Understanding FIDIC Clause 11.6: A Practical Guide To Further Tests In Construction Projects

1️⃣ Purpose of Clause 11.6

Historical Context

• In both 1999 and 2017 editions, Clause 11.6 serves to confirm the proper resolution of defects. The 2017 version slightly clarifies the process and focuses more explicitly on “after remedying” the defects, reflecting FIDIC’s emphasis on well-defined responsibilities and testing obligations.

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2️⃣ Breakdown of Clause 11.6

Below is a simplified breakdown showing how each step would typically unfold under Clause 11.6 in practice:

1. Identification of Defect
   • The Contractor completes remedial work on a defective element of the Works during the Defects Notification Period.
2. Instruction to Perform Further Tests
   • The Engineer issues an instruction for additional or repeated testing (e.g., performance, structural, or operational tests).
3. Cost and Payment
   • If the defect or failure resulted from the Contractor’s default, the Contractor must bear the cost of further tests.
   • If the defect is caused by reasons not attributable to the Contractor’s default, the Employer is liable for the cost, usually handled as a Variation (1999 edition) or similar cost mechanism (2017 edition).
4. Outcome of Tests
   • The Contractor must promptly conduct the tests.
   • If successful, it confirms proper remediation of the defect.
   • If it fails again, further remedial measures or repeated testing can be instructed under the same clause.

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3️⃣ Key Interpretations and Implications

Here are some critical aspects to bear in mind:

• Liability Determination
  • A central question is: “Did the defect arise from something within or outside the Contractor’s control?” This determination directly affects who pays for the further testing.
• Timelines
  • Further tests must occur during or shortly after the relevant Defects Notification Period to ensure timely certification of the Works. Prolonged disputes over test results can push final completion out.
• Risk Allocation
  • The clause effectively places testing risk and cost on the Contractor if the initial defect was the Contractor’s fault. Conversely, if it was an unconnected event, it shifts the financial burden to the Employer.
• Engineer’s Authority
  • The Engineer has a broad right to require repeated testing. This reaffirms the Engineer’s power to ensure that the rectified Works meet contract standards and to specify the required test procedures.
• Contractual Continuity
  • Even after Taking Over (under Clause 10), the possibility of further tests under Clause 11.6 means the Contractor still has obligations. It underscores that acceptance of the Works does not finalize everything if new or recurring defects appear.

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4️⃣ Cross-Referencing with Other Clauses

When thinking about Clause 11.6, it’s not a lonely island within the contract; it forms part of a bigger ecosystem of clauses. Let’s see how it plays nicely (and sometimes forcefully!) with other key provisions:

Clause 9 (Tests on Completion)

• Before Taking Over: Under Clause 9, the Contractor must perform the Tests on Completion to demonstrate that the Works (or a Section) are operational and compliant. This step often occurs right before the Employer issues the Taking-Over Certificate.
• After Taking Over? That’s where Clause 11.6 can swoop in. Imagine you passed the Tests on Completion, but 3 months later, a hidden defect pops up. Once the Contractor remedies that defect, the Engineer might say, “Let’s test that again, just to be 100% sure.” This is where Clause 11.6 steps in and says: “Yes, we can absolutely do additional tests to confirm everything’s truly fixed.”
• Cost Overlaps: The original Tests on Completion typically fall under the original Contract Price, but if these further tests are triggered by the Contractor’s mistake, guess who might have to foot the bill? You guessed it—likely the Contractor. If, on the other hand, it’s a brand-new cause not due to Contractor default, the Employer might share or bear those costs.

Clauses 11.1–11.5 (Defects Liability)

• Overall Defects Liability Framework: Clauses 11.1 through 11.5 tell us how the Contractor must address defects and who typically covers the cost. Then comes Clause 11.6—it’s almost like the final “double-check” button. After you’ve fixed the defect (under, say, Clause 11.2 or 11.4), the Engineer can say, “Cool—now let’s re-test to confirm the fix.”
• Defects Notification Period and ‘The Clock’: These earlier clauses define how long the Employer can keep pointing out defects. Picture a timer that starts upon Taking Over. Clause 11.6 says, “I don’t care if we’re near the end of that Defects Notification Period—if you found the defect, fixed it, and I think we need more testing, we can do it.”
• Cost Trigger: If the remedial works under Clause 11.2 (Cost of Remedying Defects) or Clause 11.4 (Failure to Remedy Defects) are squarely due to the Contractor’s poor workmanship, the subsequent “further tests” of Clause 11.6 likely land on the Contractor’s balance sheet. But if the blame (or risk) belongs to the Employer, it’s typically an instruction entitling the Contractor to additional compensation.

