Timber piles with concrete beams
As with all the previous pier and beam systems, a qualified engineer must design these footings.
Power driven timber piles are slightly different to the previous pier and beam systems - a building inspector cannot inspect the foundation. This is because there is no excavation with power driven timber piles.
The vibration transferred to the ground by the pile driving rig may also shake and move buildings in the immediate vicinity. The building surveyor, design engineer, checking engineer and supervising site engineer must gauge and assess the amount of vibration before and during construction.
Where piling of any kind is required, the sub-surface soil in the vicinity is likely to be poor. So, the existing buildings may not be founded on piles and may be perched on the soft/fill soil with minimum support. Pile driving vibration could easily disturb these buildings, resulting in cracking or failure and collapse.
The last 10 blows on the piles are recorded. This, in effect, is a measure of the resistance of the soil and determines when a pile is 'set'.
