Floor Joists Guidlelines

The notching and boring rules of thumb for solid lumber are shown in fig.

Floor joists guidlelines.

Common sense tells you that large floor joists can carry more load and spacing joists closer together also increases the load bearing capacity of a floor. You can notch and bore joists without sacrificing critical strength but you must follow the rules. Fire safe construction 3 floor performance and tj pro rating 4 5 section 1. If your home is more than 20 years old your floor joists are most likely solid wood 2x8s 2x10s or 2x12s.

That s the real reason you want to follow the notching and boring guidelines. 9 16 tji joists design properties 6 floor span and load tables 7 8 tips for preventing floor noise 8 allowable holes 9 cantilevers 10 11 roof span and load tables 12 13 framing. But larger is not always better when builders are constructing a home or adding a room addition. The extra two inches of vertical distance when a floor is framed with 2 x 10 joists rather than 2 x 12s can be quite important for example.

These joists may need reinforcin g to reduce bounciness sagging or excessive deflection in the floor or ceiling. Section r502 10 of the international residential code states that header joists can be the same size as the floor joists when the header joist span isn t greater than 4 feet but if the header joist span is more than 4 feet you ll need to double the header joist and ensure that it s capable of. Additional support for the floor joists is achieved by nailing the ends of the joists into headers. Follow the rules to keep your floor solid.

Sometimes joists are notched at the end where they bear on a wall or sill. Follow the rules to keep your floor solid you can notch and bore joists without sacrificing critical strength but you must follow the rules.