Sistering involves bolting, nailing, or screwing a new piece of lumber directly against an existing joist, stud, or rafter. This technique restores strength to timber that has rotted, cracked, or sagged, or upgrades the load-bearing capacity of a floor or roof without removing the original framing. The new piece must overlap the damaged section significantly and bear on solid supports to be effective.
Heard on the job
We need to sister those floor joists before we put the heavy cast iron tub in the bathroom.
Insider tip
Always apply a heavy bead of construction adhesive between the old and new boards before bolting them together to prevent floor squeaks.
Also heard as
- sistering