Montana Administrative Register Notice 24-301-350 No. 24   12/24/2020    
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                                                STATE OF MONTANA 


In the matter of the amendment of ARM 24.301.161 incorporation by reference of the International Energy Conservation Code







TO: All Concerned Persons


            1. On January 19, 2021, at 9:30 a.m., a public hearing will be held via remote conferencing to consider the proposed amendment of the above-stated rule. Because there currently exists a state of emergency in Montana due to the public health crisis caused by the coronavirus, there will be no in-person hearing. Interested parties may access the remote conferencing platform in the following ways:

            a. Join Zoom Meeting, https://mt-gov.zoom.us/j/91065323119, Meeting ID: 910 6532 3119, Passcode: 551610; or

            b. Dial by telephone, +1 406 444 9999 or +1 646 558 8656, Meeting ID:

910 6532 3119, Passcode: 551610.


            The hearing will begin with a brief introduction by department staff to explain the use of the videoconference and telephonic platform. All participants will be muted except when it is their time to speak.


            2. The Department of Labor and Industry (department) will make reasonable accommodations for persons with disabilities who wish to participate in this public hearing or need an alternative accessible format of this notice. If you require an accommodation, contact the Building Codes Program no later than 5:00 p.m., on January 12, 2021, to advise us of the nature of the accommodation that you need. Please contact Traci Collett, Building Codes Program, 301 South Park Avenue, P.O. Box 200517, Helena, Montana 59620-0517; telephone (406) 841-2016; Montana Relay 1 (800) 253-4091; TDD (406) 444-2978; facsimile (406) 841-2050; or buildingcodes@mt.gov.


            3. The rule proposed to be amended is as follows, stricken matter interlined, new matter underlined:


            24.301.161 INCORPORATION BY REFERENCE OF INTERNATIONAL ENERGY CONSERVATION CODE (1) The Department of Labor and Industry adopts and incorporates by reference the International Code Council's International Energy Conservation Code, 2012 2018 Edition, referred to as the International Energy Conservation Code, unless another edition is specifically stated, together with the following Appendix and amendments:

            (a) and (a)(i) remain the same.

            (b) Subsections C104.2 C105.2 and R104.2 R105.2, Required Approvals Inspections, are deleted in their entirety when the code is used by the Building Codes Bureau Program of the Department of Labor and Industry. It remains undeleted and available for use for certified local governments using the code.

            (c) remains the same.

            (d) Table 402.1.1 R402.1.2, INSULATION AND FENESTRATION REQUIREMENTS BY COMPONENT, is amending requirements for climate zone "6" as shown below in the table:













Framed Wall



0.32 0.30




21 or 13+10(h)


Mass Wall









& Depth

Crawl Space






10, 4 ft



            (e) Table R402.1.3 R402.1.4, EQUIVALENT U-FACTORS, is amending requirements as shown below in the table:

Climate Zone







Frame Wall


Mass Wall




Base-ment Wall


Crawl Space Wall














            (f) Subsection R402.2.2, Ceilings Without Attic Spaces, is deleted and replaced with the following: "Where Section 402.1.1 402.1.2 would require insulation levels above R-30 and the design of the roof/ceiling assembly does not allow sufficient space for the required insulation, the minimum required insulation for such roof/ceiling assemblies shall be R-30. This reduction of insulation from the requirements of Section 402.1.1 402.1.2, shall be limited to 250 square feet or ten percent of the total insulated ceiling area, whichever is less. This reduction shall not apply to the U-factor alternative approach in Section 402.1.3 402.1.4, and the total UA alternative in Section 402.1.4 402.1.5."

