What is the Defects Liability Period?

The defects liability period (DLP) is the period after practical completion during which the contractor is contractually obliged to return to site and make good any defects that appear in the works.

It is a standard provision in JCT, NEC and most other UK standard form building contracts. The DLP begins on the date of practical completion and runs for the period set out in the Contract Particulars — typically 12 months, though the duration varies by project and contract.

The DLP serves two purposes. For the client, it provides a formal contractual mechanism to require the contractor to return and fix problems that emerge after handover — including issues that were not evident at practical completion. For the contractor, it provides a defined and limited period during which that obligation applies, before the final account is settled and retention is released.

DLP, Rectification Period, Defects Correction Period

The same post-completion mechanism appears under different names depending on the contract form — a common source of confusion:

  • Defects Liability Period (DLP): the traditional JCT terminology, used in JCT contracts up to and including the 2011 editions. Still widely used in practice and in everyday conversation, even on projects using newer contract forms.
  • Rectification Period: the term adopted in JCT contracts from 2016 onwards — including the JCT Standard Building Contract 2016, JCT Design and Build Contract 2016 and their successors. The underlying mechanism is identical to the DLP; only the name changed.
  • Defects Correction Period: the NEC terminology, used in the NEC Engineering and Construction Contract. Under NEC, defects are managed through a slightly different process (the Defects Certificate replaces the Certificate of Making Good), but the principle — a defined period after Completion during which the contractor corrects notified defects — is the same.

For clarity, this guide uses "defects liability period" and "DLP" throughout, as these remain the most widely recognised terms. Where contract-specific terminology is relevant, it is noted.

The DLP and Practical Completion

The defects liability period is triggered by the certification of practical completion. Practical completion is the point at which the works are substantially complete — the building is fit for its intended use — and the employer takes possession.

At practical completion, several things happen simultaneously:

  • The DLP begins
  • The employer takes possession and assumes responsibility for the building's operation
  • The contractor's obligation to insure the works typically passes to the employer
  • Liquidated damages (if applicable) cease to accrue
  • Half of any retention held is released to the contractor

Because practical completion starts the DLP clock — and triggers these other consequences — the date on which it is certified is important. Certifying practical completion prematurely, before the works are genuinely substantially complete, can prejudice the employer's position. Withholding it unreasonably exposes the employer to claims from the contractor. For more on how practical completion is assessed, see our guide to practical completion in construction.

Note that where partial possession is agreed — where the employer takes over a defined section of the works before overall completion — a separate DLP typically runs from the date of possession for that section.

How Long Does the DLP Last?

The duration of the DLP is set in the Contract Particulars (under JCT contracts) or Contract Data (under NEC). It is agreed between the parties at the time the contract is executed and cannot normally be changed unilaterally once the contract is in place.

Typical durations:

  • 12 months is the most common duration for commercial building contracts in the UK
  • 6 months is sometimes used on smaller or simpler refurbishment projects
  • 24 months may be specified on complex or high-risk projects — mechanical and electrical systems, specialist plant, or buildings with demanding performance requirements

On some projects, different elements of the works are given different DLP durations. For example, a complex M&E installation might carry a longer DLP than the general building works, reflecting the time needed to fully commission and test the systems through seasonal variation.

The DLP duration should be considered at procurement stage and agreed in the Contract Particulars before the contract is executed. Once the contract is in place, it cannot normally be extended without the contractor's agreement.

What Counts as a Defect?

Under JCT contracts, a defect is any part of the works that does not conform to the contract — typically because the contractor has used materials or workmanship that do not meet the specified standard. The contractor's obligation is to make the works conform to what was contracted for.

The DLP mechanism does not cover:

  • Fair wear and tear: deterioration resulting from normal use is the employer's responsibility to maintain
  • Damage caused by the employer: if the employer or their tenants damage the works, that is not the contractor's defect to remedy
  • Items excluded from the contract: works outside the contractor's scope
  • Maintenance items: routine maintenance obligations that fall to the employer once they take possession

In practice, determining whether something is a defect (contractor's obligation) or wear and tear / employer-caused damage (employer's responsibility) can be disputed. Clear records, O&M manuals and a well-managed handover process all reduce the risk of these disputes arising.

It is also worth distinguishing between a defect that appears during the DLP and a patent defect that was visible at practical completion but not identified as a snagging item. Both may be covered, but the contractual position differs. For commercial clients, BuildAlliance recommends a thorough inspection at practical completion to capture all visible issues at that stage — see our guide to snagging in construction.

Notifying and Managing Defects

During the DLP, defects are identified through inspection, client feedback and operational monitoring as the building comes into use. When a defect is identified, it should be notified formally to the contractor — typically in writing by the Employer's Agent or Contract Administrator.

The contractor is then required to attend site and make good the defect within a reasonable period. What is "reasonable" depends on the nature and urgency of the defect — an emergency (such as a water leak) warrants a faster response than a minor cosmetic issue.