Clause 8 (Commencement, Delays, and Suspension)

• Potential Time Extensions: The big question is, “What if these further tests cause delay?” Under Clause 8.4 (1999) or 8.5 (2017), the Contractor might argue that testing has set them back if the fault wasn’t theirs.
• Suspension for Safety or Testing: If a defect is serious enough to require partial shutdown (think structural integrity concerns), the Engineer might invoke suspension under Clause 8.8 or 8.9. Then, once remedied, testing under Clause 11.6 could be the final step to lift that suspension.

Clause 10 (Taking Over)

• You’re Not Off the Hook Yet! Once the Employer issues a Taking-Over Certificate under Clause 10, the Works are considered taken over. But it doesn’t mean everything is final. If a hidden defect arises during the Defects Notification Period, the Employer can still insist on remedial works, and the Engineer can still say, “Prove it’s properly fixed,” by leveraging Clause 11.6.
• Interplay with Partial/Sectional Taking Over: In many projects, the Employer might take over sections or parts in stages. The same principle applies: if a taken-over section develops a defect, the Contractor can be asked to remedy and re-test that specific area.

Clause 13 (Variations and Adjustments)

• Variation or Not? Under the 1999 edition, if the further tests are required due to a defect not caused by the Contractor, this action can be treated as a Variation. Why? Because it’s new or additional work not originally contemplated. That means the Contractor could get additional payment and possibly time.
• Mechanics in 2017 Edition: Although the concept is largely the same in 2017, the wording is more explicit. It still emphasizes that if you’re incurring extra cost for reasons beyond your control, you’re usually entitled to Variation-like compensation. But if it’s your own fault, you don’t get to wave that Variation flag for free money.

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Making Sense of the Bigger Picture

Clause 11.6 doesn’t exist in a vacuum. Think of it as a puzzle piece, fitting snugly with the other clauses to form a seamless path from “identifying a defect” (Clauses 11.1–11.5) to “fixing it” to “verifying via further tests” if there’s any doubt. Meanwhile, Clause 8 can handle any ripple effects on deadlines, and Clauses 9 or 10 frame how the testing might differ from earlier mandatory checks or from taking over. If it’s extra or unexpected, Clause 13 explains who pays.

This synergy is what makes the FIDIC framework robust: it ensures each step from defect detection to final confirmation is neatly governed, giving both parties a predictable way to address and finalize potential issues.

So, next time someone wonders, “Why bother with re-testing once the defect is corrected?” Clause 11.6 and its bedfellows have you covered!

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5️⃣ What If Scenarios?

Here are hypothetical illustrations of how Clause 11.6 might operate:

1. 🚨 Defective Turbine Shaft
   • During the Defects Notification Period, the shaft fails to meet performance requirements. The Contractor repairs it. The Engineer requests repeated performance tests to confirm the fix.
   • If the original defect was due to poor workmanship, the Contractor bears all repeated test costs. If it was due to a design change initiated by the Employer post-Contract signing, the Employer reimburses the testing costs.
2. 📌 Intermittent Software Glitch
   • Under a design-build scenario, the Contractor fixes a software bug discovered by the Employer. The Engineer demands re-verification tests. If it turns out the root cause was incorrectly communicated requirements from the Employer, it might fall under the Employer’s liability. Otherwise, the Contractor pays.
3. ✅ Minor Structural Crack
   • The Contractor patches up a hairline crack in a concrete column that appears during the DNP. The Engineer orders non-destructive testing to ensure there are no hidden structural issues. This cost typically remains with the Contractor if it was a workmanship flaw; if it was an unforeseeable ground movement, it may be the Employer’s expense.

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6️⃣ Suggestions for Clarity and Improvement

Let’s dive deeper into ways you can enhance Clause 11.6 (Further Tests) for your specific project needs, focusing on both practical suggestions and possible wording tweaks.

1. Be Precise About the Nature and Scope of “Further Tests”

Problem: The clause simply says “Engineer may instruct further tests.” But what kind? And how extensive? This is vague and opens the door for inconsistent interpretation.

Real Example:
Imagine a sewage pump system has a minor vibration issue after repair. The Engineer insists on repeating the entire commissioning test cycle, including pressure, flow, electrical, and acoustic testing—costing days of time and equipment rental. The Contractor expected only vibration checks.