            (g) Subsection R402.2.9 R402.2.11, Crawl Space Walls, is deleted and replaced with the following: "As an alternative to insulating floors over crawl spaces, crawl space walls shall be permitted to be insulated when the crawl space is not vented to the outside. Temporary crawl space vent openings are allowed during construction for crawl spaces that have insulated crawl space walls. These temporary crawl space vent openings shall be closed, sealed, and insulated to the same R-value of the surrounding crawl space wall insulation once construction is complete and prior to the time that the final building inspection would occur. Crawl space wall insulation shall be permanently fastened to the wall and shall extend downward from the floor, the entire height of the crawl space wall. Exposed earth in unvented crawl space foundations shall be covered with a continuous Class I vapor retarder. All joints of the vapor retarder shall overlap six inches and be sealed or taped. The edges of the vapor retarder shall extend at least six inches up the stem wall and shall be attached and sealed to the stem wall."

            (h) Subsection R402.4.1.2, Testing, is deleted and replaced with the following: The building or dwelling unit shall be tested and verified as having an air leakage rate of not exceeding four air changes per hour in Climate Zone 6. Testing shall be conducted with a blower door at a pressure of 0.2 inches w.g. (50 Pascals). Where required by the code official, testing shall be conducted by an approved party. A written report of the results of the test shall be signed by the party conducting the test and provided to the code official. Testing shall be performed at any time after creation of all penetrations of the building thermal envelope. The requirements of testing found in subsection R402.4.1.2 will not be mandatory until one year following the final adoption of this rule. Buildings or dwelling units issued a building permit by a code official prior to this testing becoming required shall not be required to perform testing under subsection R402.4.1.2. During testing:

            (i) through (vi) remain the same.

            "(vii) HVAC ducts shall not be sealed supply and return registers, where installed at the time of test, shall be fully open.

            (i) Subsection R403.2.2, Sealing (Mandatory). Delete the existing 2. found beneath, "duct tightness shall be verified by either of the following:" and replace the existing 1. with the following:

            "Postconstruction test: Leakage to the outside of a condition space or total leakage shall be less than or equal to four cfm per 100 square feet of conditioned floor area when tested at a pressure differential of 0.1 inches w.g. across the entire system, including the manufacturer's air handler enclosure. All register boot shall be taped or otherwise sealed during the test.

            Exception: The duct tightness testing is not required for ducts and air handlers located entirely within the building thermal envelope.

            (j) (i)  Subsection R403.2.3, R403.3.5, Building Cavities, is deleted in its entirety and replaced with: "Building framing cavities shall not be used as supply ducts." Exception:  Building framing cavities may be used for return ducts if there is no atmospherically vented furnace, boiler, or water heater located in the house outside of a sealed and insulated room that is isolated from inside the thermal envelope and if the duct system has been tested as having a maximum total leakage not greater than 4 cfm/SF.  The room walls, floor, and ceilings shall be insulated in accordance with the basement wall requirements of Table R402.1.2.

            (k) remains the same but is renumbered (j).

            (l) Table R405.5.2(1) SPECIFICATIONS FOR THE STANDARD REFERENCE AND PROPOSED DESIGNS, amend the table as shown below:


Building Component

Standard Reference Design

Proposed Design











Untested distribution systems:

DSE = 0.88


Tested Ducts: Leakage rate to outside conditioned space as specified Section R403.2.2(1)


Tested duct Location:

Conditioned space


Tested duct Insulation: in accordance with Section R403.2.1


Untested distribution systems:

DSE from Table R405.5.2(2)


Tested Ducts: Tested Leakage rate to outside conditioned space


Duct Location: As proposed


Duct Insulation: As proposed


            (k)  Appendix RA, Solar-Ready Provisions–Detached One- and Two-Family Dwellings and Townhouses.  Appendix RA may be adopted by a certified city, county, or town building code jurisdiction.  The department shall not apply or enforce Appendix RA.

            (2) remains the same.

            (a) The department encourages owners, design professionals, and builders to voluntarily implement greater levels of energy efficiency in building design and construction than those required by the International Energy Conservation Code. Information regarding voluntary building standards for greater levels of energy efficiency can be obtained from the department by contacting the department at the address listed in (3) Department of Labor and Industry, Building Codes Program, P.O. Box 200517, Helena, MT 59620-0517, by telephone at 406-841-2053 406-841-2056, or at the department's web site, http://bsd.dli.mt.gov/bc/bs_index.asp http://bsd.dli.mt.gov/building-codes-permits.