Good DLP management requires:

  • A clear process for the employer's building management team to report defects to the EA/CA
  • Prompt formal notification to the contractor in the form required by the contract
  • A defects log tracking each item — what it is, when notified, the contractor's response and when resolved
  • Inspection of completed remedial works to confirm the defect has been properly resolved, not just temporarily patched
  • All correspondence and notifications retained as a formal record

The Contractor's Right of Access

The contractor has a contractual right to return to site to make good notified defects. This right should not be denied or frustrated by the employer — for example, by refusing access or by appointing another contractor to fix defects without following the correct contractual procedure. If the employer has defects fixed by a third party without giving the original contractor the opportunity to remedy them, the employer may have difficulty recovering those costs contractually. The correct procedure, where the contractor has failed to respond within a reasonable time, is to follow the mechanism set out in the contract — which may allow the employer to instruct others and charge the cost.

The Schedule of Defects

The Schedule of Defects is a formal document with a specific contractual function under JCT contracts, and it is distinct from the ongoing defect notifications issued throughout the DLP.

Under the JCT Standard Building Contract and JCT Design and Build Contract, the Employer's Agent or Contract Administrator is required to issue a Schedule of Defects not later than 14 days after the end of the DLP (or Rectification Period under 2016 editions). The Schedule lists all defects, shrinkages and other faults that have appeared during the period and which the contractor is required to make good. The contractor then has a specified period — defined in the Contract Particulars — in which to carry out the making good works.

Key points about the Schedule of Defects:

  • It is issued at or shortly after the end of the DLP, not during it — though defects identified during the period should be notified and tracked throughout
  • It consolidates all outstanding defect items into a single formal document
  • The contractor's obligation to make good is triggered by the Schedule — not simply by the employer's complaint
  • It is a distinct document from the snagging list produced at practical completion, which relates to pre-completion items
  • Under JCT, the employer can instruct the contractor to make good defects at any time during the DLP, or alternatively (with the contractor's consent) agree that the defects will not be made good and a deduction will be made from the contract sum instead

Note that under NEC contracts, the equivalent mechanism is the Defects Certificate, issued by the Supervisor at the end of the Defects Correction Period.

The Certificate of Making Good

Once all defects listed in the Schedule of Defects have been satisfactorily rectified, the Employer's Agent or Contract Administrator issues the Certificate of Making Good (referred to in older JCT editions as the Certificate of Making Good Defects).

This certificate is significant because it triggers the release of the second half of any retention held under the contract. Until the Certificate of Making Good is issued, the contractor does not receive the final retention release — giving the employer financial leverage to ensure defects are properly resolved.

Issuing the Certificate of Making Good also effectively marks the end of the contractor's contractual obligation to return and make good further defects under the DLP mechanism. After this point, the employer's recourse for any remaining or newly emerging issues is through the broader legal framework for breach of contract — not through the defects liability period.

The certificate should only be issued once the EA or CA is satisfied that all items in the Schedule of Defects have been properly resolved. Issuing it prematurely — before defects are genuinely made good — can prejudice the employer's position. Under NEC, the equivalent is the Defects Certificate issued by the Supervisor confirming that all notified defects have been corrected.

Retention and the DLP

Retention is a mechanism in most standard form contracts by which the employer holds back a percentage of each interim payment — typically 3% or 5% of the contract value — as security against the contractor's performance. The DLP is directly linked to when retention is released.

Under JCT contracts, retention is typically released in two stages:

  • At practical completion: half of the total retention held is released to the contractor as part of the interim certificate following PC
  • At the Certificate of Making Good: the second half of the retention is released, once all items in the Schedule of Defects have been satisfactorily rectified

The retention mechanism therefore gives the contractor a direct financial incentive to respond to defect notifications and complete the making good process promptly. Conversely, it gives the employer security — a sum held back that provides some protection if the contractor is slow to respond or disputes the existence of defects.

It is worth noting that retention reform has been an ongoing discussion in UK construction. The Aldous Bill and subsequent consultations have proposed a retention deposit scheme to protect contractors in the event of employer insolvency. Clients should ensure their QS advises on retention arrangements appropriate to the current legislative position.

After the DLP: Latent Defects

The expiry of the defects liability period does not extinguish the employer's legal rights in relation to defects. The DLP is a contractual mechanism — a specific right to require the contractor to return and make good. But it sits alongside the employer's broader legal rights for breach of contract, which survive the DLP.

Under English law, a claim for breach of contract must generally be brought within:

  • 6 years of the date of breach, for a contract not executed as a deed (a simple contract)
  • 12 years of the date of breach, for a contract executed as a deed

Most commercial building contracts are executed as deeds, giving the employer a 12-year limitation period. This means defects that emerge after the DLP has expired may still give rise to a valid claim for breach of contract — provided the limitation period has not expired.

