Mont. Admin. R. 24.301.154 - INCORPORATION BY REFERENCE OF INTERNATIONAL RESIDENTIAL CODE
(1) The
International Residential Code (IRC) is a nationally recognized model code
setting forth minimum standards and requirements for detached one- or
two-family dwellings and multiple single-family dwellings (townhouses) not more
than three stories above grade in height, and their accessory structures. The
IRC also provides a framework for program administration.
(2) The department adopts and incorporates by
reference the International Residential Code, 2021 edition, referred to as the
International Residential Code or IRC, together with:
(a) Appendix Q, Tiny Houses. Appendix Q may
be adopted by a certified city, county, or town building code jurisdiction.
Tiny houses do not meet the building code requirements for commercial or
business occupancy and are therefore prohibited for these types of uses. The
department will apply Appendix Q to factory-built buildings which meet the
definition of a tiny house as having 400 square feet or less in floor area
excluding lofts, and which are intended to be mounted on a permanent foundation
and used as a single-family dwelling.
(b) Appendix S, Strawbale Construction.
Appendix S may be adopted by a certified city, county, or town building code
jurisdiction. The department shall not apply or enforce Appendix S.
(c) Appendix F, Radon Resistant New
Construction. Appendix F may be adopted by a certified city, county, or town
building code jurisdiction. The department shall not apply or enforce Appendix
F.
(3) Chapters 11
through 14, inclusive, are deleted in their entirety and chapters 16 through
43, inclusive, are deleted in their entirety. Chapter 15, Exhaust Systems, is
adopted as an alternative to the International Mechanical Code for exhaust
systems only. All other requirements for mechanical systems in detached one- or
two-family dwellings and multiple single-family dwellings (townhouses) not more
than three stories above grade in height, and their accessory structures, shall
be found in the latest adopted edition of the International Mechanical
Code.
(4) Subsection R102.7,
Existing Structures, is deleted and replaced with the following: "The legal
occupancy of any structure existing on the date of this code shall be permitted
to continue without change, except as is specifically covered in this code or
the legally adopted fire code as administered by the fire authority having
jurisdiction."
(5) Subsection
R301.6, Roof Load, is deleted and replaced with the following: "Snow loads
shall be determined by the building official. In areas of the state outside of
certified city, county, or town jurisdictions, the design snow load shall be
based on the ground snow loads developed in "Snow Loads for Structural Design
in Montana", Civil Engineering Department , Montana State University, 2004
revised edition. The minimum design roof snow load after allowed reductions
shall be 30 psf unless justified by a Montana licensed design professional to
the satisfaction of the building official. Coefficients and factors other than
those specified in the building code may be used when justified by a Montana
licensed design professional to the satisfaction of the building
official."
(6) Subsection 302.2.2,
Common walls, delete "Chapters 34 through 43" and replace with "the adopted
electrical code in ARM Title 24, chapter 301, subchapter 4."
(7) Subsection 302.2.4, Structural
Independence, delete exception number five and replace with the following:
"Townhouses separated by a common two-hour fire-resistance-rated wall as
provided in Section R302.2."
(8)
Subsection R302.13, Fire Protection of Floors, is deleted in its
entirety.
(9) Subsection 309.5,
Fire Sprinklers, is deleted in its entirety.
(10) Subsection R311.7.5.1, Risers, is
amended to allow a maximum riser height of 8 1/4 inches.
(11) Subsection R311.7.5.2, Treads, is
amended to allow a minimum tread depth of nine inches. (12) Subsection 312.1.1,
Where Required, delete the first sentence and replace with the following:
"Guards shall be located along open-sided walking surfaces, including stairs,
ramps, and landings, that are located more than 30 inches measured vertically
to the floor or grade below."
(13)
Section R313, Automatic Fire Sprinkler Systems, is deleted in its
entirety.
(14) Subsection R403.1.1,
Minimum size, is modified to add the following: "Exception: The building
official may allow footings to be designed in accordance with Section R403 of
the 2012 IRC or may allow footings engineered by a design
professional."
(15) Subsection
403.1.6, Foundation Anchorage, is deleted in its entirety and replaced with the
following: "Where wood sill and sole plates are supported directly on
continuous foundation walls or monolithic slabs with integral footings required
by the provisions of this code, they shall be anchored to the foundation in
accordance with this section. Cold-formed steel floor and wall framing shall be
anchored to the foundation in accordance with Section R505.3.1 or R603.3.1.
