Should You Drill Floor Joists

As part of any new installation work or a re wire a cable trunking or cable tray sometimes has to pass through an element of building construction such as a floor wall or beam necessitating the formation of a notch or opening in the element.

Should you drill floor joists. No greater diameter than 0 25 times the depth of. For this discussion we will focus on the traditional dimensional floor joists. How to position holes correctly so they don t weaken the joist. Guide to making safe cuts holes and notches in floor joists and ceiling joists.

You can t notch or drill them anywhere. First let s take a look at the code 2012 international residential code to see what is required when drilling floor joists. Measure down 2 inches from the top edge of the joist. When you walk around in your home you probably don t think much about what you re standing on and you might just be surprised by how many layers sit below you every day.

B the guidelines are simple. For those working with the less common open web or floor truss joists fig. The guidelines for these are shown in fig. Mark the joist at that spot with a pencil.

This sample table gives minimum floor joist sizes for joists spaced at 16 inches and 24 inches on center o c for 2 grade lumber with 10 pounds per square foot of dead load and 40 pounds of live load which is typical of normal residential construction. Rules for holes in joists. Irc r502 8 and irc r802 7. You can safely drill joists for electrical and plumbing runs without weakening the joists if you follow the rules.

Measure up 2 inches from the bottom edge of the joist and mark it again. Cutting notches and drilling holes in joists. The rules for positioning notches in floor joists image courtesy of niceic to understand the forces at work in a joist particularly the tension and compression forces please see our project that explains how the forces that affect buildings work.