Background
6.The following background to the dispute is drawn from the evidence provided by both parties. As noted above, the application concerns building works the subject of a contract dated 6 January 2011. The contract is a standard residential building contract, pursuant to which Composition Construction was to demolish an existing dwelling and to construct a new dwelling in accordance with identified plans and specifications. The contract price was $625,000.00 payable by way of progress payments to be made upon completion of defined stages of the building works.
7.Sheets 2 and 4 of the original structural plan forming part of the contract documents refer to a "230 Brick Retaining Wall Off Rock 600". The engineering drawings were done by Mr and Mrs Dias' engineer, Mr Chris Morris of CPM Engineering [CPM]. It is common ground that this plan assumed bedrock at a depth of 600 mm upon which the retaining wall was to be built.
8.Composition Construction started the building works in February 2011. The works undertaken were demolition of the existing dwelling, site clearance, installation of footings and pouring of the slab. Mr and Mrs Dias made the claimed progress payments in respect of these stages of the work, with payments totalling $203,125.00.
9.When excavation works were conducted in June 2011, it emerged that there was no bedrock at 600 mm. This meant that the retaining wall contemplated by the structural plan could not be built. Consequently, in July 2011, CPM issued revised plans [the July 2011 revision] in relation to the retaining walls. The July 2011 revision provided two options for building the retaining walls, "RW2" and "RW2 Alternate".
10."RW2" provided for a shotcrete wall over a cut face secured with bolts or anchors. "RW2 Alternate" provided for a besser block wall set with starter bars sunk 450 mm into base rock. Specifications for drainage systems were also provided. The parties agreed to proceed with "RW2 Alternate" and third-party contractors were invited to provide quotes for that option only.
11.On 30 August 2011, Composition Construction advised Mr and Mrs Dias that it could construct the retaining wall for a fixed price of $55,000.00 plus GST. Mr and Mrs Dias were also advised that the work could be done on a costs plus basis for $45,000.00 to $50,000.00 including GST. On 13 September 2011, Composition Construction provided a proposal to undertake "RW2 Alternate" on a costs plus basis and specified rates for various aspects of the work. On 16 September 2011, Mr Dias agreed to this proposal. While the agreement between the parties in relation to "RW2 Alternate" is not in the form of a signed written variation, the parties agree that the agreement constituted a variation of the original contract and not a separate contract. Composition Construction commenced excavation work for the retaining walls on 21 September 2011. No other work was undertaken between 18 October 2011 and 6 February 2012.
12.The retaining wall constructed by Composition Construction is not in accordance with RW2 Alternate. Rather, it is a sandstone gravity wall. Composition Construction claims that while there are no drawings for this style of wall, it was done with the knowledge and approval of Mr and Mrs Dias and of CPM, with Mr Dias purchasing the sandstone for the wall. Composition Construction states that the RW2 Alternate option could not be constructed because bedrock was not found at the depth contemplated by the engineering drawing for that option.
13.Mr and Mrs Dias state that the decision to construct a sandstone gravity wall was made unilaterally by Composition Construction without reference to them or to their engineer and that the only reference to the wall prior to commencing construction was the request to purchase the sandstone blocks.
14.Between 9 February and 1 March 2012, Composition Construction issued invoices to Mr and Mrs Dias in respect of the retaining wall construction. Mr and Mrs Dias paid Composition Construction a total of $30,481.91 in respect of these invoices.
15.On 2 March 2012 a section of the retaining wall under construction collapsed. A site meeting was held on 5 May 2012. Arising from that meeting, CPM issued a further revised structural plan on 29 May 2012 This plan set out a proposed method of completing the retaining walls taking into account the sandstone gravity wall which had been constructed. Mr and Mrs Dias had reservations about the proposal and sought other opinions.
16.In the meantime, on 11 April 2012, Composition Construction issued invoice 897 which was in the amount of $4,776.00. The following day Mr and Mrs Dias advised that they would not make any further payments until the retaining wall had been completed and certified. Composition Construction issued two further invoices (898 and 899) on 17 April and 23 April 2012 respectively, for sums totalling $10,992.10. These invoices were not paid.
17.On 6 June 2012 Composition Construction suspended works on the basis that Mr and Mrs Dias had failed to pay the invoices. On 4 July 2012 Composition Construction purported to terminate the contract for the same reason.
18.Invoices 897, 898 and 899 form the basis of the claim brought by Composition Construction. Composition Construction also claims payments in relation to a water tank and fencing hire, based on the termination of the contract, plus interest and a 10% builder's margin.
19.As noted above, in their cross-application, Mr and Mrs Dias claim that the purported termination of the contract was not valid. They do so on the basis that invoices 897, 898 and 899 were not payable at the time the claim for payment was made. On the basis of their claim that Composition Construction repudiated the contract, Mr and Mrs Dias claim completion costs. They also claim costs to rectify defective work. In relation to this, the evidence filed by Mr and Mrs Dias states that the slab and the retaining walls require replacement. While Mr and Mrs Dias' total claimed losses exceed $500,000.00, they have submitted to the Tribunal's jurisdictional limit.