Janice bought a piece of land, and she wanted to build a house on it. She engaged Perfectionist Contractors ("PC") on 1st January to design and construct the house for her. Under the terms of the contract between Janice and PC, PC has to complete the works by the 30th of June, and the total sum Janice has to pay is $200,000 (with the following breakdown which is specified in the contract: $50,000 for the "design" component and $150,000 for the "construction" component). It is also specified in the contract that the materials used for the floor must be Oak wood with a panel size of 100 millimetres by 300 millimetres. PC started work soon after, and submitted the design proposal to Janice on 1st February which was subsequently approved by her. The design component of the contract was therefore fully completed by PC. However, PC experienced a shortage of manpower during the months of March and April. On 30th of June, PC has only completed 90% of the construction component of the contract. Due to a lack of resources, PC could not continue with the works. Nevertheless, PC felt that it had substantially completed the works and wanted full payment from Janice.

Janice measured the panels used in the flooring and found that they deviated from the contract specifications by up to 2 millimetres. Examine whether the contract has been discharged by performance and conclude whether PC is entitled to any payment for the works it has completed. In your answer, please discuss the precise performance rule and all of the exceptions.