Sistered Joist

A new joist bolted or nailed alongside an existing joist to reinforce it. Used to repair damaged joists, increase floor stiffness, or add capacity for heavier loads.

In Detail

Sistering doubles the bending capacity at the sistered location. The new joist must extend at least 3 feet past each side of the damaged area and be fastened with structural screws or through-bolts per engineering requirements. Construction adhesive between the joists significantly increases composite action. For full-length sistering, the new joist should bear on the same supports.

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