The Hidden Costs of Piling

A constant frustration with purchasers of piling solutions is the difficulty in comparing prices of different options.

As there is no standardised Bill of Quantities for each piling solution, it is often difficult to compare one CFA piling quote with another. However, the real difficulty arises when comparisons are being made with alternative systems, such a Precast Concrete Driven Piling and CFA Bored Piling. Regrettably, this is often complicated by piling contractors omitting some cost headings, such as clearing spoil away from rigs and the cost of removing excessive materials/spoil arisings from site. Furthermore, the level of Main Contractor attendances required can vary drastically – a cost that is often not known until work commences on site.

For example, the cost of providing an excavator in full time attendance to a CFA piling rig to remove spoil arisings from the area of the piling during boring is rarely detailed in piling quotations. Further costs associated with boring out piles is the cost of removing and storing spoil to a tip on site for drying out prior to loading and removingthe spoil from site. In most cases, the Main Contractor must allow additional sums in their cost estimated for this work. Typical cost per metre of pile for this work, based on a 450mm dia pile is €5/m or circa 15% of the quoted pile cost! If the project happens to be in a ‘brownfield’ site, the cost of disposing of spoil from site can be very expensive indeed (we are aware of costs exceeding €500 per m3!)

Precast Concrete Driven piles can also present difficulties in relation to unspecified costs. The most common is the cost of excessive pile lengths over ground. In most cases the costs of these piles is transferred to the Main Contractor at the full BoQ rate – even if the pile lengths are +3m above pile cut-off / working platform level. As you might imagine, this is a cause of contention! A further cost associated with this issue is the subsequent cost of removing these excessive and wasteful lengths of pile from site – often landfill site do not want to accept them.

As with all of these types of issues, the devil is in the detail, and the specifics of who is responsible for what must be agreed prior to engagement. The simplest solution is to make the piling contractor responsible for all the waste and spoil generated on site – then a direct comparrison can be readily made.

How long does it take to complete the piling process?

Depending on the type and extent of the project, the time frame of the piling stage can vary sensibly.

Piling can be completed within days for small projects, such as single houses or medium-sized developments, or within months for more substantial projects, such as large retail developments.

Usually, the duration of the piling stage includes one day for mobilisation and demobilisation, the main working period and the testing element.

Replacement piling is usually based on longer completion time, as in this case, wet concrete is used. This necessarily implies a delay in the follow-up of work and in the testing stage (as concrete has to set).

On the contrary, displacement piling, and more specifically Precast Concrete Driven Piling, allows for speed and quality of work. Non weather-dependant, precast piles can be positioned, driven, tested and cut, with minimal delay between each stage of the works.

A schedule of work is usually drawn up before the start of piling, and a programme is agreed.

I have a building project; do I necessarily need piling?

Piling is only required when the ground conditions are poor or not sufficient. Prior to starting building, it is recommended that a site investigation is carried out, in order to ensure that the ground will support the load of the new building.

(To read more about the site investigation, refer to our data sheet F006 “Understanding your Site”.)

Upon completion of this investigation, the project engineer will decide what type of foundations shall be required. This can be standard foundations (concrete raft, trench…) or piling.


Generally, once the digging for standard foundations goes beyond a depth of about 2 metres, piling methods would become a preferred option.