Exceptions: These are discretionary in nature and must follow the equitable maxim's .
1. Substantial Performance: This is where a contract is performed in all essential respects. The courts may award payments minus any defects.
CASE: "Hoening v Isaacs". In this case a decorator was hired to decorate and furnish a flat for £750, however there were defects which costed around £55. HELD: The contract was substantially performed and the work was still payable. Contrasting ---> CASE: "Bolton v Mahadeva". In this case there was a contract for a central heating system at a cost of £560. The work was done badly and there were defects at around £174. HELD: This wasn't substantial performance ... the exception can't apply as there were defects of £174 ... common law rule applies and payment was denied.AO2: What is substantial is a question of fact, decided on a case-by-case basis. This can lead to uncertainty as the law is unclear. However, justice can be created in individual cases. No criteria is set as it is simply a question of fact.
2. Part-Performance: Payment can be given for the work completed so long as they both agree to the part performance. The "victim of part-performance must have genuine consent to agree". CASE: "Sympter v Hedges". In this case the builder agreed to work for the defendant but abandoned the work without putting the roof on. HELD: There was no true agreement between the parties as the victim didn't accept part-performance as the uncompleted building would have been an 'eyesore' on the land.AO2: This is a fair concept so long as both the parties agree, however it must be a true agreement.