TCCC
The Construction Contracts Co.
Subcontract Review
Australia
Trades / Mechanical and HVAC

Mechanical and HVAC subcontracts: the risks and what to negotiate

Mechanical and air conditioning packages carry design responsibility, long-lead plant and a commissioning phase at the very end of the job, which is where programme pressure lands hardest. The money risks sit in design liability, plant supply and completion defined by the whole building's commissioning.

AI risk report, not legal advice. The scanner gives general information about the risks in a document. It is not a lawyer, does not know your circumstances, and can be wrong. For decisions with legal consequences, get advice from a construction lawyer.

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Where mechanical and air conditioning subcontractors lose money

Design and fitness-for-purpose obligations

Design and construct mechanical packages often carry a fitness-for-purpose warranty that goes beyond reasonable skill and care, and that kind of risk is usually difficult to insure. Read whether you are warranting performance outcomes or just your design.

Plant lead times

Chillers, air handling units and controls can have long lead times. Without an extension of time for supply delays outside your control, a factory delay becomes your liquidated damages.

Commissioning at the end of the programme

Commissioning needs power, finished ceilings and controls integration from others. If your completion depends on whole-building commissioning, you carry everyone else's delay.

Long defects and seasonal testing

Seasonal commissioning can push final testing out a year. Check how that interacts with your retention release and defects period so money isn't held twice.

Three things to push for in your departures schedule

  • Design warranty limited to reasonable skill and care, not fitness for purpose
  • Extension of time for plant supply delays outside your control
  • Completion of your works defined by your own scope and tests

The free scanner finds these clauses in your actual contract in about two minutes and writes the departures schedule for you.

What the Index says

Live figures from the Australian Subcontract Index, 90 real subcontracts. The Index holds no mechanical and hvac contracts so far, under the 10-contract threshold, so these are national figures across all trades. Nothing under 10 contracts is ever shown.

100%have time bars that kill the claim entirely (66 of 66, all trades)
97%let the builder set off without notice (75 of 77, all trades)
78%have liquidated damages with no cap (31 of 40, all trades)
25 daysmedian payment terms (n=75, all trades)
5%median retention (n=65, all trades)
5 daysmedian notice window for variations (n=60, all trades)
See the full live Index →

Mechanical and HVAC subcontracts by state

Queensland →Payment capped at 25 business days; payment schedule due in 15.
New South Wales →Payment capped at 20 business days; payment schedule due in 10.
Victoria →Payment capped at 20 business days; payment schedule due in 10.
Western Australia →Payment capped at 25 business days; payment schedule due in 15.
South Australia →Payment schedule due within 15 business days of your claim.
Tasmania →Payment schedule due within 10 business days of your claim.
Australian Capital Territory →Payment schedule due within 10 business days of your claim.
Northern Territory →No payment schedule step: a dispute arises when a claim is rejected or unpaid, then 90 days to apply.

Mechanical and HVAC subcontracts: common questions

What is the biggest risk in a design and construct mechanical subcontract?

Usually the design warranty. A fitness-for-purpose obligation makes you responsible for the system achieving an outcome even where you used proper skill and care, and that risk is usually difficult to insure. Push for a reasonable skill and care standard.

Do mechanical and air conditioning subcontractors have payment rights that override the contract?

Yes. Every state and territory has a Security of Payment Act that lets you make a payment claim and get to adjudication quickly, and several states cap how long payment terms can be. The state pages below set out each one.

Is the scanner free?

Yes. No account, no card. Upload the subcontract and the full report appears in about two minutes. General information, not legal advice.

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