Typical wall crack.
Pured concrete shrinks. This house is no different than others. When the concrete shrinks, it cracks at the point with most stress.
Floor opened and sealant applied
The first two steps is to open the floor around the crack and apply a sealant directly into the crack.
Drainage foam
A 4" drainage foam is applied over top of the sealant in case the first step leaks.
Fleant sealant troweled over top
A flexible sealant is applied over the foam and then smoothly troweled over (not shown)
Waterproof membrane
A waterproof membrane is attached and se4aled to wall to insure that no moisture gets through. All these layers are tuck under the floor.
Re-concrete the floor
The last step is to re-concrete the floor up to the membranes with a flash of Delta MS to make sure any moisture gets tot he gravel bed below.