Jackson taught me

Lapping length is 40dia

said rebar is 16mm

Lapping length 16 x 40 = 640

this is the length to overlap a cut rebar on structural wall.

In this case, the contractor accidentally hacked the load bearing shear wall, not only that and he also cut off one of the rebar. We need to replace the rebar, by overlapping (not weld, as welding will weaken the bar strength) a new rebar.

The bigger the rebar, the more depth need to plant.