, to and including $50,000


$514 for first $50,000 plus $6 for each additional $1000 or fraction thereof.


(e) Section 108 of the International Mechanical Code will be left as is for use by certified cities, counties, and towns. The department will use 50-60-109 and 50-60-110, MCA, in cases requiring prosecution, in lieu of Section 108. When a person fails to submit required plans, obtain a permit, correct plans or comply with an order of the department, the department will, as authorized by 50-60-109, MCA, seek injunctive relief.

(f) Section 109 of the IMC will be left as is for use by certified cities, counties, or towns, which by 50-60-303, MCA, must provide an appeal procedure. Cities, counties, and towns may use a board of appeals created in accordance with Section 113 of the IBC to serve as their boards of appeal. The department and state of Montana, however, will use the applicable provisions of the Montana Administrative Procedure Act in all cases of appeal, in lieu of Section 109.

(g) Chapter 10 is deleted in its entirety.

(h) Table 403.3.1.1 is amended by the addition of a footnote "i". Footnote "i" is to be referenced in the table at, "Private Dwellings, Single and Multiplei". The footnote at the end of the table should be as follows: "i. Every dwelling unit shall have installed a minimum 100 CFM exhaust fan controlled by either an automatic timer or humidistat. Structures built to the provisions of the International Residential Code may provide mechanical ventilation per Section M1505 of the International Residential Code."

(i) Subsection 307.3, Condensate pumps, is modified by adding the following exception at the end: "Exception: A water sensor with audio alarm may be substituted for an appliance/equipment disconnect to allow for continued operation of the appliance/equipment."

(j) Subsection 506.5.2, Pollution-control units, is amended to state as follows: "506.5.2 Pollution-control units. When pollution-control units are required by the authority having jurisdiction, the installation shall be in accordance with the manufacturer's installation instructions and all of the following:"

(k) Subsection 1101.10, Locking access port caps, is modified by adding the following: "This subsection shall not apply to single-family dwellings."

(2) The department shall not enforce the IMC in buildings exempted from state building codes by 50-60-102, MCA. Cities, counties, and towns that have made the state building regulations applicable to buildings exempt from state enforcement, except for mines and buildings on mine property regulated under Title 82, chapter 4, MCA, may enforce within their jurisdictional areas the International Mechanical Code as adopted by those units of government.

(3) As specified in 76-2-412, MCA, mechanical codes which are not applicable to residential occupancies may not be applied to a community residential facility serving eight or fewer persons or to a day care home serving 12 or fewer children.

(4) The purpose of this code is to provide minimum standards to safeguard life or limb, health, property, and public welfare by regulating and controlling the design, construction, installation, quality of materials, location, operation, and maintenance of heating, ventilating, cooling, refrigeration systems, incinerators, and other miscellaneous heat-producing appliances.

(5) No mechanical permit shall be issued for a building or structure, under the jurisdiction of the department, until the building permit has first been issued for that building or structure.

(6) The IMC adopted by reference in (1) is a nationally recognized model code setting forth minimum standards and requirements for certain mechanical installations. A copy of the IMC may be obtained from the International Code Council at www.ICCSafe.org


History: 50-60-203, MCA; IMP, 50-60-102, 50-60-103, 50-60-109, 50-60-201, 50-60-203, 50-60-303, MCA; NEW, 2004 MAR p. 571, Eff. 3/12/04; AMD, 2006 MAR p. 567, Eff. 2/24/06; AMD, 2007 MAR p. 112, Eff. 1/26/07; AMD, 2010 MAR p. 1733, Eff. 7/30/10; AMD, 2014 MAR p. 2776, Eff. 11/7/14; AMD, 2019 MAR p. 2242, Eff. 12/7/19; AMD, 2022 MAR p. 911, Eff. 6/11/22.

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