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How to Splice a Ceiling Joist

Ceiling joists may need splicing if they have been cracked during transport or construction. They might also be spliced if a piece has been cut out of one during prior renovations or if a very long joist is needed and you need to build it out of more than one piece of wood.

Broken or extra-long joists need reinforcing.

Ceiling joists may need splicing if they have been cracked during transport or construction. They might also be spliced if a piece has been cut out of one during prior renovations or if a very long joist is needed and you need to build it out of more than one piece of wood. When properly constructed, a joist splice can be virtually as strong as a solid piece of wood.

  1. Spread construction adhesive onto one face of each of the two 2-by-4s.

  2. Place one of the 2-by-4s on the side of the joist that is being spliced. Center the 2-by-4 over the crack or break in the joist. Tack the 2-by-4 down by putting a 4-inch-long screw into each end. Drive the screws in far enough to hold the 2-by-4 to the joist, but not so far in that they go through the other side of the joist.

  3. Put the second 2-by-4 on the other side of the joist so the joist is sandwiched between the two 2-by-4s. Screw this 2-by-4 to the joist with 4-inch-long screws, driving the screws all the way in so that they go through the 2-by-4, through the joist and into the opposite 2-by-4.

  4. Go back to the first two screws you drove in and finish driving them in so they go through the joist and into the second 2-by-4.

  5. Add more screws along the length of both 2-by-4s. The more screws you put in, the stronger the splice will be.

About the Author

Jagg Xaxx has been writing since 1983. His primary areas of writing include surrealism, Buddhist iconography and environmental issues. Xaxx worked as a cabinetmaker for 12 years, as well as building and renovating several houses. Xaxx holds a Doctor of Philosophy in art history from the University of Manchester in the U.K.