Precast ground beams
Traditionally ground beams for low-rise housing and similar applications are constructed in situ. This is time consuming, as it requires some type of formwork unless the ground is firm enough for stable trenches to be dug and filled with concrete. The approach is particularly difficult when ground conditions are poor, necessitating piled foundations. (This will become more common with the increased use of ‘brownfield’ sites.) The alternative is to use precast ground beams. These are cast to the appropriate length in the factory and are simply placed spanning between the tops of the piles. They are then connected to each other, and to the piles, with a small in situ concrete ‘stitches’. Some precast ground beam systems incorporate connections to secondary beams, which can be used to form a beam and block ground floor for the building.