Defects Liability Period (DLP)

The defects liability period (DLP) is the contractual phase that follows practical completion of a construction or fit-out project. During this period, the contractor is obligated to return and rectify any defects in workmanship or materials at no additional cost to the client. It provides clients with a structured mechanism to enforce quality standards before the project is formally closed out.

How the DLP Works in Practice

The DLP begins on the date practical completion is certified and runs for a fixed period stated in the contract. For most commercial building projects, this is 12 months. For smaller residential or fit-out contracts, 6 months is common. Complex or high-specification projects - mechanical and engineering installations, specialist fit-out, or infrastructure works - may specify 18 or 24 months.

During the DLP, the client or contract administrator notifies the contractor in writing of any defects that fall within the contractor's scope. The contractor is then required to rectify them within a timeframe set by the contract - typically a defined correction period such as 4 weeks per defect notification. Defects arising from fair wear and tear, misuse by the client, or third-party alterations are not covered by the DLP.

At the end of the DLP, a final inspection is conducted. If all defects have been rectified to the required standard, the contract administrator issues a final completion certificate - called the Certificate of Making Good Defects under JCT contracts, or equivalent under NEC. This triggers the release of any remaining retention funds held from the contractor.

Retention, DLP, and the Two-Stage Release

Retention is the mechanism that enforces the DLP financially. Standard retention in commercial construction is 3-5% of the certified contract sum, withheld in two halves. The first half - typically 50% of total retention - is released on practical completion. The remaining 50% is held throughout the DLP and released only when the final completion certificate is issued.

On a $200,000 contract at 3% retention, total retention is $6,000. At PC, $3,000 is released. The remaining $3,000 stays locked until the DLP ends and all defects are cleared. For contractors operating across multiple projects simultaneously, this second retention pool can represent a significant portion of outstanding receivables - often $20,000-$50,000 or more across an active portfolio.

DLP in Different Contract Frameworks

Under JCT contracts, the term "Defects Liability Period" is used directly. Under NEC contracts, the same concept is governed by the "Defects Date" and "Defect Correction Period." US contracts typically refer to a "Warranty Period" or "Correction Period" under AIA documents. The mechanics are consistent across frameworks: contractor repairs defects, client holds retention as leverage, final certificate closes the contract.

For sub-contractors, the DLP compounds. A main contractor running a 12-month DLP will typically pass through equivalent or extended obligations to their specialist sub-contractors - electrical, mechanical, AV, and specialist fit-out trades. Sub-contractors should confirm their own DLP obligations in writing at appointment and account for potential rectification visits in their project close-out planning.

Zigaflow's project tracking and invoicing tools allow contractors to log DLP end dates and retention balances against individual job records, ensuring final retention invoices are raised on time and the job is fully closed out in the accounting system.