Drill Guide for Studs

Drilling Studs

• The most common type of stud is the 2-by-4, which actually measures roughly 1-1/2-inches by 3-1/2-inches. However, carpenters use wider lumber as studs, such as 2-by-6 (actually 1-1/2-inch by 5-1/2-inch), to complete advanced framing projects. Regardless of a stud's dimensions, you can determine appropriate hole size and location with a set of simple proportions. In load-bearing wall studs, you can safely drill holes that have a diameter equal to 40 percent or less of the stud's width. For example, the allowed maximum hole size in 2-by-4 bearing wall is roughly 1-7/16-inches in diameter. Additionally, the hole's edges must sit at least 5/8 inch from both sides of the stud. In partition wall studs -- studs that do not bear a structural load -- the allowable percentage increases to 60 percent. These proportions apply to studs of all sizes.

Notching Studs

• The term "notch" refers to cuts that run from one edge of stud toward the opposite edge. As with holes, you can determine allowable notch sizes using a set of proportions. In load-bearing walls, a notch may extend into a stud a depth equal to 25 percent of the stud's overall width. For example, the allowable notch size in 2-by-4 bearing wall is 7/8 inch. In partition walls, a notch may extend into a stud a depth equal to 40 percent of the stud's overall width.

Holes for Wiring and Plumbing

• Special requirements apply to wiring and plumbing holes. To protect electrical wires and pipes from nail and screw punctures, builders must place wiring and piping holes 1-1/4-inch from a stud's edge. This distance places wires and pipes beyond the reach of standard drywall screws, which drywall installers drive throughout stud edges. However, if builders must place a wiring or piping hole closer than 1-1/4-inch from a stud's edge, build codes require installation of a protective metal plate over the edge of the drilled cross section. Typically 1/16 inch thick, these protective plates are usually available in the electrical or hardware sections of home improvement stores.

Stud Drilling Tools

• Clean, properly aligned holes are a necessity if you plan to route rigid pipes or pull wires through studs. Although standard paddle bits and twist bits are suitable for drilling studs, specialized auger and boring bits help workers create perfectly straight, clean-edged holes. The deep, spiraling edges of auger bits resemble a corkscrew and the flat, opposing edges of boring bits resemble wings. These designs encourage stability during drilling and gently force the bit forward as it cuts. Although more costly than standard wood bits, auger and boring bits reduce the time and effort required to route pipes and wires.