Improvement Strategy: Add precision to the term “further tests”—specify whether it refers to:

• Full repetition of initial Tests on Completion,
• Targeted tests only on remedied components,
• Independent third-party validation.

📄 Suggested Wording:

“The Engineer’s instruction under Sub-Clause 11.6 shall specify whether the further tests are (i) full repetition of Tests on Completion, (ii) partial tests relevant to the defect, or (iii) specialized diagnostic procedures. Unless otherwise stated, further tests shall be limited to the systems or components affected by the defect.”

2. Clarify Payment Responsibility and Cost Allocation

Why? Clause 11.6 in the standard text typically says if the defect is the Contractor’s fault, the Contractor pays for further tests, otherwise the Employer pays. But “fault” can be murky, and real-world complexities (like partially defective Employer’s-supplied materials) muddy the waters.

Example Scenario:

• The Employer supplies a special coating. If this coating fails, is it the Contractor’s responsibility (application error) or the Employer’s (material defect)? Clear language can prevent arguments later.

Suggested Wording:

“If further tests are required under Clause 11.6, and the cause of the defect is determined by the Engineer to be attributable to:

• Contractor’s default, the Contractor shall bear all costs of test preparation, execution, and reporting.
• Unforeseeable conditions, errors in the Employer’s design, or Employer-supplied materials, the Employer shall reimburse the Contractor for all reasonable costs (including testing fees, labor, and relevant overhead) within 28 days of the Engineer’s certification.”

3. Integrate with Clause 8 (Time) and Scheduling Implications

Why? Re-testing might cause a short schedule disruption or lead to a more prolonged delay if the defect is significant. Clause 8 deals with extension of time, so linking Clause 11.6 to Clause 8 ensures everyone is on the same page about timeline adjustments if further tests become more extensive than anticipated.

Example Scenario:

• After the Contractor repairs a crack in a key structural beam, the Engineer wants thorough load tests. Those tests require partial site closure for safety. The closure might affect the Work’s overall completion schedule—leading to possible extension-of-time considerations.

Suggested Wording:

“The Parties acknowledge that any further tests conducted under Clause 11.6 may necessitate partial or full suspension of Works to ensure safety and proper testing conditions. In such cases:

• The Contractor shall be entitled to an extension of time under Clause 8 if the delay is not due to Contractor default.
• Where partial suspension is mandated by the Engineer, costs and time impacts shall be assessed in accordance with Sub-Clauses 8.9–8.12, including potential adjustments to the Time for Completion.”

This ensures you don’t accidentally penalize the Contractor (or the Employer) for test-related slowdowns where fault is not clearly the Contractor’s.

4. Reference Local and/or Project-Specific Codes & Standards

Why? FIDIC is intentionally international, but localizing your Particular Conditions ensures the contract aligns with the standards or codes typical in your region, such as IS codes in India, British Standards (BS), Eurocodes, or ASTM in the U.S.

Example Scenario:

• A project in India might specify using Indian Standards (IS) for concrete compressive strength testing or Indian Road Congress (IRC) guidelines for road load testing.

Suggested Wording:

“All further tests required under Clause 11.6 shall comply with relevant Indian Standards (IS) and shall be conducted by laboratories accredited by the National Accreditation Board for Testing and Calibration Laboratories (NABL), unless otherwise agreed by the Engineer.”

5. Encourage or Mandate Preventive Maintenance and Early Checks

Why? Some defects or issues can be caught early with periodic checks during the Defects Notification Period. This approach lowers the chance of large-scale re-tests if the problem is identified quickly and fixed in a less disruptive manner.

Example Scenario:

• An HVAC system might require monthly performance logs to watch for anomalies in airflow or temperature consistency. If you detect a small variance early, remedial works and subsequent tests are far less invasive than discovering catastrophic failure at the tail end of the DNP.

Suggested Wording:

“The Contractor shall conduct periodic inspections or preventive maintenance measures during the Defects Notification Period as specified in [Schedules / Employer’s Requirements]. If any potential defect is found, the Contractor shall promptly notify the Engineer, propose corrective measures, and perform further tests as may be instructed under Clause 11.6.”

6. Propose a Clear “Trigger Mechanism” for Further Tests

Why? Right now, Clause 11.6 is mostly about what happens after you discover a defect. However, sometimes the Engineer, or even the Employer, may suspect a potential defect but it’s not yet confirmed. Introducing a “trigger mechanism” clarifies how the Engineer’s instructions are triggered and documented.

