Whether or not your company remains liable six years after the shingles were installed will  depend on whether the claims raised in the lawsuit are barred by the statute of limitations.If the lawsuit claims breach of contract, your company is liable if the contract was in writing because the applicable statute of limitations in IL is ten years; however, if the contract was oral, your company is not liable because the applicable statute of limitations in IL for breach of an oral contract is five years.If the lawsuit is claiming negligence, your company is not liable because the applicable statute of limitations in IL is five years.A lawsuit is barred if it is filed after the statute of limitations has expired. You can assert the statute of limitations as a defense.A claim of breach of warranty would still be applicable since the manufacturer's warranty is thirty years.  If you are held liable under that claim, you can sue the manufacturer for the amount of the judgment against you.