Q: Can screws be used instead of nails for attaching wall sheathing to framing?

A: Roe Osborn, a senior editor at JLC, responds: There is a common misconception in the building industry that screws always outperform nails when attaching wood to wood. It’s true that screws have a highly effective withdrawal resistance, which makes them excellent fasteners for tasks such as avoiding squeaks in flooring assemblies, resisting uplift forces that occur in roofs, and holding deck ledgers tight to a building. However, there are certain applications such as sheathing where nails are superior for fastening. I recently spoke with Nick Robertson, a product application specialist for Huber Engineered Woods about this topic.

Robertson first pointed out that by design, nails are less brittle than screws, which leads to an increase in shear strength for nails. In other words, if two pieces of wood (or wood and metal) are fastened together and those materials are forced in opposite directions, the forces acting on the fastener are likely to cause the shank of a screw to break. A nail subject to the same forces is much more likely to bend without breaking, which in turn keeps the two pieces of wood joined together.

To help illustrate the point, Robertson took this simple concept and applied it to a braced wall application. Braced walls are areas of framed wall that contain no door or window openings (although some engineered braced-wall designs do allow for openings). These walls must have let-in bracing, diagonal board sheathing, or some sort of code-approved sheet material to stiffen the structure against racking. In a typical braced wall, the framing is primarily secured by a structural sheathing panel, such as OSB or plywood. The most important force at play for this wall is a shear force from the wall moving back and forth laterally due to wind or seismic activity.

The sheathing panels brace the framing to stop the wall from toppling over, and increasing the number of fasteners increases the wall’s shear resistance. Now imagine if some of those edge fasteners start to fail. For every fastener that fails, the shear resistance of the entire wall decreases; in the worst-case scenario, the entire wall might end up failing, which could ultimately cause the failure of the entire structure.

Because of this concept, many building-standards groups specify that only nails and staples are to be used for wood structural panel attachments in wall applications: ANSI National Design Specification, NDS Chapter 12: Dowel-Type Fasteners; AWC Special Design Provisions for Wind and Seismic, Chapter 4: Lateral Force-Resisting Systems; and the 2018 International Building Code, Section 2304.10: Connectors and fasteners.