Where the underlying ground consists of permeable materials, such as sand or sandy clay, the cost of the technique will be significantly increased due to the requirement of cut-off walls into non-permeable layers to seal off the vacuum. It has been suggested by Carter et al.
Where the foundation comprises permeable materials such as sand or sandy clay, the expense of the process rises substantially because cut-off walls must be built into impermeable layers to seal off the vacuum. It has been proposed by Carter et al.