FAR 52.236-2 - Differing Site Conditions (Clause Text)

FAR 52.236-2 - Differing Site Conditions (Clause Text)

As prescribed in 36.502, insert the following clause:

Differing Site Conditions (Apr 1984)

(a) The Contractor shall promptly, and before the conditions are disturbed, give a written notice to the Contracting Officer of-

(1) Subsurface or latent physical conditions at the site which differ materially from those indicated in this contract; or
(2) Unknown physical conditions at the site, of an unusual nature, which differ materially from those ordinarily encountered and generally recognized as inhering in work of the character provided for in the contract.

(b) The Contracting Officer shall investigate the site conditions promptly after receiving the notice. If the conditions do materially so differ and cause an increase or decrease in the Contractor’s cost of, or the time required for, performing any part of the work under this contract, whether or not changed as a result of the conditions, an equitable adjustment shall be made under this clause and the contract modified in writing accordingly.

(c) No request by the Contractor for an equitable adjustment to the contract under this clause shall be allowed, unless the Contractor has given the written notice required; provided, that the time prescribed in paragraph (a) of this clause for giving written notice may be extended by the Contracting Officer.

(d) No request by the Contractor for an equitable adjustment to the contract for differing site conditions shall be allowed if made after final payment under this contract.

(End of clause)

What this clause practically means in federal construction bidding and delivery

FAR 52.236-2 (Differing Site Conditions) is the core risk-allocation clause that makes federal construction bidding less of a gamble when actual site conditions diverge from what the solicitation/contract indicated or from what is normally expected for that type of work. This is why the clause is a frequent trigger for schedule extensions, cost adjustments, and contract modifications in US Government construction contracts.

The clause is built around a simple workflow:

1. Discover a potentially differing condition

   • Either the condition differs materially from contract indications (commonly called Type I in industry practice), or it is unknown and unusual, differing materially from what’s ordinarily encountered (commonly called Type II in industry practice).

2. Notify the Contracting Officer promptly, before disturbing the condition

   • This “before disturbed” language is the operational heart of the clause. The Government needs the condition preserved so it can verify, measure, and document what was actually encountered. If the contractor proceeds and covers it up, removes it, or changes it, the Government can argue it was prejudiced and challenge entitlement.

3. Government investigates

   • The clause requires the Contracting Officer to investigate promptly after receiving notice.

4. Equitable adjustment (EA) if impacts are proven

   • If the condition materially differs and causes an increase or decrease in cost or time, the contract should be modified in writing and an equitable adjustment made.

5. Two key guardrails

   • No notice, no adjustment (unless the CO extends the time for notice).
   • After final payment, you are barred from requesting an equitable adjustment for differing site conditions under this clause.

For RFP and bid teams, the strategic implication is clear: a clean Differing Site Conditions process is a bid strategy advantage. It supports tighter pricing by reducing the need to “pad” subsurface or concealed-condition contingencies when the clause is included and the contract data is credible. For delivery teams, it becomes a discipline: train supers and PMs to treat “prompt notice” and “do not disturb” as mandatory field controls, not paperwork.

Field-ready notice template (copy-paste)

Subject: FAR 52.236-2 Notice of Differing Site Condition – [Project Name / Contract No. / Location]

To: Contracting Officer, [Name] Cc: COR, Resident Engineer, Project Controls, Quality, Safety

Pursuant to FAR 52.236-2, we are providing prompt written notice of a potentially differing site condition encountered on [date/time] at [exact location: stationing/grid/room/area].

Condition observed:

• [Describe what was encountered, objectively. Example: unforeseen rock layer at elevation X; unmarked utility; groundwater inflow; unsuitable fill; concealed structure.]

Basis for differing condition (select one):

• (a)(1) Differs materially from conditions indicated in the contract: [Cite the contract drawing/spec/boring log/reference and explain mismatch.]
• (a)(2) Unknown physical condition of an unusual nature differing materially from ordinarily encountered: [Explain why unusual for this scope/type.]

Immediate actions taken:

• Work in the affected area has been paused/minimized to avoid disturbing the condition.
• Area secured for Government review and measurement.
• Photos, videos, survey shots, and daily reports logged. [List attachments.]

Potential impacts (preliminary):

• Schedule: [anticipated delays/critical path risk if known]
• Cost: [standby, remobilization, dewatering, redesign, additional excavation, etc.]

We request a prompt Government investigation and direction on next steps. We reserve our right to seek an equitable adjustment for cost and/or time impacts resulting from this condition.

Respectfully, [Name, Title] [Contractor Entity] [Phone / Email]

Quick checklist for PMs and site teams

• Capture proof immediately: photos/videos, survey points, quantities, geotech notes, daily report narrative.
• Stop or isolate work in the affected area so the condition is not disturbed.
• Send written notice to the CO fast, with precise location and contract-reference basis.
• Ask for a Government site investigation and written direction.
• Track impacts from day one: labor/equipment standby, resequencing, material waste, subcontractor disruption, testing.
• Push the issue into a formal modification path early, not after the job is closed out.
• Do not wait until the end of the project: paragraph (d) bars requests after final payment.

Sources

• FAR 52.236-2 (Differing Site Conditions) - Acquisition.gov. ([Acquisition.gov][1])
• FAR 36.502 (Prescription for using FAR 52.236-2) - Acquisition.gov. ([Acquisition.gov][2])
• USACE EP 715-1-8 (discussion of FAR 52.236-2 and risk allocation) - U.S. Army Corps of Engineers. ([Army Corps Publications][3])
• Request for Equitable Adjustment (REA) overview - Defense Acquisition University (DAU) Acquipedia. ([Dauphin University][4])
• “Think you have a differing site conditions claim? Proving it is a high bar” - ASCE Civil Engineering Source (Jun 23, 2025). ([asce.org][5])