NZS 3910 Engineers Obligations

Understanding the Engineer's Role Under NZS 3910

Under NZS 3910, the Engineer occupies a unique dual role that is often misunderstood. You are not simply the Principal's representative. You are an independent professional with specific duties to both parties. This independence is crucial to how the contract functions.

The principle that an Engineer or Architect acting as certifier under a construction contract owes a duty of impartiality between the parties is long-established in the common law tradition NZ courts draw on. The leading English authority is Sutcliffe v Thackrah [1974] AC 727, where the House of Lords held that an architect acting as certifier was not protected by quasi-arbitral immunity for negligent certification. The principle has been consistently applied in NZ practice. Pacific Associates Inc v Baxter [1990] 1 QB 993 (English Court of Appeal) further clarified that the certifier's primary duty under the contract is to act fairly between the parties, even though appointed and paid by one of them.

The Engineer's primary function is to administer the contract fairly and professionally. This means making decisions based on the contract terms and professional judgement, not the Principal's commercial preferences. Your NZS 3910 engineers obligations include:

• Administering the contract in accordance with its terms
• Acting fairly and reasonably between the parties
• Making decisions within specified timeframes
• Certifying payments and completion
• Managing variations and claims

Key NZS 3910 Engineers Obligations and Timeframes

NZS 3910 contains specific timeframes for Engineer decisions and approvals. Missing these deadlines can have serious commercial consequences, including deemed approvals and acceleration of payment obligations.

Obligation	Timeframe	Clause Reference
Approval of working drawings	10 working days	Clause 4.4
Response to proposed subcontractors	10 working days	Clause 7.2
Assessment of variation proposals	10 working days	Clause 12.2
Certification of progress payments	5 working days after claim	Clause 11.1
Issue completion certificate	5 working days after achievement	Clause 10.1

These timeframes aren't negotiable under the standard contract. They're designed to maintain project momentum and provide certainty to both parties about decision timing.

Managing Drawing and Design Approvals

One of your most frequent NZS 3910 engineers obligations involves reviewing and approving contractor submissions. Clause 4.4 requires you to respond to working drawings within 10 working days, but there's more nuance here than many realise.

Your approval means the drawings comply with the contract documents. It doesn't mean you're taking design responsibility. That remains with whoever produced the design. However, you are confirming that what's proposed aligns with the contract requirements.

When drawings don't comply, your rejection must be specific. Vague comments like "further consideration required" don't help anyone. State exactly what needs to be addressed for approval, referencing specific contract requirements where possible.

Best Practice for Drawing Reviews

• Establish a systematic review process with your team
• Track submission dates and response deadlines
• Provide clear, actionable feedback on rejections
• Maintain comprehensive records of all approvals and conditions
• Coordinate reviews across disciplines to avoid conflicting comments

Variation Assessment and Approval

Variation management is where many Engineers struggle with their NZS 3910 obligations. Clause 12 gives you broad powers to instruct variations, but these come with corresponding obligations to assess costs and time impacts fairly.

When the Contractor submits a variation proposal under Clause 12.2, you have 10 working days to respond. Your options are:

• Accept the proposal
• Accept the variation but negotiate the price/time
• Reject the proposal entirely
• Request additional information (which may extend the timeframe)

The key challenge is assessing whether the proposed cost and time are reasonable. This requires understanding both the technical requirements and commercial implications. You're not expected to be a quantity surveyor, but you need sufficient commercial awareness to identify unreasonable claims.

Common Variation Assessment Pitfalls

I've seen Engineers make the same mistakes repeatedly when assessing variations:

• Accepting preliminary rates without scrutiny: Contractors often inflate preliminary costs on variations. Challenge these if they seem disproportionate.
• Ignoring programme impacts: Consider how variations affect other work, not just the immediate activity.
• Failing to consider omissions: Many variations involve both additions and deletions. Ensure both are properly valued.
• Not documenting assumptions: Record the basis for your assessment, especially for complex variations.

Payment Certification Under NZS 3910

Payment certification is one of your most important NZS 3910 engineers obligations. Clause 11.1 requires you to certify progress payments within 5 working days of receiving the Contractor's claim. This tight timeframe reflects the importance of maintaining cash flow.

Your certification must be based on work actually executed and materials delivered to site. You're not certifying the quality of work. That's covered separately under the defects provisions. You're confirming that the claimed work has been carried out.

Common certification challenges include:

• Assessing work in progress (particularly earthworks and structural work)
• Valuing materials on site but not yet incorporated
• Dealing with disputed work or variations
• Managing retention and release obligations

Retention Management

Retention under Clause 11.3 is held as security for defects correction. Half is released at completion, half at the end of the defects liability period. Your obligation is to release retention promptly when these milestones are achieved. Holding retention beyond the required periods is a breach of contract.

Completion and Defects Management

Issuing completion certificates and managing the defects liability period are critical NZS 3910 engineers obligations that directly impact project handover and commercial settlement.

Clause 10.1 requires completion to be certified within 5 working days of achievement. This means the works are complete in accordance with the contract, not perfect. Minor defects shouldn't prevent completion certification if they don't affect the works' intended use.

The distinction between completion and perfection is crucial. Completion means:

• The works can be used for their intended purpose
• All contract requirements have been substantially fulfilled
• Only minor defects remain
• Required documentation has been provided

Defects Liability Period

After completion, you manage the defects liability period under Clause 10.3. The focus is on ensuring legitimate defects are identified and remedied. Your obligation is to act reasonably in assessing what constitutes a defect requiring correction.

Record Keeping and Documentation

Comprehensive records are essential for fulfilling your NZS 3910 engineers obligations. Every decision, approval, and instruction should be documented with clear reasoning. This protects both you and your client if disputes arise.

Essential records include:

• All correspondence with dated receipt/issue stamps
• Meeting minutes with clear action items
• Site instruction registers with reference numbers
• Drawing approval registers showing dates and conditions
• Variation instruction records with full commercial details
• Payment certificate registers with supporting valuations

Good record keeping is about creating an audit trail that demonstrates your decisions were made properly and within required timeframes.

Managing Risk and Professional Liability

Your NZS 3910 engineers obligations carry professional liability risks that need active management. These risks arise from delayed decisions, incorrect assessments, and failure to act independently.

Key risk management strategies include:

• Maintain independence: Don't let commercial pressure compromise professional decisions
• Meet deadlines: Late decisions create liability exposure and project delays
• Document reasoning: Clear records support your decision-making process
• Seek advice: Don't hesitate to consult specialists for complex technical or commercial issues
• Professional insurance: Ensure adequate coverage for your NZS 3910 responsibilities