Contracts

What are differing site conditions in construction?

Differing site conditions are physical conditions found at the site, usually below ground or hidden, that differ materially from what the contract showed or from what a contractor would normally expect.

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A differing site condition (DSC) is the rock nobody drew, the groundwater the boring logs missed, or the buried foundation from a building torn down decades ago. When the contract has a differing site conditions clause, the contractor can get more time and money for the extra work, as long as it follows the notice rules. Without a clause, the contractor generally carries that risk, which is why the clause matters so much.

The federal version is the model most people know. FAR 52.236-2 recognizes two kinds of conditions, commonly called Type I and Type II. Many state, local, and private contracts use similar language, including the concealed conditions provision in common industry forms.

Type I and Type II conditions

The two categories in FAR 52.236-2
TypeWhat the clause saysExample
Type ISubsurface or latent physical conditions at the site that differ materially from those indicated in the contractBorings show clay to 20 feet; the excavator hits rock at 8 feet
Type IIUnknown physical conditions of an unusual nature that differ materially from those ordinarily encountered in the workAn abandoned, undocumented fuel tank inside a wall cavity during a renovation

Type I is easier to prove because the contract itself is the yardstick. Type II has no contract indication to point to, so the contractor has to show the condition was truly unusual for that kind of work in that area.

Notice is where most claims are won or lost

The federal clause requires the contractor to give written notice to the contracting officer promptly, and before the conditions are disturbed. That lets the owner see the condition, test it, and maybe change the design. The clause also bars a request for adjustment made after final payment. Private contracts often add their own short deadlines, sometimes measured in days.

Say an excavation sub on a $2.1 million utility job hits a buried concrete slab 40 feet long that is not on the drawings or the geotech report. The right move: stop digging in that area, photograph it, call the GC's superintendent, and send written notice the same day. The GC passes notice up to the owner. The owner's engineer walks it the next morning, and the sub prices the removal as a change order request with equipment hours, haul tickets, and the schedule impact.

The wrong move is to break it out, haul it off, and send a bill three weeks later. By then there is nothing left to inspect, and the owner will argue it never got a chance to respond.

Common disputes

  • Site investigation clauses. Owners argue the contractor should have found the condition during a site visit. A reasonable pre-bid investigation, documented with photos, is the best defense.
  • Disclaimers on the geotech report. Some contracts say the borings are for information only. How courts treat those disclaimers varies.
  • Late or verbal notice. Under many contracts, notice must be written. A phone call to the owner's rep is not enough.
  • Quantum. Even with entitlement, the contractor has to prove the added cost. Daily logs, time cards, and equipment records carry that proof.

Related terms

See site survey, notice of claim, delay claim, change order, and backfill. Smart Business Automator ties field photos and daily logs to the change order record, which helps when a DSC turns into a change order approval fight.

Frequently asked questions

What is a Type I differing site condition?

A subsurface or latent physical condition that differs materially from what the contract documents indicated, such as rock or groundwater not shown in the borings.

What is a Type II differing site condition?

An unknown physical condition of an unusual nature that differs materially from what is ordinarily encountered in that kind of work, even though the contract said nothing about it.

How fast do I have to give notice?

Under FAR 52.236-2, promptly and before the condition is disturbed. Other contracts set their own deadlines, so read the clause in your contract and give written notice right away.

Does a differing site condition always mean more money?

No. The contractor still has to show the condition differs materially, that it gave proper notice, and what the condition actually cost in time and money.

Sources

  1. Acquisition.gov: FAR 52.236-2 Differing Site Conditions
Written and edited by

Maurice Francois writes and edits construction operations guides for Smart Business Automator. More from Maurice on the Scaling Legends podcast.

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