‘Thickening’ of Preliminary Items

It is generally accepted that where a contractor is entitled to an extension of time, he is also entitled to claim for time-related costs for the period of delay. Time-related include costs for providing site management, site establishment, plant and equipment, insurances, additional financing costs head office costs and the like, which are usually priced in the preliminaries section of the bill of quantities.

Are there, however, situations that a contractor may legitimately claim for additional resources, as opposed to the existing resources being deployed for an extended period? Well yes there are and this is known as ‘thickening’.

Consider a situation where the employer has instructed the contractor to carry out a substantial amount of additional work, but needs to meet a completion date earlier than the extension of time to which the contractor would otherwise be entitled. In such a case, it would be necessary to deploy additional labour, plant and machinery to carry out the work, for which he would receive payment under the contract rates and prices when evaluating the additional work. If he deploys additional resources however, he may also need to mobilise additional site supervision, management, administration staff and the like. Mobilisation and demobilisation of both productive and non-productive resources will probably cause the contractor to incur costs. The staff may also require additional site facilities in order for them to carry out their duties, but such costs would not be recovered through the rates and prices. This is thickening and is claimable by the contractor.

If it were not for the requirement to accelerate to meet the employers desired completion date, the contractor would be entitled to an extension of time, for which the employer would incur prolongation costs. The savings for prolongation would therefore possibly offset or contribute towards the thickening costs.


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