There is a common myth that all tornadoes are so strong that structural failure is inevitable, no matter how well a building is constructed. But in fact, weaker tornadoes rated as EF-0, EF-1 or EF-2 by the National Weather Service comprise 95% of all tornadoes. A home that is carefully constructed, in accordance with current building codes, can withstand these smaller, less violent storms. Implementing these nine tips in the design and construction of residential structures can help prevent damages caused by high wind events. More on resilient construction.

1. Roof Sheathing Attachment
Nail roof sheathing with 8d ring-shank or screw-shank (0.131 in. x 2-1/2 in.) nails at 4 inches on center along the ends of the sheathing and at gable-end walls and 6 inches on center along intermediate framing.

2. Gable-End Bracing
One of the weakest links in residential structures during high wind events is the connection between the gable end and the wall below. Tie gable-end walls back to the structure.

3. Gable-End Wall Sheathing
Gable-end wall failures are frequently observed in tornado events when non-structural sheathing is used. Sheath gable-end walls with wood structural panels, such as plywood or oriented strand board (OSB).

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4. Roof-To-Wall Connection
Under high wind loads, the roof-to-wall connection is subject to both uplift and shear due to positive or negative wind pressure on the walls below. For the roof-framing-to-wall connection, use a hurricane/seismic framing anchor or equivalent connector attached on the exterior (sheathing side) of the exterior walls. A cost-effective solution for meeting IRC lateral and wind uplift load requirements.

5. Connection Between Stories
The most effective way to provide lateral and uplift load continuity is to attach adjacent wall sheathing panels to common framing. Nail upper-story sheathing and lower-story sheathing into common wood structural panel Rim Board.

6. Wood Structural Panel Wall Sheathing Attachment
Nail wall sheathing with 8d common (0.131 in. x 2-1/2 in.) nails at 4 inches on center at end and edges of wood structural panels and 6 inches on center along intermediate framing. This enhanced nailing will improve the resistance of the wall sheathing panels to negative wind pressure. Staples offer less resistance to blow-off than nails and so a greater number of them are required to achieve the same level of resistance. Find additional solutions for code-compliant wall construction.

7. Continuous Wood Sheathing
Continuously sheathe all walls with wood structural panels including areas around openings for windows and doors. Nine more reasons to build with fully sheathed wood walls.

8. Wall Sheathing to Sill Plate
Extend wood structural panel sheathing to lap the sill plate. The connection of the wall sheathing panel to the sill plate is important because this is where uplift forces are transferred into the sill plate and into the foundation through the anchor bolts.

9. Anchor Bolts
Space ½-inch anchor bolts 32 inches to 48 inches on center with 0.229-in. x 3-in. x 3-in. square plate washers.

Full design and construction details, including illustrated examples, can be found in APA’s Building for High-Wind Resilience in Light-Frame Wood Construction design guide. Download this and other construction guides for free at www.apawood.org/resource-library.