Example Scenario:

• The Engineer notices unusual vibration in a generator but is not certain if it’s a “defect” or normal wear. The contract can let the Engineer order preliminary checks, and if the checks confirm a defect, you move into the official Clause 11.6 procedure.

Suggested Wording:

“In cases where the Engineer suspects a concealed or incipient defect, the Engineer may instruct the Contractor to perform preliminary diagnostic tests. If such tests reveal a defect, the Engineer may then issue an instruction under Clause 11.6 for full-scale further testing and/or remedial works, in accordance with the cost allocation principles stated herein.”

7. Include Example Test Reports or Forms in an Annex

Why? Standardized forms or checklists make it easier for all parties to know what information should go into the test report and how results are evaluated.

Example:

• A short “Test Report Form” annex might have sections for date/time, environmental conditions, references to relevant standards, test methodology, measured values, pass/fail criteria, and sign-offs by Contractor and Engineer.

Suggested Wording:

“All results of further tests under Clause 11.6 shall be compiled in the standardized Test Report Form included in Annex X to the Particular Conditions. Reports shall identify the root cause of the defect, method of repair, test methodology, acceptance criteria, and final outcomes, duly signed by the Contractor and countersigned by the Engineer.”

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Pulling It All Together

Clause 11.6 can be deceptively short, but adding clarity to how, when, and why further tests occur—and who bears the costs—can prevent many headaches. Whether it’s adopting local standards, setting definite test procedures, or explicitly tying further testing to time and cost outcomes, small contractual tweaks pay big dividends.

By embedding clear processes and practical language—like the sample wording above—into your Particular Conditions, you ensure that Clause 11.6 acts as a helpful safety net rather than a constant source of dispute.

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7️⃣ Final Takeaways

1. Ongoing Obligations: Clause 11.6 in both editions confirms that the Contractor’s obligation to prove that remedial works are satisfactory does not end once a defect is superficially fixed.
2. Fault-Based Cost-Sharing: Whoever is responsible for the defect generally bears the costs of any further tests, promoting diligence in both design and workmanship.
3. Engineer’s Leverage: This clause endows the Engineer with significant power to call for testing, ensuring that unresolved or latent issues are identified before the performance certificate is issued.
4. Proactive Coordination: Contractors benefit from preemptive alignment with the Engineer regarding test standards, particularly if remedying defects might require repeated testing.

By understanding Clause 11.6—and cross-referencing it with related clauses on defects liability, variation procedures, and cost responsibility—both Employers and Contractors can navigate the final verification stages more confidently and reduce disputes over remedial works and associated test expenses.

📋 Clause 11.6 – Compliance Checklist

S. No.	Checklist Item	Applicable Clause Reference	✓
1️⃣	Has a defect been notified during the Defects Notification Period?	Clause 11.1 / 11.2	☐
2️⃣	Has the Contractor completed the remedial work for the defect?	Clause 11.2	☐
3️⃣	Has the Engineer issued a written instruction for further tests under Clause 11.6?	Clause 11.6	☐
4️⃣	Does the instruction clearly state the scope and type of tests (full, partial, or specific)?	Clause 11.6 (modified via Particular Conditions)	☐
5️⃣	Have applicable testing standards (IS/IEC/ISO/etc.) been identified or referenced?	Employer’s Requirements / Technical Specs	☐
6️⃣	Has the Contractor submitted a test method statement for Engineer’s approval?	Clause 11.6 + Procedural Add-on	☐
7️⃣	Was the test method reviewed and approved/commented on within the specified timeline?	Clause 11.6 + Procedural Add-on	☐
8️⃣	Have all necessary safety, access, and isolation measures been implemented for testing?	Safety Provisions / Method Statements	☐
9️⃣	Was the test conducted within the specified duration and under defined conditions?	Clause 11.6	☐
🔟	Was a formal test report prepared using the approved format or template?	Annex to Particular Conditions	☐
1️⃣1️⃣	Did the Engineer certify or reject the test results within the agreed timeframe?	Clause 11.6	☐
1️⃣2️⃣	Was the cost responsibility (Contractor or Employer) determined and recorded based on fault?	Clause 11.6 + Cost Allocation Add-on	☐
1️⃣3️⃣	Was any schedule impact due to testing evaluated under Clause 8 for possible EOT?	Clause 8.4 / 8.5 (1999 / 2017)	☐
1️⃣4️⃣	Was any cost implication due to testing processed through Clause 13 as a Variation?	Clause 13	☐
1️⃣5️⃣	If a dispute arose, was the matter referred to the Clause 20 dispute resolution procedure?	Clause 20	☐

✉️ Sample Letter 1: Engineer Instructing Further Tests After Remedial Works

Scenario: The Engineer instructs further testing after the Contractor has carried out remedial works on a defect.

