Drilling Holes In Floor Joists For Plumbing

Holes bored in joists shall not be within 2 inches 51 mm of the top or bottom of the joist and the diameter of any such hole shall not exceed one third the depth of the joist.

Drilling holes in floor joists for plumbing. This is where the compressive and tensile load distribution is neutralised holes should have a diameter of no greater than 0 25 times the depth of the joist holes should be no closer together than 3 times the largest diameter permitted. Notches in the top or bottom of joists shall not exceed one sixth the depth and shall not be located in the middle third of the span. That gives you a 5 1 4 in. Keep the hole at least 2 in.

For a 2 10 where actual depth is 9 25 inches the maximum allowable hole diameter would be just over three inches. If the joist is 12 inches deep you need a hole saw that is 4 inches in diameter or smaller. Diameter plenty big enough for running cable. These joists may need reinforcin g to reduce bounciness sagging or excessive deflection in the floor or ceiling.

The hole cannot be larger than one third the depth of the joist so the maximum hole size for a 2 12 joist actual size 1 1 2 x 11 1 4 in is 3 3 4 in. Tradespeople often need to cut notches or holes in floor and ceiling joists to run pipes ductwork or wires. Select a hole saw that is the same size or smaller than one third the joist depth measurement. From the top and the bottom if it s a dimensional lumber joist.

Where and how to drill joists for electrical cables or plumbing runs depends on what type of floor framing you have. Holes cannot be closer than 2 to the bottom or top of a joist or to another hole or notch in the joist drilling floor joists. Area in the middle of the 2 10 joist where the hole can go. If there are other holes or notches keep at least 2 in.

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. The diameter of holes shall not be greater than 1 3 the depth of the floor joists. Although notches aren t allowed in the center third of a joist s length you can drill holes anywhere along the length of the floor joist in that 5 1 4 in. Holes should only be drilled on the centre line of the joist.