            (3) The International Energy Conservation Code is a nationally recognized model code for energy efficient construction of buildings. A copy of the International Energy Conservation Code may be obtained from the Department of Labor and Industry, Building Codes Bureau, P.O. Box 200517, Helena, MT 59620-0517, at cost plus postage and handling. A copy may also be obtained by writing to the International Code Council, 4051 West Flossmoor Road, Country Club Hills, IL 60478-5795, or visiting the International Code Council web site at www.ICCsafe.org


            AUTH: 50-60-203, 50-60-803, MCA

            IMP:    50-60-201, 50-60-203, 50-60-803, MCA


REASONAt the end of 2019, the Building and Commercial Measurements Bureau, Business Standards Division, Department of Labor and Industry (department) amended several administrative rules to adopt and incorporate by reference new editions of numerous nationally recognized building codes, with stated exceptions. The department also amended certain rules to coincide with the adoption and incorporation by reference of these building codes. At that time, the department concluded it was necessary to obtain additional stakeholder input prior to adopting the 2018 Edition of the International Energy Conservation Code (IECC) and is therefore proceeding with those changes now.

            The department is amending (1)(a) through (h) to reflect the adoption of and changes in the 2018 Edition of the International Energy Conservation Code (IECC). The rule amendments are reasonably necessary in (1)(i) through (k) to reflect changes instituted by the Building Codes Advisory Council as related to changes made in the 2018 Edition of the IECC.

            The department is amending (2)(a) and (3) to reflect the program's current contact information and where to obtain a copy of the IECC from the ICC web site.


            4. Concerned persons may present their data, views, or arguments either orally or in writing at the hearing. Written data, views, or arguments may also be submitted to the Building Codes Program, 301 South Park Avenue, P.O. Box 200517, Helena, Montana 59620-0517, by facsimile to (406) 841-2050, or e-mail to buildingcodes@mt.gov, and must be received no later than 5:00 p.m., January 21, 2021.


            5. An electronic copy of this notice of public hearing is available at http://bsd.dli.mt.gov/building-codes-permits (department and program's web site). Although the department strives to keep its web sites accessible at all times, concerned persons should be aware that web sites may be unavailable during some periods, due to system maintenance or technical problems, and that technical difficulties in accessing a web site do not excuse late submission of comments.


            6. The department maintains a list of interested persons who wish to receive notices of rulemaking actions proposed by this program. Persons who wish to have their name added to the list shall make a written request that includes the name, e-mail, and mailing address of the person to receive notices and specifies that the person wishes to receive notices regarding all Building Codes Program administrative rulemaking proceedings or other administrative proceedings. The request must indicate whether e-mail or standard mail is preferred. Such written request may be sent or delivered to the Building Codes Program, 301 South Park Avenue, P.O. Box 200517, Helena, Montana 59620-0517; faxed to the office at (406) 841-2050; e-mailed to buildingcodes@mt.gov; or made by completing a request form at any rules hearing held by the agency.


            7. The bill sponsor contact requirements of 2-4-302, MCA, do not apply.


            8. Regarding the requirements of 2-4-111, MCA, the department has determined that the amendment of ARM 24.301.161 will not significantly and directly impact small businesses.

            Documentation of the department's above-stated determination is available upon request to the Building Codes Program, 301 South Park Avenue, P.O. Box 200517, Helena, Montana 59620-0517; telephone (406) 841-2016; facsimile (406) 841-2050; or to buildingcodes@mt.gov.


            9. Traci Collett has been designated to preside over and conduct this hearing.






Darcee L. Moe

Rule Reviewer


Brenda Nordlund, Acting Commissioner



            Certified to the Secretary of State December 15, 2020.


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