Do You Need To Double Floor Joists Under Walls

Joists are spaced at regular intervals much like the studs in a wall frame.

Do you need to double floor joists under walls.

A cast iron tub with water and occupant can weigh in at more than 800 lbs. Set a hydraulic jack and post under the beam and jack up the joists about 1 8 in. Additional support for the floor joists is achieved by nailing the ends of the joists into headers. They are covered with subflooring panels of plywood or oriented strandboard osb to complete the floor s structural assembly and create the solid continuous platform on which you install tile carpet or other finish flooring.

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. This allows you to install a supporting post off the double floor joist to hold a second storey or a. 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. But larger is not always better when builders are constructing a home or adding a room addition.

Tack a beam under the sagging joists. The place where you ll be most tempted to create oversize holes and notches under the bathtub is the part of a floor you can least afford to weaken. The main reason for doubling up floor joists is to double the strength of a single floor joist. Why would you use a double floor joist.

In residential construction the floor sheathing is generally sufficient to support the vertical load from a non bearing partition wall that is parallel to the floor joists. Nailing two 2x4s together will work to span about three joists unless the sag is under a weight bearing wall. Jacking them up too fast may cause cracks in the walls and floors overhead. When i draw plans i locate joists under bearing walls only for parallel walls off layout but i do it with two joists spaced apart the depth of wallplates above.

Double floor joists are two joists side by side that are usually nailed or screwed together along the length. If you need to cut through a joist firm up the floor as shown in fig. 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.