What is a time bar, and why is it dangerous?

A time bar is a clause that can wipe out a right entirely if you miss a deadline for giving notice, however strong the underlying claim is. A notice here just means a formal written message telling the other side something has happened, for example that an event has delayed you or added cost, given within a set number of days. The wording to look for is condition precedent: language saying that giving the notice in time shall be a condition precedent to any entitlement, which is shorthand for you get nothing unless you did this first. Without it a late notice is usually only a procedural slip affecting how strong your evidence looks; with it the claim can be gone the day after the deadline, no matter how good. Short deadlines, strict formats and demands for full details up front make the trap worse, each another way a notice can technically fail. Treat every notice deadline as a hard date and diarise it the day you sign.

Picture a steel frame subcontractor whose contract says any claim for extra time must be notified in writing within seven days of the delaying event, and that giving that notice in time is a condition precedent to any entitlement. A late design change on a Tuesday holds them up for two weeks, a genuine and well documented delay. Snowed under, they send the notice sixteen days later. Because the wording is a true condition precedent, the claim can be gone even though it was real, simply because the seven day window closed. Had the clause lacked that wording, the late notice would more likely have been a black mark against their evidence than a total bar. The strength of the claim never got tested: the calendar decided it.