Lateral Bracing in Gable End Walls

Gable end walls are the triangular sections of wall that extend above the top plate at the gable ends of houses with gable roofs. Gable end walls that are inadequately braced or improperly anchored are vulnerable to collapse during high winds.

During a hurricane, tornado, or high winds, gable end walls can be damaged or detached from the rest of the structure, leading to severe damage to the roof and other structural members of the house (Figures 1 and 2). A compromised gable end wall can allow rainwater to enter the building causing severe damage, including saturation of insulation and ceiling drywall, potentially leading to collapsed ceilings and extensive damage to the interior of the home and its contents.

Wind forces both push (inward acting) and pull (outward acting) on houses, so it is critical to brace the gable ends to resist wind pressures in both directions. The potential critical failure points are the gable end wall connections at the roof framing and sheathing above and the wall below, gable wall framing members, and gable wall sheathing.  

The International Residential Code (IRC 2018) requires exterior building components and their attachments to be capable of resisting design wind pressures. For some high-wind regions, the IRC requires wind design in accordance with other methods including the International Building Code (IBC 2018).  

Homes located in coastal high-wind areas including Hurricane-Prone Regions generally require enhanced attachment that can withstand greater wind speeds than the rest of the country. The IRC defines Hurricane-Prone Regions as areas along the Atlantic and Gulf Coasts where wind velocity is >115 mph, and Hawaii, Puerto Rico, Guam, the Virgin Islands, and American Samoa (see the IRC wind map in the Climate tab). Confirm with the local building department if the house is in a hurricane-prone region and if local requirements exceed those of the IRC.

The IRC does not specify requirements for bracing gable end walls for wood framing but has minimum requirements for continuous roof sheathing at gable end walls, including fastener (nail) type, spacing, and penetration depth into structural members (see the Compliance tab for details). Section R603.3.1.1 of the 2018 IRC specifies gable end walls with heights greater than 10 feet (3,048 mm) are to be anchored to foundations or floors in accordance with IRC Table R603.3.1(1) or R602.3.3.1.1(2). IRC Section R603.3.2.1 specifies stud size and thickness for the gable end walls.

The Insurance Institute for Business and Home Safety® (IBHS) offers guidance, best practices, and voluntary construction standards and programs for building in disaster-prone areas including hurricane and high-wind zones. The IBHS FORTIFIED HOME™ standard is designed to make homes more resilient and durable; guidance is available for New Construction and Existing Homes in Hurricane zones and High-Wind zones  There are three levels of FORTIFIED Home: FORTIFIED Roof™ focuses on the roof; FORTIFIED Silver focuses on roof overhangs, opening protection, gable ends, and attached structures; FORTIFIED Gold focuses on tying all of the components of the structure together. 

The IBHS FORTIFIED Home Hurricane Standard requires gable walls subjected to high winds to have structural sheathing attached to the vertical face consisting of 7/16-in. OSB or plywood. The IBHS FORTIFIED Home High Wind Standard requires gable end walls to have a structural wall sheathing that is a minimum of 3/8-inch plywood or OSB or equivalent.

How to Install Lateral Bracing in Gable End Walls

1. Strengthen the gable end wall, as required:
   • Minimum 3/8-inch thick structural wall sheathing over the entire gable end wall
   • Maximum 24-inch spacing between studs on gable end walls.
2. Strengthen the gable end wall connection to the wall below using metal bracket connectors and one of the following methods:

• Attach the bottom chord of the gable end wall to the wall below using right angle gusset brackets consisting of 14-gauge or thicker material with a minimum load capacity of 350 pounds. Install the right-angle gusset brackets along the wall where the gable end wall height is greater than 3 feet at the spacing specified in the table below. Use a minimum of two fasteners specified by the manufacturer to attach the angle gusset bracket.
• For a conventionally framed gable end wall, attach each stud along the wall where the height of the wall is greater than 3 feet to the bottom plate using a stud-to-plate connector. Connect the bottom plate to the wall below using 4.5-inch, ¼-inch-diameter screws.

For steps 3 through 5, refer to Figure 3.

3. Install horizontal bracing, perpendicular to the gable wall, at the bottom chord or ceiling joist, and at the top chord or roof rafter, at each gable end wall stud greater than 3 feet high. Attach bracing using three #8 x 3-in. screws at each truss chord or rafter and joist.

4. Attach a vertical retrofit stud, between the upper and lower horizontal bracing, to each existing gable wall stud. 

• Attach a retrofit stud to the upper and lower horizontal bracing using metal straps, minimum 20-gauge x 1-1/4-in. wide with pre-punched fastener holes, using #8 screws.
• Attach retrofit stud to existing stud using #8 x 3-in. screws at 6 inches on-center
• The maximum allowable gap between the retrofit stud and bracing is 1/8-in. at the lower brace and 1/2-in. at the upper brace. 

5. Install compression blocks on horizontal bracing bearing tightly against the vertical retrofit stud, to restrain horizontal movement. Attach compression blocks using three #8 x 3-in. screws; screws must not go through the strapping.