What size of predrilled hole is needed for the lag screw?

To determine the appropriate size of a predrilled hole for a lag screw, it is essential to consider the relationship between the screw's diameter and the hole diameter. A predrilled hole that is 1/16" greater than the diameter of the bolt allows for adequate clearance. This slight increase in size is necessary because it enables the lag screw to enter the material without excessive resistance, which could lead to splitting or damage, particularly in wood.

This size also strikes a balance that maintains a secure fit while allowing for some degree of expansion and contraction of the material being fastened. Using a hole that is too large can compromise the holding strength of the lag screw, while a hole that is too small may prevent proper seating and increase the risk of damaging the screw or the material. Thus, drilling a hole that is 1/16" greater than the bolt's diameter is the recommended practice to ensure effective and reliable installation of lag screws.