Defects Liability Period (DLP)

The defects liability period (DLP) is a fixed contractual timeframe that starts at practical completion and runs until the client formally confirms all identified defects have been rectified. During this period, the contractor is required to return to site and fix any defects arising from their workmanship or materials, at no additional cost to the client. On most standard UK contracts - including JCT and NEC - the DLP runs for 12 months by default, though the duration can range from 6 to 24 months depending on the contract and the nature of the works.

What Happens During the DLP

When a project reaches practical completion, the client takes possession and the building or installation goes into operational use. The DLP clock starts at that point. If the client identifies a defect in the contractor's workmanship or the materials used, they notify the contractor in writing, and the contractor must return to fix it without raising a charge.

The DLP covers genuine defects - failures arising from poor workmanship or substandard materials. It does not cover damage caused by the client, normal wear and tear, or changes made since practical completion. The contractor retains the right to inspect any reported defect before committing to a repair, and can contest notifications they believe fall outside their liability.

At the end of the DLP, the contract administrator issues a Certificate of Making Good (under JCT) or a Defects Certificate (under NEC4). That certificate is the contractual trigger for releasing the second half of retention - the portion held since practical completion.

The DLP and Retention Release

The DLP is inseparable from retention. On a typical UK construction contract, 5% retention is withheld during the works. At practical completion, half is released - giving the contractor 2.5%. The remaining 2.5% is held until the DLP ends and all defects are certified as made good.

On a £500,000 contract, that means £12,500 sits in the client's account for the full DLP duration. On a £2,000,000 contract, it is £50,000. If the DLP end date is not logged and the retention invoice is not raised at the right time, that sum goes unbilled for longer than necessary - or gets missed entirely.

The practical discipline is simple: log the DLP end date in the job record at the same time as the practical completion date. Many contractors track PC but add the DLP end date later - by which point it is easy to lose track of. Setting a 30-day advance reminder means the final retention invoice goes out at the right time without relying on anyone's memory.

Zigaflow's project tracking allows DLP end dates to be recorded as milestones against a job, with the final retention invoice ready to raise when that trigger date arrives.