When a mechanical contractor leaves a construction project before completing their work, builders can be left managing more than an unfinished HVAC installation. Outstanding mechanical services, construction defects and unresolved coordination issues can affect other trades, disrupt the construction programme and complicate compliance requirements.
The immediate challenge is to establish what has been completed correctly, what needs rectification, and how the remaining work can proceed without further delays.
For builders and developers, a structured recovery approach can help identify issues, clarify responsibilities, and establish a practical path to completing the mechanical services package.
What Happens When a Mechanical Contractor Leaves a Project Unfinished?
Mechanical services are closely connected to other building systems. Ductwork, refrigerant pipework, ventilation equipment and electrical controls must often be installed alongside structural, hydraulic, electrical and fire services.
When a contractor leaves partway through construction, the impact can extend beyond the outstanding mechanical works.
Common problems include:
- Incomplete or incorrectly installed ductwork and refrigerant pipework.
- Ventilation systems that do not align with the approved mechanical design.
- Incorrect equipment supports, seismic restraints or service penetrations.
- Unresolved fire-stopping and coordination issues.
- Missing installation records, testing results or commissioning documentation.
- Delays to other trades waiting for mechanical works to be completed.
An unfinished installation is not necessarily defective. However, builders need a clear understanding of the existing work before appointing another contractor to complete it.
How to Recover an Incomplete HVAC Installation
Before work can continue, the builder needs to determine what has already been installed, what remains unfinished, and whether any existing work needs correction. If construction has progressed, access to equipment and services may also be limited, making some repairs more difficult.
The following steps provide a practical starting point.
1. Check What the Previous Contractor Actually Installed
The mechanical drawings may not reflect what is on site. The previous contractor may have rerouted ductwork, relocated equipment, or left sections of pipework unfinished. Compare the drawings with the installation and check whether the consultant approved any changes.
2. Inspect and Document Existing Works
A technical assessment should identify completed installations, outstanding works, visible defects and areas requiring further investigation.
This may involve reviewing ductwork, ventilation systems, equipment supports, refrigerant pipework and mechanical plant.
For an example of how PSB Air investigates and corrects existing installation issues, see PSB Air’s Ausgrid Ourimbah VRF Retrofit and System Compliance Upgrade, which involved rectifying non-compliant refrigerant pipework and ventilation control issues.
3. Confirm Design and Compliance Requirements
Compliance requirements depend on the project and systems involved, and should be assessed against the applicable National Construction Code (NCC) provisions, referenced standards, approved design and consultant requirements.
Where modifications are needed, the appointed engineering consultant may need to review and approve revised designs before work continues.
4. Establish the Remaining Scope and Responsibilities
Before rectification begins, the builder and incoming contractor should agree on what work remains, which defects require correction, and what can be retained.
Before work begins, the builder and incoming contractor should agree on which defects need fixing, whether any design changes are required and what work the new contractor will be responsible for. This helps avoid disputes over problems left by the previous contractor.
5. Develop a Coordinated Rectification Programme
Mechanical rectification often takes place while other construction activities are progressing.
Prioritising works that affect service penetrations, ceiling closures, rooftop installations or other trades can help reduce unnecessary disruption.
The recovery programme should account for available site access, construction sequencing and any outstanding consultant approvals.
6. Complete Testing, Commissioning and Handover
Once the installation is complete, inspect, test, and commission relevant systems against the approved design and project requirements.
Provide commissioning records, updated drawings, and applicable compliance documentation as required for project handover.
Managing HVAC Compliance and Coordination During Construction
Recovering an installation becomes more challenging once construction is underway. Ceilings may be partially completed, risers occupied by other services and mechanical equipment difficult to access. Changes to ductwork, service penetrations, or equipment locations can affect other trades, so coordination with the builder, engineering consultant, and relevant contractors is essential.
Carrington Road: Recovering a Challenging Residential HVAC Project
PSB Air encountered these challenges at the Carrington Road Residential Apartments development in Coogee, Sydney.
