Doing so strengthens weak joists and can help straighten sagging joists.
Sistered sistering floor joists.
So a 2 foot extension will be 4 feet sistered to the existing joist with appropriate fasteners 3 nails in a w pattern every 12.
Sistering joists for a cantilever requires removing the rim joist and sliding the new joist in beside the existing one.
If you have sagging cracked or twisted joists which can happen in older houses this project will provide the extra support the floor needs.
This article provides step by step instructions and pictures on how to make structural repairs by sistering floor joists alongside weak joists.
Framing lumber is the typical.
Sistering joists means beefing them up with additional material.
The section being inserted and sistered should be twice as long as the cantilever.