The cost of disposing of excavated materials means many architects and contractors are considering piled foundations as a cost effective option for low rise housing on brownfield sites. Piled foundations typically use less material to construct than conventional trench fill but the criteria for their use remains uncertain. With this in mind, the NHBC Foundation recently published Efficient design of piled foundations for low-rise housing: Design guide, the aim of which was to explore the design approach and selection of a piled foundation approach for low rise housing.
The report finds that, contrary to some previous perceptions, there should be no separate design criteria when considering piled foundations for low rise housing. The governing factor that dictates foundation design is the potential damage which could occur to the built structure. Cracks and fissures are, quite simply, unacceptable and alleviating the possibility of differential movement, which ultimately leads to cracks, is the key to combating this problem.
Designed in an efficient way, piled foundations create an accurate and sustainable substructure that prevents differential movement. They hold many additional benefits for builders, requiring less material to construct and avoiding extensive excavation of ground material, meaning they can be constructed cost effectively and at speed.
In addition, when considering the vital question of sustainability, the report shows that the construction of piled foundations results in far less embodied carbon than alternative options. They can also go some way to ensuring new homes meet higher levels of the Code for Sustainable Homes.
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