How To Join Two Floor Joists

Make sure your joist is straight because once you splice it this way it cannot be repositioned.

How to join two floor joists.

Place two hydraulic floor jacks under the 4 inch by 4 inch post and raise the post until it contacts the floor joists. If there was water damage make sure that whatever leaky pipe or condensation issue caused the rot is fixed. 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. Raise the jacks about 1 8 inch more.

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. Sistering or joining joists the term sistering joists is the practice of overlapping two joists by a certain distance across a beam to create an extended joist. The new sister joist is cut to the same length or slightly shorter as the old joist and is inserted into the joist cavity and snugged up against the old joist. But larger is not always better when builders are constructing a home or adding a room addition.

If the floor is sagging the damaged joist and or a few neighboring joists may need to be jacked up slightly to straighten or raise the floor so the sister joist can be put into place. 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. Only raise the jacks about 1 8 inch per. These problems must be addressed firsthand prior to implementing any restoration steps.