Cover shortfall and price escalation on a school seismic retrofit
A school seismic retrofit in Sevan is under a unit-price contract of 480 million AMD with an 8% contingency. The contractor is nine weeks behind schedule. Rebar prices have risen 22% since tender, and the contractor claims the difference as an extra. Technical supervision has measured beam cover at 18 mm where the specification requires 25 mm, although the concrete strength passes. The contractor argues that the cover difference is minor and asks for certification of the next payment so that work can continue. The municipality wants the school open for the September term and pressures the supervisor to sign.
1. Should the supervisor certify the payment and accept the cover shortfall? Give the reasoning and conditions.
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The supervisor should not certify the affected work as compliant while a specified durability requirement is unmet. Cover is not cosmetic: at 18 mm instead of 25 mm, carbonation and chloride penetration reach the reinforcement sooner, and fire resistance is reduced. Passing concrete strength does not cure a cover deficiency. The correct step is to issue a nonconformance report, withhold the value of the affected beams, and require an assessment by the designer. Acceptable remedies may include additional protective measures only if the designer demonstrates equivalent durability and fire performance; otherwise the beams must be recast or augmented. Certification of other conforming work can continue separately. Signing the whole payment to meet the September opening would convert a technical nonconformance into a documented acceptance, and the supervisor would lose the ability to require remediation later.
2. How should the contractor's 22% rebar escalation claim be handled under a unit-price contract with contingency?
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The claim must be tested against the contract's price-adjustment mechanism. A unit-price contract fixes rates unless it contains an escalation or indexation clause; a general rise in market prices is normally the contractor's risk. The 8% contingency is for authorised scope changes or quantified risks defined in the contract, not an automatic price-increase fund. The contractor should submit the price index, quantities affected, invoices and the contractual basis. If the contract has no adjustment clause and the rise is ordinary market movement, the claim should be rejected. If the rise results from a delayed employer decision or a variation, only the affected quantities and period should be evaluated. Any approved amount must be processed as a formal contract amendment, not paid from contingency without documentation.
3. Propose a recovery plan that protects both the structural works and the school opening date.
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Separate the schedule into compliant and nonconforming zones. Complete and certify the areas unaffected by the cover issue so that the programme advances. For the affected beams, obtain the designer's written remediation within a fixed number of days, then schedule the repair or recast as a critical activity. Increase supervision frequency at those locations and require hold points before concealment. For the opening date, identify temporary accommodation or partial-use options that do not rely on uncertified structure. Do not allow the contractor to trade away cover compliance for programme. Update the risk register, notify the municipality in writing of the technical basis for any delay, and keep a daily record of instructions and site conditions so that responsibility for the delay can be assessed later.