You should not start a grillage below that mark, when exposing which there may be a bulging of the soil from under the foundation.
Note. If necessary, in the device of a grillage or rand beam in the plane of the base itself before the start of the production of these works, transverse (forces) beams resting on sleepership cells are being launched through special nests in the wall to perceive part of the load from the structure.
