Oklahoma Administrative Code › Title 748 - Oklahoma Uniform Building Code Commission › Chapter 20 - Adopted Codes › Subchapter 6 - IRC[®] 2018 › Section 748:20-6-53 - Appendix X, Residential Tornado Provisions

Current through Vol. 41, No. 20, July 1, 2024
(a)
				This appendix has been newly created and entitled "Residential Tornado
				Provisions." The provisions contained in this appendix are not mandatory unless
				specifically referenced in the adopting ordinance or order.
(b) X101 Scope. This section heading has been
				added to specify the sections of this appendix that deal with the Scope of the
				appendix. This section header has been added to read: X101. Scope.
(1) Section X101.1 General. This section has
				been added to clarify the provisions shall be applicable for new construction.
				This section has been added to read: X101.1 General. These provisions shall be
				applicable for new construction where residential tornado provisions are
				required. This appendix provides prescriptive based requirements for
				construction of a residential structure meeting or exceeding a 135-mph wind
				event corresponding to an EF-2 tornado rating. The single most important
				objective in protecting a structure against high wind is achieving a continuous
				load path from the roof to the foundation. Based on the findings of studies and
				failures associated with various construction types, a group of 11 building
				practices (each associated with a different aspect of the structure) are
				summarized in this section.
(2)
				Section X101.2 Application. This section has been added to clarify the
				administrative provisions of this appendix are applicable in the administrative
				and building planning and construction requirements in Chapters 1 through 10 of
				this code. The section has been added to read: X101.2 Application. In addition
				to the general administration requirements of Chapter 1, the administrative
				provisions of this appendix shall also apply to the building planning and
				construction requirements of Chapters 1 through 10.
(3) Section X101.3 Wind design criteria. This
				section has been added to clarify that if Section R301.2.1 is modified, the
				buildings and portions thereof shall be constructed in accordance with the code
				and the ultimate wind speed design of 135 mph. This section has been added to
				read: X101.3 Wind design criteria. Modifying section R301.2.1 buildings and
				portions thereof shall be constructed in accordance with the wind provisions of
				this code using the ultimate design wind speed 135 mph.
(4) Section X101.4 Lumber sheathing. This
				section has been added to address the permitted forms of lumber sheathing. This
				section has been added to read: X101.4 Lumber sheathing. Only OSB or plywood
				sheathing is permitted. Dimensional lumber sheathing may not be used. Allowable
				spans and attachment for lumber used as roof or exterior wall sheathing shall
				conform to the following:
(A) X101.4.1 Sixteen
				Inch Framing. For rafter, stud, or beam spacing of 16 inches, the minimum
				nominal sheathing panel thickness will be 7/16 inch, the minimum wood
				structural panel span rating 24/16, to be nailed with 8d ring shank (0.131 inch
				x 2.5 inch) or 10d (0.148 inch x 3 inch) nails on 4 inches on center along the
				edges and 6 inches on center in the field.
(B) X101.4.2 Twenty-four Inch Framing. For
				rafter, stud or beam spacing of 24 inches, the minimum nominal sheathing panel
				thickness will be 23/32 inch, the minimum wood structural panel span rating
				24/16 to be nailed with 8d ring shank (0.131 inch x 2.5 inch) or 10d (0.148
				inch x 3 inch) nails on 4 inches on center along the edges and 4 inches on
				center in the field.
(5)
				Section X101.5 Ceiling joist and rafter connections. This section has been
				added to require ceiling joists and rafters to be nailed to each other in a
				manner to achieve a connection that can transfer a 500-pound force in both
				compression and tension across the connections. This section has been added to
				read: X101.5 Ceiling joist and rafter connections. In addition to the
				provisions of Chapter 8, ceiling joists and rafters shall be nailed to each
				other in a manner to achieve a connection that can transfer a 500-pound force
				in both compression and tension across the connection.
(6) Section X101.6 Rafter uplift resistance.
				This section has been added to require individual rafters to be attached to
				supporting wall assemblies by connections capable of resisting uplift forces of
				500 pounds. This section has been added to read: X101.6 Rafter uplift
				resistance. Individual rafters shall be attached to supporting wall assemblies
				by connections capable of resisting uplift forces of 500 pounds.
(7) Section X101.7 Gable end walls. This
				section has been added to clarify connections and sheathing for gable end
				walls. This section has been added to read: X101.7 Gable end walls. Gable end
				walls will be sheathed per X101.4 and will have connections to both a.)
				supporting wall assemblies and b.) roof framing by connections capable of
				resisting uplift forces of 500 pounds in both compression and tension across
				the connection.
(8) Section X101.8
				Exterior wall bracing. This section has been added to clarify sheathing methods
				to be utilized to brace exterior walls and prohibit intermittent bracing on
				exterior walls. This section has been added to read: X101.8 Exterior wall
				bracing. Only continuous sheathing methods per R602.10.4.2 may be used to brace
				exterior walls. Frame garage doors using the sheathed portal frame method
				CS-PF. Lumber sheathing and attachment per X101.4. Any form of intermittent
				bracing is not allowed on an exterior wall. Intermittent bracing may only be
				used for interior braced wall lines.
(9) Section X101.9 Multi story construction.
				This section has been added to require nailing upper and lower story wall
				sheathing to a common rim board. This section has been added to read: X101.9
				Multi story construction. Nail upper and lower story wall sheathing to common
				rim board in order to maintain continuity between stories.
(10) Section X101.10 Wood floor above crawl
				space construction. This section has been added to require extending structural
				wood sheathing to lap the sill plate. This section has been added to read:
				X101.10 Wood floor above crawl space construction. Extend structural wood
				sheathing to lap the sill plate. Nail to sill plate at 4 inches on center along
				the edges. Nail to rim board if present with 8d ring shank (0.131 inch x 2.5
				inch) or 10d (0.148 inch x 3 inch) nails at 4 inches on center along both the
				top and bottom edges of the rim board.
(11) Section X101.11 Garage Doors. This
				section has been added to require garage doors to be rated for 135 mile per
				hour winds. This section has been added to read: X101.11 Garage Doors. Garage
				doors are to be wind rated to 135 mph.