Notching A Floor Joist

No notches in the middle 1 3 of the joist but holes are permitted here.

Notching a floor joist. Rules for notches in joists. No notches deeper than 1 6 the joist depth. Notching involves the removal of material at the top and bottom of the joist where compression and tension forces are working to resist bending that is deflection.

Notches should be no deeper than 0 125 times the depth of the joist. No end notches where the joist is supported greater than 1 4 the joist depth. Notching floor joists another valid point.

Where larger notches and holes in joists should be and how they should be made. In some cases a plumber or another mechanical contractor might. The length of a notch should not exceed 1 3 the joist depth.

The maximum depth of a notch at the end of a joist where it rests on a wall or beam can t exceed one quarter of the joist depth. A hole or notch that is too big or in the wrong place can seriously weaken the joist even to the point of failure. Over notching or not jacking enough generally newer home floor joists are made from 2x8s or new engineered i beams older homes however may have 2x6s instead.

While it is a good idea to replace rotted material with 2x8s it may require some notching to fit between the sub floor and ledger board. Holes may only be made on the joist s centreline within the permitted area to a maximum diameter of 65mm. No holes closer than 2 inches to any other hole or notch.

Additional holes must be at least three diameters centre to centre apart. However when a joist is notched or drilled the reduction of wood fibers reduces the ability of the member to withstand compressive and tensile forces. Limit the length of notches to one third of the joist depth.