Managing Your Defects Liability Period on Schedule

What is a defects liability period — and why it catches contractors off guard

A defects liability period, or DLP, is the time after practical completion during which the contractor must return to fix defects in the finished work. In Thai construction contracts, the DLP commonly runs from one year for homes and renovations up to two years for commercial builds — and some government contracts specify three. The problem for most SME contractors is not the obligation itself but the planning: handover feels like the finish line, so the DLP gets no schedule. Defect calls arrive unexpectedly, repair crews go out without a record, and when the owner asks whether the warranty is still running, nobody has a clear answer. Treating the DLP as a planned phase on the Gantt — not kept only in memory — means you control the timeline instead of reacting to it.

How long is a typical DLP in Thai construction contracts?

For private residential work in Thailand, a one-year DLP from the formal acceptance date is standard. Commercial contracts commonly use one to two years depending on MEP complexity and negotiation. Government projects under Thai public procurement rules typically require two years, and specialist infrastructure may specify longer. The critical point is that the DLP clock starts on the documented handover date — not when the contractor believes they are done. If formal acceptance slips two months past the planned finish because the punch list dragged on, the DLP starts two months later as well. Every week you delay the formal close extends the period of uncertainty — another reason to drive the punch list to completion quickly and get the sign-off in writing.

Why should DLP milestones go on your Gantt chart?

When the DLP is not on the schedule, it becomes invisible. You know roughly when the warranty ends — perhaps — but there is no plan for proactive visits, no assigned person to track defect calls, and no record of when repairs happened. The first sign something is wrong usually comes from the owner, not the schedule. Adding three milestones to the Gantt planning view changes this: a DLP start milestone at the formal handover date, a mid-DLP check visit at the halfway point, and a DLP end milestone when the obligation closes. You can attach a preparation task to each, assign it to the right person, and see it alongside the rest of the timeline. The mid-DLP visit catches small defects before the owner compiles a longer list near year's end.

What should a mid-DLP proactive visit look like?

About four to six months into the DLP, before the owner begins their own end-of-warranty walkthrough, send the site supervisor or a qualified crew member back for a proactive inspection. The aim is to find and fix small issues — a door that has started to stick, hairline cracks in plaster, sealant that has shrunk — before they become a formal complaint. Log each finding through the on-site progress update feature: photograph the defect, note the location and the fix, and mark the visit complete. This builds a contemporaneous record showing the contractor actively managed the warranty rather than waiting for calls. On projects where the final retainage is tied to DLP expiry, this documented care often prevents the owner from finding grounds to delay the release.

A worked example: DLP on a 4.8 million baht commercial fit-out in Nonthaburi

Khun Nattapong completes a 4.8 million baht commercial fit-out for an office in Nonthaburi on 12 March 2026. The contract specifies a one-year DLP with 5% retainage — 240,000 baht — held until the period expires. He adds three milestones to SiteBoard: DLP Start on 12 March 2026, Mid-DLP Visit on 12 September 2026, and DLP End on 12 March 2027. In August he assigns the mid-visit to his site supervisor with two weeks' preparation time. The September visit finds two issues: a bathroom exhaust fan vibrating and a ceiling tile shifted. Both are fixed in one day and logged with before-and-after photos through on-site progress updates. When March 2027 arrives, no outstanding claims remain and the 240,000 baht retainage is released without dispute. Without the milestone and the mid-visit, those issues would likely have surfaced in February as a longer complaint list — too close to the DLP end to resolve cleanly.

How should you document each repair visit during the warranty period?

Documentation is the difference between a warranty period that closes cleanly and one that becomes a dispute. For every repair visit, record the date, who attended, what was reported, what was done, and the before-and-after condition. The on-site progress update feature in SiteBoard is the right tool: add a progress note to the relevant task, attach two photographs — defect as found and repair completed — and log the date. This creates a timestamped record that is harder to dispute than a LINE message or a voice note. If the owner later claims a repair was never completed, the dated photo record is your evidence. If a fresh issue appears caused by tenant modifications after handover, earlier inspection records help establish that context.

How does the owner sharing link help during the DLP?

When DLP milestones are in SiteBoard and the owner holds the link from the owner sharing feature, they can see the DLP end milestone on the live schedule at any time. This removes one of the most common friction points of the warranty period: the owner who insists the warranty runs longer than the contract states. With the DLP end date visible on the shared schedule and traceable to the formal handover milestone, the conversation moves from disagreement to both parties looking at the same documented date. For contractors holding a final retainage payment until DLP expiry, the milestone also signals to both sides exactly when the release is due — no ambiguity about the trigger date, no need to chase for an acknowledgement.

What counts as a warranty defect versus fair wear and tear?

A warranty defect is a failure in materials or workmanship with its root cause in the original construction. A crack that appears because a wall was under-reinforced is a defect. Paint scuffed by daily use is not. Sealant that failed because it was applied too thin is a defect; sealant that degraded after two years of direct sunlight on a west-facing facade may not be. The best protection is to document the finished condition at handover — photographs, the signed punch list, and the formal acceptance date — giving you a baseline against later claims. When a claim arrives during the DLP, inspect promptly, photograph in context, and record the probable cause in writing before agreeing to repair. A note written on the day of inspection carries far more weight in a dispute than a recollection months later.

FAQ: What if the owner makes a defect claim after the DLP has expired?

Once the DLP ends and the formal acceptance was given, the warranty obligation under the contract has closed. Claims after that point are the owner's responsibility or fall under a separate maintenance agreement if one exists. Check the DLP end milestone in the schedule, let the owner see the same date via the shared link, and explain calmly that the period has ended. Most owners who make post-DLP claims simply forgot when the warranty expired — they are not usually acting in bad faith. Acknowledging the issue, citing the documented end date, and offering a separate paid maintenance visit is almost always a better outcome than a dispute that damages a relationship that may lead to future work or a referral.

FAQ: Do subcontractors carry their own warranty obligations?

Yes — and this matters for your costs. When you engage a subcontractor for waterproofing, electrical installation, or air conditioning, their work typically carries a warranty clause in your sub-contract, separate from the DLP you hold with the owner. If a waterproofing failure appears eight months into the DLP, check whether it falls under the sub's own warranty before absorbing the repair cost yourself. Keep a note against each sub in the project record showing their warranty duration and contact details. When a defect call arrives, identify which trade's scope it falls under before deploying your own crew. Managing subcontractors through the Gantt planning view — with tasks logged by trade — makes this lookup far faster than searching through paper contracts filed months earlier.

FAQ: Must retainage be held for the full DLP before it can be released?

This depends on the contract terms. Some contracts tie retainage release to practical completion followed by a defects-free period of, say, six months — not necessarily the full DLP. Others hold the full amount until the period expires with no outstanding claims. Read the release trigger carefully and add it as a specific milestone on the Gantt so you know exactly when to request payment. If the trigger is six months after the last resolved defect, that date shifts with each new claim — update the milestone accordingly. Some owners split retainage: half at handover, half at DLP end. In that structure each half becomes its own payment milestone. Making these milestones visible on the shared schedule reduces the friction of chasing the owner for each release.