When constructing a conrete slab for the base for paving should you be investigating the subgrade to determine if piering is required or does this type of slab not have to worry about piering because it is only being used for paving not intended for vehicular traffic?
Similarly, can you assume that, if you have a 4m boulder retaining wall to the rear of a property which drops off further below to a creek, the land being retained is fill or could it be retaining natural ground?
