Occasionally, investigations will conclude that part or all of the foundation is inadequate to support the weight of the building. This might be due to the foundation depth, width or the poor strength of the sub-soils. Underpinning extends the depth of the affected foundation down to a suitable level, to ensure future stability. Traditionally, this can be achieved by excavating below the foundation and placing new concrete below. Occasionally, the underpinning may need to go deeper, and a mini-pile solution may be adopted.