Under a standard form lump sum building contract requiring variations to be in writing and signed by both parties, a builder cannot include non-compliant variation claims in progress claims and then terminate for non-payment of those amounts. The formal requirements of the variation clause are conditions precedent to the builder's entitlement to payment, and amounts for non-compliant variations do not form part of the Contract Sum. The authorities holding that progress claims must be paid unconditionally (LU Simon, Concrete Constructions) may be distinguishable where the contract lacks the checks and balances (architect certification, security provisions) present in those cases.
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