Floor Joist Notching

When necessary the holes should be located in areas with the least stress concentration generally along the neutral axis.

Floor joist notching. The notching and boring rules of thumb for solid lumber are shown in fig. Notching floor joists that is essentially notching the 2x10s and sistering 8s to each of the 3. Notching should be avoided when possible and holes bored in beams and joists create the same problems as notches.

If your home is more than 20 years old your floor joists are most likely solid wood 2x8s 2x10s or 2x12s. In situations when sistering damaged floor joists with lumber of similar dimensions it can be easy to notch and slide the sister board into place. Where larger notches and holes in joists should be and how they should be made.

Sometimes joists are notched at the end where they bear on a wall or sill. Holes must be at least 2 in. Floor joists constructed from large dimension lumber bear the weight of the structure above so notching them isn t recommended.

But this could weaken the floor to such an extent that it becomes structurally unsound. Notches should be no deeper than 0 125 times the depth of the joist. From the top and bottom edges of a joist.

When installing pipework or cabling floor or ceiling joists may need to be notched or drilled. Please follow these rules when notching joists. Notches in floor joists may occur in the top or bottom of the member but may not be located in the middle third of the span.

This also applies to wall studs for concealed showers etc notches should only be made in the top edge of the joist. Notching wood and boring rules engineered i beam rules. A notch may not exceed one sixth of the depth of the joist except at the very end where it may be one fourth of the joist depth.