Engaged by JV Projects, PSB Air took over the mechanical services package after the original contractor left the project with incomplete works, construction defects and significant coordination issues.
The multi-storey development comprised more than twenty apartments, with mechanical services including Fujitsu VRF air conditioning, rooftop plant, basement ventilation, kitchen make-up air and exhaust systems.
The challenges extended beyond completing the outstanding installation. Hundreds of service penetrations required review and coordination, along with rectification of ductwork, equipment supports, seismic restraints, and fire-rated installations.
With construction already progressing, these works required extensive coordination with JV Projects and engineering consultant Seed Engineers.
PSB Air redesigned sections of the mechanical services, rectified inherited installation defects and completed the remaining works, including testing and commissioning.
The project shows how technical assessment, practical problem-solving, and close coordination can recover a challenging mechanical services installation and bring a development to completion.
It also highlights the coordination required to deliver complex HVAC systems for multi-storey residential developments.
What Should Builders Look for in a Replacement Mechanical Contractor?
Appointing a replacement mechanical contractor involves more than finding a business available to complete the outstanding work.
Builders should consider whether the contractor has the experience and technical capability to assess an existing installation and manage the challenges associated with inherited works.
Important considerations include:
- Experience with incomplete installations: Has the contractor previously managed partially completed or defective mechanical services projects?
- Technical assessment and reporting: Can they identify defects, outstanding works and potential design issues?
- Design and trade coordination: Can they work effectively with engineering consultants, builders and other trades?
- Clear scope and responsibilities: Does their proposal identify assumptions, exclusions and responsibility for existing defects?
- Testing and handover: Can they explain how completed systems will be tested, commissioned and documented?
Setting these expectations early can reduce misunderstandings and clarify the work required to complete the project.
Getting Your Mechanical Services Project Back on Track
An incomplete HVAC installation can create significant challenges, particularly when construction is already well advanced. Understanding the condition of the existing work, clarifying the remaining scope and coordinating rectification with other trades are essential to progressing towards completion.
PSB Air provides HVAC installation services for new residential and commercial buildings across Sydney, working with builders, developers and consultants on complex mechanical services projects.
Dealing with an incomplete mechanical services installation? Contact PSB Air to discuss a potential project takeover, including the current construction stage, outstanding works, and any known installation issues. Having current drawings and project timing information available can help with the initial discussion.
Frequently Asked Questions
Can a new HVAC contractor take over work started by another contractor?
Yes, but the incoming contractor will need to inspect the existing installation before agreeing to complete the work. They should also have the licences and experience required for the work involved. Agree on responsibility for defects left by the previous contractor separately, including what the new contractor is expected to test or certify.
Does an unfinished HVAC installation always need to be replaced?
Not necessarily. Ductwork, pipework, and equipment installed correctly may be suitable to keep. If parts of the system don’t match the approved design or were installed incorrectly, those sections may need repair or replacement.
Who is responsible for defects left by the previous mechanical contractor?
That depends on the original building contract and the circumstances surrounding the defects. A replacement contractor isn’t automatically responsible for fixing problems they didn’t create. The builder should establish who will pay for rectification and what the new contractor has agreed to take responsibility for.
Can an HVAC system be redesigned after construction has started?
Yes, although changes can become difficult once other trades have installed their services. For example, moving ductwork or mechanical equipment may affect electrical installations, ceiling heights, or available space in service risers. The engineering consultant may need to approve the revised design before work continues.
What documentation should a builder request from a replacement mechanical contractor?
Builders should receive updated drawings showing what was actually installed, along with records of any approved design changes. They should also confirm what inspection reports, commissioning results and compliance documents the contractor will provide at handover.
What can delay the recovery of an unfinished mechanical services project?
Access is often a problem when ceilings have already been installed, or service risers are crowded. Missing drawings, unresolved defects, or work another trade needs to complete can also hold things up. Identifying these issues before restarting the installation gives the builder a clearer picture of what is involved.
