What Is a Differing Site Conditions Clause?
The differing site conditions (DSC) clause is the construction contract's ground-risk allocation — entitling the contractor to relief when the subsurface differs materially from the contract's indication (Type I: the indicated conditions) or from the normally expected (Type II: the unusual). The clause's purpose: the contractor need not inflate the bid for the unknowable ground; the owner retains the ground risk the investigation didn't resolve. The Federal Acquisition Regulation's clause is the model; the private contracts adapt it.
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Type I vs. Type II
Type I (the indicated — the conditions differing materially from the contract's borings, the GBR, the drawings; the contractor's reliance — the indication), Type II (the unknown — the conditions differing materially from the normally expected for the locale; the unusual — the buried obstruction, the artesian condition). The notice (the prompt written — the condition's documentation before the disturbance; the notice's timeliness — the claim's prerequisite).
What the clause does
The risk allocation (the owner — the ground's residual risk; the contractor — the indicated conditions' performance), the bid (the contractors pricing the indicated — the contingency for the unknown reduced; the bid's competitiveness), and the adjustment (the equitable — the time and the cost; the documentation — the daily records).
Drafting and disputes
The GBR's role (the baseline — the Type I measured against; the careful baseline drafting), the exculpatory (the disclaimers purporting to shift the risk — the courts' skepticism; the DSC's survival), and the resolution (the DAB/DRB — the real-time; the documentation — the contemporaneous records winning). The DSC clause is the underground project's fairness — the ground's surprises shared, not gambled.
The bottom line
The DSC clause (FAR model) grants relief for Type I (differing from indicated/GBR) and Type II (unusually unexpected) subsurface conditions — requiring prompt notice and documentation.
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