Discusses the effects of the limitation acts on clients' claims, with reference to two cases. Describes how the standard forms of building contract contain many clauses requiring the parties to do things within time limits, and this concludes in the issuing of a final certificate. This contains time restrictions which if not challenged in a short period will have deemed to be certified. In "Cantrell and another v Wright and Fuller" ([2003] EWHC 1545 (TCC), [2003] BLR 412) a client was unhappy with a final certificate and claimed that the certificate was invalid because it was issued beyond the contract timetable and certain preliminary steps had not been taken. The judge decided that the time limits imposed by the contract were neither rigid or imputable so the architect had implied power to issue a certificate out of time. In "Merton LBC v Lowe" (CA, 18 BLR 130) the client had asked the architect to delay issuing the final certificate and when it was issued out of time the client argued it was invalid. The CA rejected this arguing that the client could not invalidate the final certificate by its own conduct. Advises that once a certificate is out of time there is an obligation to give notice to both parties before it can be issued. Clients and contractors can make representations about the contents of the certificate but other requirements of the contract are more rigid and immutable.