Notching Roof Joists

Top edge 0 1 0 2 x span.

Notching roof joists.

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. This also applies to wall studs for concealed showers etc. 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. Cutting notches and drilling holes in 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.

Birdsmouth joint how to cut a birdsmouth and how to cut and install roofing rafters and joists. Notches should be no deeper than 0 125 times the depth of the joist. Notching joists up to 250mm depth. 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.

0 15 x depth of joist. Centre line 0 25 0 4 x span. Notches can only be made in the top or bottom of the joists not both within the permitted area to a maximum of 35mm. 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.

It s important to calculate the siz. Additional holes must be at least three diameters centre to centre apart. Please follow these rules when notching joists. Limit the length of notches to one third of the joist depth.

Rules for notches in joists. These joists may need reinforcin g to reduce bounciness sagging or excessive deflection in the floor or ceiling. Notches should only be made in the top edge of the joist. Sometimes joists are notched at the end where they bear on a wall or sill.

Roger goes over the best practices and rules for notching and drilling holes in joists while filming our bathroom series. No notching in the middle third of a joist. Maximum notch depth in the outer third of a joist is one sixth of the joist depth. Drilling joists up to 250mm depth.