Note
Defects Period Inspection: Before You Invoice the Retention
The retention release invoice is the last financial step on a closed project. The defects liability period expires, the invoice goes out, the customer pays the withheld percentage. In practice, most customers will not release retention without first confirming the installation is still in good condition. That confirmation does not arrive on its own. It comes from a specific site visit, scheduled before the DLP expires, with a signed document produced at the end.
Contractors who skip this step tend to find out after the invoice is sent, when the customer raises issues nobody reviewed and the retention sits frozen for another month. The defects period inspection puts the contractor in control of timing and evidence.
What Is the Defects Period Inspection?
The defects period inspection is a site visit the contractor schedules approximately three to four weeks before the defects liability period ends. Its sole purpose is to confirm the installation is in the same condition as it was at handover, with all documented defects resolved.
It is distinct from three other visits:
- A warranty callback responds to a reported fault. The defects period inspection is triggered by the calendar, not a fault.
- The annual statutory inspection produces a compliance report for the relevant authority. The defects period inspection produces a defect-clearance document for the customer.
- The handover inspection confirmed the installation met the original scope. The defects period inspection confirms it has been maintained in that condition.
When the DLP expiry falls close to the annual inspection date, combining both visits is efficient. The defect-clearance document is a separate output, signed separately.
Why Should the Contractor Initiate Rather Than Wait?
If the contractor waits for the customer to request the DLP close, two things tend to follow. Many customers will not request it at all, leaving the retention in an ambiguous state where neither side has formally confirmed the conditions are met. When the customer does initiate, they control the framing: any issues accumulated over twelve months arrive as a list the contractor must respond to on the customer’s terms.
Initiating three to four weeks before expiry creates a buffer. A defect found three weeks before the DLP ends is a repair job. The same defect found after the retention invoice is submitted is a dispute. A contractor who confirms quality proactively is also easier to pay than one who submits an invoice and leaves the customer to find their own problems.
What Does the Defects Period Inspection Cover?
The scope depends on installation type, but the structure is consistent.
For all electrical installations:
- Confirm every warranty callback during the DLP is fully documented: fault reported, work completed, customer sign-off on resolution
- Visual inspection of conduit runs, cable management, panel covers, and junction box sealing
- Check for any modifications by the customer’s team or a third party and record them (third-party changes fall outside the contractor’s defects liability)
- Confirm labels, circuit identification, and safety warnings are intact
For solar systems:
- Panel condition: visible damage, soiling, frame integrity
- Inverter status: no active fault codes, cooling path clear, AC and DC connections torque-checked
- Performance note: actual generation during the DLP period compared to the commissioning baseline
For LED retrofit installations:
- Fixture condition: no failed lamps or drivers outside what was already resolved
- Lux spot-check at the measurement points from the commissioning record
- Wiring at accessible junction boxes
A checklist based on the commissioning record works well. The points recorded at handover become the points verified at DLP close.
What Document Do You Need to Produce?
The defects period inspection produces one document: a signed confirmation from the customer’s authorized representative that the inspection was conducted and no outstanding defects were found under the DLP.
It does not need to be long. Four elements are sufficient:
- Site and installation details
- Inspection date
- A statement that the installation was inspected and found free of unresolved defects covered by the DLP
- Signature and printed name of the customer’s representative
This document is the evidence that the retention release condition is met. The invoice issued after it is signed is easier to collect than one sent into a void. It is also the contractor’s evidence if the customer raises a dispute after the DLP has closed.
What If Defects Are Found?
Finding a defect three weeks before expiry is the outcome the proactive timing is designed to produce. Address it before the DLP expires and return for a brief follow-up to confirm the repair. Scheduling ahead gives this room.
If the defect falls outside the contractor’s liability (damage from a forklift strike, a third-party modification, wear from conditions outside the installation scope), photograph it clearly before any work begins and note in the visit record why it falls outside the DLP. The customer’s representative should acknowledge this categorization in writing before the visit is closed.
How Does This Visit Connect to Future Maintenance?
If no maintenance agreement is in place, this is the last scheduled visit under the original contract. It is also the one time in the DLP period when the contractor arrives on site with twelve months of operating data behind them.
For solar: how did generation track against the commissioning baseline? For LED: how many fixtures required attention, and was it within the expected range for the equipment?
That record makes a maintenance conversation specific rather than abstract. The annual statutory inspection falls due within a few months of a 12-month DLP expiry. A service conversation grounded in twelve months of operating evidence is easier to close than one proposed cold.
FAQ
Who Should Sign the Defect-Clearance Confirmation?
Ideally the same person who signed the original handover document. If that person has left, confirm before the visit who now holds authorization to confirm DLP conditions. Arriving to find the right person unavailable wastes a trip and delays the retention invoice.
Does Repairing a Defect Found at the Close Visit Extend the DLP?
Most Thai construction and installation contracts specify that the DLP runs from the handover date to the agreed duration, extended only by a formally issued notice of an unresolved defect. A repair completed within the period and confirmed by the customer in writing meets the condition without extending it. Check your specific contract terms, as language varies.
What If the Customer Raises a Long List During the Visit?
Assess each item: is it a genuine defect within scope, or wear, a third-party modification, or damage outside the DLP? Document the assessment in the visit record. Covered defects should be resolved before the DLP expires. Items outside scope should be recorded with the customer’s acknowledgment.
To see how TRACE 30 builds DLP expiry dates from the site register and flags approaching release dates across your full project portfolio, the program overview is at /program/. If you are carrying outstanding retention on several projects and have not mapped which DLP dates have already passed, a short call at /schedule-a-call/ is a useful place to start.