Differing site conditions

Definition

The clause that pays a contractor when the ground is not what the bid assumed.

Why It Matters

Anyone who digs prices the ground from borings and drawings, and the clause decides who pays when the ground disagrees. The federal version covers two cases: conditions that differ materially from what the contract indicated, and unknown conditions of an unusual nature for that kind of work. Either way the contractor must give written notice promptly and before the conditions are disturbed, and a request made without that notice, or after final payment, is not allowed. Where the clause applies and notice was given, the contract price and time are adjusted. A private contract can leave it out and put the whole risk on the contractor. For a buyer, read which contracts in the backlog carry it, and ask how the seller's crews are trained to stop and write before they dig on.

In numbers: An excavator who bid $400,000 and hits rock the borings never showed can recover the added cost under the clause, but only with written notice given before the rock is disturbed.