Latent defects are defects that were not discoverable at the time of practical completion — hidden structural issues, subsurface problems, or failures within concealed elements of the building fabric. For latent defects, the Latent Damage Act 1986 may extend the time available to bring a claim beyond the standard limitation period, in certain circumstances.

The practical implication for clients is that the end of the DLP is not the end of their rights. However, the DLP is the period during which the most practical and cost-effective mechanism for resolving defects — requiring the original contractor to return and fix them at no additional cost — is available. After the DLP expires, pursuing defect claims typically involves legal proceedings or negotiation, which is more costly and time-consuming than managing defects through the contract during the period.

This underlines the importance of managing the DLP actively and ensuring all identifiable defects are captured and resolved before the Certificate of Making Good is issued.

Common Risks and How to Manage Them

  • Defects not notified in time: once the DLP expires and the Schedule of Defects is issued, new defects emerging after that point fall outside the making-good mechanism. Ongoing active inspection and prompt notification throughout the period are essential.
  • Incomplete or informal records: verbal reporting or informal emails may not constitute valid contractual notification. All defects should be formally notified through the EA/CA in the correct form, with a clear log maintained.
  • Contractor unresponsiveness: if the contractor is slow to respond, the EA/CA should escalate formally rather than wait — the correct contractual procedure should be followed to preserve the employer's rights, including the right to engage others if necessary.
  • Dispute over cause: contractors sometimes resist defect notifications by arguing the issue is fair wear and tear, employer damage or a maintenance item. Detailed photographic records and O&M handover documentation support the employer's position in these disputes.
  • Premature Certificate of Making Good: if the certificate is issued before all defects are genuinely resolved, the employer loses retention leverage and the formal making-good mechanism. The EA/CA should inspect completed works carefully before issuing this certificate.
  • Insolvent contractor: if the contractor becomes insolvent during or after the DLP, the making-good mechanism becomes unenforceable in practice. Collateral warranties from key subcontractors and designers — see our guide to collateral warranties — provide an alternative route to recovery.

Frequently Asked Questions

What is a defects liability period in construction?

The defects liability period (DLP) is the period after practical completion during which the contractor is contractually obliged to return to site and make good any defects that appear in the works. It typically lasts 12 months, though the duration is set in the Contract Particulars and can vary by project and contract form.

What is the difference between the defects liability period and the rectification period?

They refer to the same mechanism. 'Defects Liability Period' is the older JCT terminology. JCT contracts from 2016 onwards renamed it to 'Rectification Period'. NEC contracts use 'Defects Correction Period'. The function — a defined period during which the contractor corrects notified defects — is consistent across all forms.

When does the defects liability period start?

The DLP starts on the date practical completion is certified. It runs from that date for the period specified in the Contract Particulars — typically 12 months.

What is the Schedule of Defects?

The Schedule of Defects is a formal document issued by the EA or CA at or shortly after the end of the DLP. It lists all defects, shrinkages and faults that appeared during the period and which the contractor must make good. It is distinct from ongoing defect notifications issued during the DLP and from the snagging list produced at practical completion.

What is the Certificate of Making Good?

The Certificate of Making Good is issued by the EA or CA once all items in the Schedule of Defects have been satisfactorily rectified. It triggers the release of the second half of retention and marks the end of the contractor's contractual obligation to return and remedy defects under the DLP mechanism.

How does the defects liability period relate to retention?

Retention under JCT contracts is typically released in two stages: half at practical completion, the remainder at the Certificate of Making Good. The contractor's financial incentive to resolve defects is therefore directly tied to the DLP — retention is withheld until defects are properly made good.

Does the contractor's liability for defects end when the DLP expires?

No. The DLP is a specific contractual mechanism; the employer's broader legal rights for breach of contract survive it. Under English law, claims can be brought within 6 years (simple contract) or 12 years (deed) of the breach. Most commercial building contracts are executed as deeds, giving a 12-year limitation period. Latent defects may attract additional time under the Latent Damage Act 1986.

What happens if the contractor fails to return and make good defects?

The employer, through the EA or CA, should follow the contractual procedure — which may allow them to engage others to carry out the remedial works and recover the cost. However, engaging third parties without following the correct procedure may affect the employer's ability to recover costs. The correct contractual steps should be followed before instructing others, and professional advice sought if the contractor is persistently unresponsive.

Reviewed by Scott Edwards, AssocRICS, Director, BuildAlliance — last updated June 2026.

Need Support Managing the Defects Liability Period?

BuildAlliance provides structured Employer's Agent and contract administration support throughout the DLP — from the pre-completion inspection and snagging process, through defect notifications and contractor management, to the Schedule of Defects, Certificate of Making Good and final account.

We ensure the defects process is managed correctly, defects are formally notified and tracked, and the employer's contractual rights are protected through to close-out.

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