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.

Floor joists guidlelines. The notching and boring rules of thumb for solid lumber are shown in fig. Sometimes joists are notched at the end where they bear on a wall or sill. If your home is more than 20 years old your floor joists are most likely solid wood 2x8s 2x10s or 2x12s. Trus joist tji joist specifier s guide tj 4000 july 2019.

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. These joists may need reinforcin g to reduce bounciness sagging or excessive deflection in the floor or ceiling. Follow the rules to keep your floor solid you can notch and bore joists without sacrificing critical strength but you must follow the rules.

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. 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. You can notch and bore joists without sacrificing critical strength but you must follow the rules. 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.

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. Fire safe construction 3 floor performance and tj pro rating 4 5 section 1.