ADOPTS WITH AMENDMENTS:

International Residential Code 2015 (IRC 2015)

Part I — Administrative

Part II — Definitions

Part III — Building Planning and Construction

Part IV — Energy Conservation

Part V — Mechanical

Part VI — Fuel Gas

Part VII — Plumbing

Part VIII — Electrical

Part IX — Referenced Standards

Heads up: There are no amended sections in this chapter.

Appendix Y Residential Tornado Provisions

AMENDMENT
This section has been amended at the state or city level.
The provisions contained in this appendix are not mandatory unless specifically referenced in the adopting ordinance or order.

Section Y101 Scope

AMENDMENT
This section has been amended at the state or city level.

Y101.1 General

AMENDMENT
This section has been amended at the state or city level.
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.

Y101.2 Application

AMENDMENT
This section has been amended at the state or city level.
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.

Y101.3 Wind Design Criteria

AMENDMENT
This section has been amended at the state or city level.
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.

Y101.4 Lumber Sheathing

AMENDMENT
This section has been amended at the state or city level.
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.

Y101.4.1 Sixteen Inch Framing

AMENDMENT
This section has been amended at the state or city level.
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.

Y101.4.2 Twenty-Four Inch Framing

AMENDMENT
This section has been amended at the state or city level.
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.

Y101.5 Ceiling Joist and Rafter Connections

AMENDMENT
This section has been amended at the state or city level.
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.

Y101.6 Rafter Uplift Resistance

AMENDMENT
This section has been amended at the state or city level.
Individual rafters shall be attached to supporting wall assemblies by connections capable of resisting uplift forces of 500 pounds.

Y101.7 Gable End Walls

AMENDMENT
This section has been amended at the state or city level.
Gable end walls will be sheathed per Y101.4 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.

Y101.8 Exterior Wall Bracing

AMENDMENT
This section has been amended at the state or city level.
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 Y101.4. Any form of intermittent bracing is not allowed on an exterior wall. Intermittent bracing may only be used for interior braced wall lines.

Y101.9 Multi Story Construction

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This section has been amended at the state or city level.
Nail upper and lower story wall sheathing to common rim board in order to maintain continuity between stories.

Y101.10 Wood Floor Above Crawl Space Construction

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This section has been amended at the state or city level.
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.

Y101.11 Garage Doors

AMENDMENT
This section has been amended at the state or city level.
Garage doors are to be wind rated to 135 mph.
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