Defendant posits that the roofing system plaintiff installed "will fail." Moreover, relying principally upon Kusy v. Johnson, 41 Ill. App. 3d 763 (1976), defendant contends that "there can never be substantial performance," where, as here, plaintiff "provided the specifications of the contract and then failed to execute the contract per those specifications." ¶ 26 In Illinois, the long-standing rule in building-contract cases is that a contractor is not required to perform perfectly.

Turning to the issue of plaintiff's damages, the Court observes that the general rule for construction contracts is that when a contractor has performed substantially but has breached "his building agreement by failing to perform [precisely] as required by the specifications . . . then [plaintiff is] entitled to recover the reasonable cost of correcting that default." Kusy v. Johnson, 41 Ill.App.3d 763, 354 N.E.2d 480 (1976); Litwin v. Timbercrest Estates, Inc., 37 Ill.App.3d 956, 347 N.E.2d 378 (1976). Plaintiff contends that under this rule, he is entitled to recover $17,879.82.

Although there was testimony that plaintiffs used the pool to some degree for three years, a setoff for defendant cannot rest upon such a defense where it was not pleaded. To decide otherwise would deprive plaintiffs of the right to notice and opportunity to defend against the issues they must meet. Kusy v. Johnson (1976), 41 Ill. App.3d 763, 354 N.E.2d 480. Defendant contends that the damages awarded are excessive. Examination of the record discloses that the question of the proper measure of damages was given much consideration by the trial court and the parties.

The terms of the contract agreed to by plaintiff were in his form contract. The court's observation in Kusy v. Johnson (1976), 41 Ill. App.3d 763, 766, 354 N.E.2d 480, is applicable here: "* * * We do not accept the contention that a total failure on the part of a building contractor to comply with one of the requirements of written specifications he himself supplied, can in any circumstances, be justly deemed a substantial performance."