Framing nails used in wood framed construction are available in many sizes with different names that refer to a specific diameter and length. In addition, many framing nails are designed to be used with nail guns for quick installation, while others are more commonly driven in place with a hammer. So which nail should you use when fastening a beam or joist hanger? Does it matter? The answer is yes!
Manufacturers of connection hardware, such as Simpson Strong-tie, always indicate what type of nails should be used with their products. They typcially specify 16d, 10d or 8d common nails for the installation of hangers, straps and ties. On occasion they will specify a 16d sinker nail or 10d x 1 1/2″ Teco nail. So why is this important? All of the hardware used in wood framed construction is tested and safe allowable loads are determined and published. Structural engineers and designers will then specify hardware for connections based on these allowable loads and expect the hardware to perform as advertised.
When we conduct framing observations at residential construction sites, we typically find beam, josit and truss hangers installed with 8d or 10d nail gun nails. These typical framing nails are usually .131″ Dia. x 3″ (8d framing nail) or .148″ Dia. x 1 1/2″ (10d Teco nail). Using these typical framing nails in the installation of most hangers can result in a reduction of over 30% in hardware capacity, (see Simpson’s “Nail Design Information“). In addition, many of the modern hangers use “Double Shear” or diagonal nails. It is very important that these nails have the proper length to adequately penetrate both members in the connection.
This creates a bit of a dilema for a designer. We are not always able to observe the installation of this hardware. Should we assume that the connection hardware will be installed with incorrect fasteners and reduce the allowable capacity of the hangers we specify? This results in larger, more expensive hangers with more fasteners. On the other hand, larger common nails seem to be less common by industry standards these days. They cost more and raise the price of construction.
Our approach has been a compromise. There are many instances where hangers have extra capacity and smaller nails can be used. We include “Lumber and Hardware Notes” or “Hanger Schedules” on our drawings, indicating the type of nails that should be used with the hangers we specify. We try and specify 16d sinker nails (.148″ Dia. x 3 1/4″), 8d framing nails (.131″ Dia. x 3″) and 10d Teco nails (.148″ Dia. x 1 1/2″)whenever possible.
What has been your approach both in the field and during design? Read other posts about residential construction in the Wood Framed Construction category of our blog.