PILING
INFORMATION
New Builds
As the availability of sites
has become more limited
and the cost of piled
foundations has decreased,
it is now commonplace to
utilise piled foundations for
buildings in ground
unsuitable for traditional
foundations.
In making the decision whether to pile or trench
fill, it is good practice to investigate the ground
conditions by performing test holes by using an
excavator (either on rubber tyres or tracks).
Rubber tyre excavators can usually dig to 13 ft and
tracked machines up to 20 ft. If either of these
machines is at full depth and the strata has not
improved then piling is almost certainly necessary.
In these circumstances, early consultation with a
civil or structural engineer experienced in soil
mechanics is recommended.
Apart from the danger of deep dig, (health and
safety regulations require excavations deeper than
1.2 metres to be propped), the breakeven point
between piles and trench fill will depend on many
other factors.
•
Over-dig due to collapsing sides can result in a
trench 3 to 4 times as wide as the bucket and
a concrete cost to match
•
The cost of spoil disposal and potential landfill
tax
•
The cost of shoring or risk of trench collapse,
(particularly near other properties where
piling is much safer than excavation below
adjacent foundations)
•
Ground water levels may make excavation
even at shallow depths impossible*.
(*Lowering the water table by pumping
groundwater can cause serious damage to
adjacent buildings. It is not uncommon to
drive piles as short as 2 metres rather than
dewater and risk damage to adjacent
property.)
Typically, we have found that clients find piles to be
more economical than 2 to 3 metres of under-
building.
© Precast Foundations (Piling) 2018
PRECAST
FOUNDATIONS
(PILING)