By jacking up the ceiling of the basement you.
Jacking up a floor joist.
Raise each jack by 1 8 inch at a time this will help to reduce any damage to window frames and plaster or drywall walls above the floor.
If a crack or sag is isolated to one area the sister joist should extend at least 3 ft.
Place support of the floor joists with wood studs.
A day until they re level.
Make repairs to settling piers and weak joists to fix swagging floors and roof lines.
After the old joist is lifted by the jacks the new joist will now sit on the supporting walls or wall and i beam in our case while the old is lifted off of the structure.
The idea behind sistering joists is that you jack up the sagging original joists add the new ones next to the old and join them together.
The only tools required is a bottle jack string straight claw hammer circular saw and a light source.
On both sides of the problem area.
Jacking them up too fast may cause cracks in the walls and floors overhead.
Figure 3 jacking up floor joists.
The 4 inch lally posts can be replaced by 6 x 6 inch lumber.