How To Overlap Floor Joists

This handout is intended to provide only general information for further information contact the building safety division.

How to overlap floor joists.

The long view makes the overlap seem longer but i believe the nearest one is less than a foot with very few nails. You should overhang at least a couple of feet on each side of the beam. Joist spacing common joist spacings for 2 by 10 joists and other dimensional lumber sizes are 12 16 and 24 inches. How does the overlapping joists work with the sub floor.

When the sagging joists are level apply a generous bead of construction adhesive to the existing joist. Floor joists lapping splicing 2013 california building code section 2308 8 table 2304 9 1 the following are general requirements for floor joist lapping and splicing based on the 2013 ca building code. Additional support for the floor joists is achieved by nailing the ends of the joists into headers. These problems must be addressed firsthand prior to implementing any restoration steps.

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. If the floor joists overlap then you will have the center of the 6th joist at 48 inches on one side of the floor and 46 1 2 or 49 1 2 on the other side of the floor. But it s usually best to run the sister joist over the entire span. In these cases the overlapped joists help tie the framing together by combining the rigid members over a beam.

If a crack or sag is isolated to one area the sister joist should extend at least 3 ft. Drooping and joist sag can be seen in the photo. Doing so strengthens weak joists and can help straighten sagging joists. Most often floor joists need to be sistered because of two problems either water damage which leads to rot or termite damage that crumbled the joist.

The longer the overlap distance the stronger the connection. Joists that are closer together can support. If there was water damage make sure that whatever leaky pipe or condensation issue caused the rot is fixed. Not sure if that makes sense or if i have this all wrong.

Framing lumber is the typical. On both sides of the problem area. Sistering joists is commonly used when adding onto an existing deck or repairing a deck. Floor joists support structural load and require lumber species capable of supporting those loads.

Sounds like butting them end to end would solve this issue. Two species used for structural lumber include douglas fir and southern yellow pine. Here is a pathetic attempt to splice some floor joists under the bathroom.