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To:
The Contractor
[Contractor Name]
[Address]
[Date]

Subject: Instruction to Conduct Further Tests Under Sub-Clause 11.6 – [Project Name]

Dear Sir/Madam,

Pursuant to Sub-Clause 11.6 [Further Tests] of the Conditions of Contract, and following the completion of remedial works carried out on [description of the defect and location], you are hereby instructed to conduct further tests to verify that the remedial works have restored compliance with the Contract requirements.

The scope of the required tests includes the following:

• [Brief description of the tests: e.g., Load Testing on Beam B12, NDT on repaired welds]
• Test Standards to be followed: [e.g., IS 516, ASTM E165]
• Test Date/Duration: [Insert proposed dates or timeline]
• Witnessing Requirements: [e.g., Engineer’s Representative must be present]

Please submit your test method statement and schedule within [X] days for review and approval.

If these further tests confirm satisfactory compliance, no further action shall be required. If non-compliance is confirmed, additional remedial works may be instructed as necessary.

Yours faithfully,
[Engineer’s Name]
Engineer
For and on behalf of the Employer

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✉️ Sample Letter 2: Contractor Responding to Engineer’s Instruction to Test

Scenario: Contractor acknowledges the instruction and submits method statement or schedule.

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To:
The Engineer
[Engineer’s Name]
[Address]
[Date]

Subject: Acknowledgment and Submission of Test Method Statement – Clause 11.6

Dear Sir/Madam,

We acknowledge receipt of your letter dated [Insert Date] regarding the instruction for further tests under Sub-Clause 11.6 of the Contract in relation to the remedial works completed at [Location/Component].

Please find enclosed our proposed Test Method Statement and testing schedule for your review and approval. The tests will be conducted as per the applicable standard [Insert Standard Reference] and in accordance with your instruction.

We propose to commence testing on [Insert Date], subject to your confirmation and approval of the method statement.

Kindly confirm your availability for witnessing the test and provide any further instructions or comments.

Yours faithfully,
[Your Name]
For and on behalf of [Contractor’s Company]

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✉️ Sample Letter 3: Contractor Disputing Test Scope or Cost Allocation

Scenario: Contractor disagrees with either the scope of the test or who should bear the cost.

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To:
The Engineer
[Engineer’s Name]
[Address]
[Date]

Subject: Clarification/Dispute Regarding Further Tests under Sub-Clause 11.6

Dear Sir/Madam,

We refer to your instruction dated [Insert Date] under Sub-Clause 11.6 regarding further tests following remedial works completed on [Component/Section].

We respectfully submit that the defect in question was not caused by any act, omission, or fault on the part of the Contractor but instead resulted from [Employer-Supplied Material / Unforeseeable Conditions / Force Majeure Event].

Accordingly, and in line with the risk allocation principles under the Contract, we believe that the cost for such further tests should be borne by the Employer and not the Contractor.

We request the matter be clarified in writing. Should the issue remain unresolved, we reserve our rights under Sub-Clause 20.2 (Claims) and shall consider referring the matter to the Dispute Avoidance/Adjudication Board as per Clause 20.

Yours faithfully,
[Your Name]
For and on behalf of [Contractor’s Company]

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✉️ Sample Letter 4: Engineer Certifying Successful Test Completion

Scenario: The Engineer certifies that further tests have confirmed compliance post-remedy.

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To:
The Contractor
[Contractor Name]
[Address]
[Date]

Subject: Certification of Further Tests – Clause 11.6

Dear Sir/Madam,

Following the further tests conducted on [Insert Date] in accordance with Sub-Clause 11.6, we confirm that the remedial works performed on [Component/Section] have restored compliance with the Contract requirements.

The test results, as recorded in the submitted Test Report dated [Insert Date], are satisfactory and meet the acceptance criteria outlined in [insert relevant test standard or Employer’s Requirements].

No further action is required in respect of this defect.

Yours faithfully,
[Engineer’s Name]
Engineer
For and on behalf of the Employer