Note
When a Subcontractor Causes a Defect Under Your Warranty
A roofing subcontractor mounted the solar frame. A civil subcontractor laid the cable trench. Your electricians made the connections. Fourteen months later, a factory engineer calls: water has entered the conduit trench and there are fault codes on two inverters.
The fault is in the civil contractor’s scope, not yours. But your company signed the handover document, and your company holds the warranty with the factory. The call comes to you regardless.
This is the subcontractor warranty defect: a fault during your warranty period that originates in work a subcontractor performed on your behalf. How you handle the first call determines whether this is a clean claim or a dispute that ties up a technician for weeks.
Why Does Your Warranty Cover Work Your Crew Did Not Do?
The factory signed a contract with you, not with the roofing sub or the civil sub. One contractor is responsible for the complete installation: you. Your warranty obligation covers the whole scope, regardless of which parts were subcontracted.
This is standard in construction. The main contractor accepts responsibility for the complete installation and manages the risk of the subcontractors they use. A fault in any part of the work comes to you first. The factory does not need to know which sub did which element. That is your problem to manage, and managing it well depends on documentation captured at handover.
How Do You Confirm the Fault Is in the Subcontractor’s Scope?
The triage question before any truck moves: is this fault in a scope that a subcontractor performed?
Pull the site register for this installation. A well-maintained site register records not just what is installed, but who installed it. For a solar project with a roofing sub, the structural mounting is the sub’s scope. The inverters, wiring, and combiner boxes are your team’s scope. The civil trench and conduit is a third sub’s scope.
If the site register does not identify which sub did which element, you are doing the triage from memory or from a project folder months old. That is slower and less reliable.
Worked example. Fourteen months after handover, a Chonburi factory reports fault codes and possible water ingress. The site register records the civil subcontractor’s name, contact, and scope: cable trench and conduit to the inverter room. Your first step is a 20-minute site visit to confirm the trench is the source, not a full repair mobilisation. That visit costs little. Mobilising a repair crew and then discovering it is a sub’s scope costs a day.
What Steps Do You Take Once You Know It Is the Sub’s Work?
Contact the subcontractor and direct them back on-site. You subcontracted this scope and the sub’s work has failed within your warranty period.
Two things to confirm before that call:
- DLP coverage. Does your subcontract agreement include a defects liability period? Most do, typically twelve months from practical completion of the sub’s scope. If you are within that period, you have a contractual path. If you are outside it, you are in a commercial negotiation.
- The sub’s practical completion date. The clock on their DLP starts when they finished, which may be earlier than the project handover date. A sub who finished their scope two months before handover may be outside their twelve-month DLP even if your DLP with the factory still has time left.
State the facts when you call and ask for a response time commitment. Follow up in writing (email or LINE message) and keep a copy.
If the sub attends and rectifies the fault, your obligation to the factory is met at the cost of management time and the diagnostic visit. If the sub disputes their liability, the documentation you have captured is what resolves it.
What Records Do You Need Before Rectification Begins?
Whether the sub is doing the repair or your team is, capture these before work starts:
- Photo record of the fault as found. Dated, site-labeled, taken before any repair work begins. This is your evidence of the condition when the fault was reported.
- A job record entry linking this callback to the specific subcontracted element, the sub’s company name, and the date you contacted them.
- A written response from the sub, even if it is just a LINE message confirming they will attend and when.
If the sub rectifies, get a brief confirmation from your site supervisor that the repair is acceptable.
If you repair it yourself because the sub is unresponsive, record the cost: labor hours, materials, transport. Without that record, you have a grievance but no number.
What If the Subcontractor Will Not Come Back?
The sub may have moved on, the contact number may have changed, or they may dispute the fault falls in their scope. Your options:
- Negotiate the repair cost as a deduction from unpaid sub invoices. If the sub’s retention is still held, this is leverage. Use it before the retention is released.
- Repair it yourself and issue a formal cost recovery claim against the sub. If the sub is a registered company, this is a standard commercial dispute.
- Repair it yourself and absorb the cost. If the cost is modest and the factory relationship matters more than the recovery, this is sometimes the practical answer.
None of these options requires you to delay your response to the factory. The factory called you, and the repair needs to happen. Who ultimately pays for it is a separate question you manage with the sub independently.
FAQ
What If the Sub’s DLP Has Expired but Yours Has Not?
This is the gap that comes from short DLP terms in subcontracts. You still owe the factory rectification, but the sub is no longer contractually obligated to provide it. If the sub is willing to discuss the repair at cost, that may be the fastest path. If not, you carry the repair cost against your own warranty obligation. This outcome is avoidable: write DLP terms into subcontracts that are at least as long as your obligation to the customer.
Who Pays for the First Diagnostic Visit?
In practice, most contractors absorb a short diagnostic visit without claiming it back. The sub conversation starts from a confirmed fault, which is more productive than a disputed one. If the diagnostic takes more than a couple of hours, record the time against the sub claim.
What Should the Site Register Capture About Subcontractors?
For each subcontracted scope: the sub’s company name, the primary contact, the date their work was practically complete, and the DLP period from that date. One row per sub per site. If that record exists, the triage on a warranty callback takes two minutes. If it does not, you are making a phone call to a project manager who may not remember, and searching through a LINE history that dates back eighteen months.
When a subcontracted scope fails, the factory calls you first and who is responsible comes second. TRACE 30 captures subcontractor scope alongside the main installation record so the triage question is answerable before the truck moves. Details at /program/, or book a call at /schedule-a-call/.