How To Join Two Floor Joists

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.

How to join two floor joists.

These problems must be addressed firsthand prior to implementing any restoration steps. Avoid making the joint in the center 1 3 of the span. This is unusual in new deck construction and would only be necessary for very long spans that exceed the length of your longest boards. 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.

Place two hydraulic floor jacks under the 4 inch by 4 inch post and raise the post until it contacts the floor joists. 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. Only raise the jacks about 1 8 inch per. But larger is not always better when builders are constructing a home or adding a room addition.

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. The answer is yes in most cases if you use real plywood to splice the two pieces on both sides and nail appropriately. 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. Make sure your joist is straight because once you splice it this way it cannot be repositioned.