Wood sole plates at all exterior walls, wood sole plates of braced wall lines
at building interiors on monolithic slabs with integral footings and all wood
sill plates shall be anchored to the foundation with minimum one-half inch
diameter anchor bolts spaced a maximum of six feet on center or approved
anchors or anchor straps spaced as required to provide equivalent anchorage to
the one-half inch diameter anchor bolts. Bolts shall extend a minimum of seven
inches into concrete or grouted cells of concrete masonry units. A nut and
washer shall be tightened on each anchor bolt. There shall be a minimum of two
bolts per plate section with one bolt located not more than 12 inches or less
than seven bolt diameters from each end of the plate section. Interior bearing
wall sole plates on monolithic slab foundations with integral footings that are
not part of a braced wall line shall be positively anchored with approved
fasteners. Sill plates and sole plates shall be protected against decay and
termites where required by sections R317 and R318.
Exceptions:
1.
Walls 24 inches total length or shorter connecting offset braced wall panels
shall be anchored to the foundation with a minimum of one anchor bolt located
in the center third of the plate section and shall be attached to adjacent
braced wall panels at corners as shown in item 8 of Table R602.3(1).
2. Connections of walls 12 inches total
length or shorter connecting offset braced wall panels to the foundation
without anchor bolts shall be permitted. The wall shall be attached to adjacent
braced wall panels at corners as shown in item 8 of table R602.3(1)."
(16) Subsection R405.1 is amended
by adding the following: "A drainage system is not required when continuous
rain gutters are installed incorporating drain extensions which divert storm
water a minimum of six feet (1.83 m) away from the foundation and grading is
done in accordance with R401.3. A drainage system may be required where high
water tables are known to exist or geological conditions which require a soils
engineering report, performed in accordance with R401.4, specify the need for
foundation drainage."
(17)
Subsection 602.10, Wall Bracing, delete the first sentence and replace with the
following: "Building shall be braced in accordance with this section or, when
applicable, Section R602.12, or the most current version of APA System Report
SR-102 as an alternate method.
(18)
Subsection R602.10.10, Cripple Wall Bracing, add the following sentence: "The
distance between adjacent edges of braced wall panels shall be 20
feet."
(19) Subsection R703.4,
Flashing, delete the first paragraph in its entirety and replace with the
following: "Flashing shall be provided in accordance with this section to
prevent entry of water into the wall cavity or penetration of water to the
building structural framing components. Flashing shall extend to the surface of
the exterior wall finish or to the water-resistive barrier for drainage and
shall be installed at all of the following locations:"
Further, delete Number "1", number "1.1", number "1.2", and number "1.3" in their entirety and replace with the following: "1. Exterior window and door openings."
Number "2" through "7" remain unchanged in Subsection R703.4.
(20) Add new
subsection as follows: "R703.4.1, Flashing Materials. Approved flashing
materials shall be corrosion-resistant. Self-adhered membranes used as flashing
shall comply with AAMA 711. Pan Flashing shall comply with Subsection R703.4.2.
Installation of flashing materials shall be in accordance with Subsection
R703.4.3.
(21) Add new subsection
as follows: "R703.4.2, Pan Flashing. Pan Flashing installed at the sill of
exterior window and door openings shall comply with this section. Pan Flashing
shall be corrosion-resistant and shall be permitted to be pre-manufactured,
fabricated, formed, or applied at the job site. Self-adhered membranes
complying with AAMA 711 shall be permitted to be used as Pan Flashing. Pan
Flashing shall be sealed or sloped in such a manner as to direct water to the
surface of the exterior wall finish or to the water-resistive barrier for
subsequent drainage."
(22) Add new
subsection as follows: "R703.4.3, Flashing Installation. Installation of
flashing materials shall be in accordance with one or more of the following
methods:
1. The fenestration manufacturer's
installation and flashing instructions.
2. The flashing manufacturer's installation
instructions.
3. Flashing details
approved by the Building Official.
4. As detailed by a Registered Design
Professional."
(23)
Appendices do not apply to a certified city, county, or town building code
jurisdiction unless specifically authorized or adopted by the department and
adopted by the certified city, county, or town building code
jurisdiction.
(24) A copy of the
International Residential Code may be obtained from the International Code
Council at www.ICCsafe.org.
Notes
AUTH: 50-60-203, MCA IMP: 50-60-102, 50-60-201, 50-60-203, MCA.
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