Cutting Holes In Floor Joists

Where and how to drill joists for electrical cables or.

Cutting holes in floor joists.

A hole saw is a short tube shaped cutting tool with drill bit through the center of the cylinder and a. 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. Often hole size can be increased and holes can be placed closer to bearing than shown on the chart based on actual design spans and loads. For a 2 10 where actual depth is 9 25 inches the maximum allowable hole diameter would be just over three inches.

In order to maintain the support integrity of the ceiling or floor joist or rafter system it is important that if joists are cut that the load that was bearing on those joists be transferred to a modified support system. Rules for holes in joists. Cutting notches and drilling holes in joists. Sometimes joists are notched at the end where they bear on a wall or sill.

Holes cannot be closer than 2 to. Refer to the hole chart on page 9 of the tji specifiers guide for uniformly loaded joists. Permitted if the group perimeter meets. Please follow these rules for making holes in joists.

If the joist is 12 inches deep you need a hole saw that is 4 inches in diameter or smaller. Tradespeople often need to cut notches or holes in floor and ceiling joists to run pipes ductwork or wires. 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. They are located 3 away horizontally edge to edge from a larger hole.

Drill holes with a diameter of no more than one third the depth of the joist staying 2 in. Holes anywhere in the web area of engineered i joists except within 6 in. Minimum applies to all holes except knockouts closely grouped round holes are. Trus joist tji joists.

If you have manufactured floor joists you will want to consult the particular manufacturer s literature. Of walls and rim joists. The diameter of holes shall not be greater than 1 3 the depth of the floor joists. If the cut outs are too large or in the wrong location the joist can be weakened and unable to support the load it was designed for.