Ductwork near you

A duct quote that says only replace ductwork is not a quote you can compare. The distribution system is an assembly of distinct components, and installers make very different choices about each one, so ask which of these the price covers.

The insulation wrapped around a duct is not a comfort extra. A roof space in an Australian summer runs far hotter than the air being pushed through the duct, so a poorly insulated run in January is a heat exchanger working against you — the air arrives at the bedroom warmer than it left the unit, and the system runs longer to make up the difference. In the June to August heating season the same physics runs in reverse and warm air gives its heat up to a cold roof space.

Part 13.7 of the ABCB Housing Provisions puts numbers on it. For ductwork serving heating only or cooling only, the minimum material R-value is 1.0 in climate zones 1 to 7 and 1.5 in climate zone 8, with fittings at 0.4. Where a single system provides both heating and refrigerated cooling, the minimum rises to 1.5 in climate zones 1, 3, 4, 6 and 7, and stays at 1.0 in climate zones 2 and 5. The Australian Building Codes Board's climate zone map is what tells you which of those figures applies to your postcode.

Sealing is the other half and gets less attention than it deserves. The Housing Provisions require ductwork to be sealed against air loss by closing all openings, joints and seams, to the Class C seal of the relevant Australian Standards, with flexible ductwork sealed using a draw band in conjunction with a sealant or adhesive tape. Duct insulation must abut adjoining insulation to form a continuous barrier, and where ductwork is located outside the building it must be protected by an outer sleeve of protective sheeting, with adhesive tape not less than 48 millimetres wide creating an airtight and waterproof seal.

Licensing in Australia is done state by state, so the honest answer to who is allowed to install your ducts depends on your postcode. Queensland is the clearest case and a useful benchmark to hold other quotes against: the QBCC issues an air handling duct installation licence whose stated scope is installing ductwork and enclosures for air conditioning, air handling and mechanical ventilation systems, and a mechanical services air-conditioning and refrigeration occupational licence covering constructing, installing, replacing, repairing, altering, maintaining, testing or commissioning air-conditioning, air handling systems and refrigeration for a building.

The connections at either end are licensed regardless of where you live. If the ducts are fed by a gas heater, the gas side is gasfitting: Queensland requires a licence or authorisation before you do any gas work at all, regardless of whether the work is residential, commercial or industrial, with gas work defined to include installing, removing, altering, repairing, servicing, testing and certifying the gas system of a gas device. In Victoria the plumbing regulator administers licensing and registration for plumbers and gasfitters, and every registered and licensed practitioner carries a photo identification card listing the type of work they may do, with the registered classes printed on the back.

The electrical supply to the indoor unit and its controls is separate again. New South Wales requires an electrical licence before undertaking any electrical wiring work, regardless of the cost or type of work, and electricians must submit certificates proving compliance. In Victoria a certificate of electrical safety is a legal document recording the work performed, and for non-prescribed work — the category that expressly includes air conditioning — the contractor must give you a copy within thirty days. Ask at quoting time which trades are attending and what each one is licensed for.

A credible job starts with somebody physically in the roof space with a camera, not with a price over the phone. The survey should establish where the plenum sits, how each run is routed, what condition the insulation is in, where runs are crushed or disconnected, whether the return air path is adequate for the equipment, and — a genuine constraint in Australian homes — whether the roof space can be safely traversed at all. Ask for the photographs. A duct contractor who will not show you what they found is asking you to buy something you are structurally unable to inspect.

Design comes next, and this is where money is either well or badly spent. Run lengths are shortened where the building allows, trunk runs are sized for the air the equipment is rated to move, branch runs are balanced so the far bedroom is not starved by the near one, outlet positions are chosen for the shape of each room, and the zoning is set out to match how the household actually lives rather than how the floor plan is drawn. Replacing like for like simply reproduces whatever compromise the original installer made.

On installation day, the old duct comes out rather than being left in place, new runs are pulled taut and strapped up clear of the ceiling insulation, joints are sealed and the insulation is lapped to form the continuous barrier the code requires, and outlets are cut and fitted. Commissioning is the part to insist on: the system is run, airflow is checked at each outlet, zones are proved to open and close, and anything still weak is balanced before the crew leaves. Get the result in writing alongside the photographs.

Book duct work for spring or autumn, and treat December as a deadline rather than a starting point. Australian cooling demand peaks from December through February, and by the first serious heatwave the contractors covering your postcode are booked out. A house discovering in January that half its outlets are weak is in the worst possible position to compare quotes carefully.

There is a physical reason on top of the scheduling one. A roof space in a Sydney, Perth or Brisbane summer becomes dangerously hot within a couple of hours of sunrise, which compresses the safe working window to the early morning and makes careful work in the tight sections near the eaves genuinely difficult. The same roof space in September or April is merely uncomfortable, and the quality of what gets done in it is noticeably better.

If your system is mainly for heating, use the same logic shifted: the heating season is June to August, so autumn is the window. Sustainability Victoria's practical advice for an older ducted heating system is to have the ductwork checked when the heater is serviced, which pairs the two visits sensibly and means the ducts get looked at by someone already up there.

Ductwork disputes are hard to settle because the evidence is above a ceiling. That is an argument for collecting the evidence while the roof space is open. Ask for before and after photographs of the plenum, the trunk runs and the branch take-offs, a note of the R-value of the duct actually installed, and the commissioning record showing airflow was checked at the outlets. Those three things convert a vague complaint about a cold back bedroom into something a contractor can be held to.

Keep the certificates that belong to the connected trades as well: the certificate of electrical safety or the state equivalent for any electrical work, and the gas compliance certificate where a gas heater was connected or reconnected. Never accept a discount in exchange for leaving certification off the job, because the certificate is the part that survives the handshake.

Finally, write down what the system is supposed to achieve before work starts — which rooms, in which zones, at what kind of temperature — and hold a meaningful part of the payment until the system has been demonstrated. A duct installation is one of the few home jobs where the difference between competent and careless is invisible on the day and obvious for the next fifteen years.

Underneath the paperwork sit rights you cannot sign away. The ACCC states that consumer guarantees are automatic and cannot be taken away, and that service providers must carry out all services using an acceptable level of care and skill. Ductwork gives that unusually sharp edges, because the ACCC's test for a major problem with a service includes one that cannot achieve a specific result the consumer told the seller about and cannot easily be fixed within a reasonable time — which is precisely the situation where a system installed to condition named rooms does not condition them. Where a problem is major it is you, not the business, who chooses the remedy: cancelling the contract for a refund, which may not be a full one because a reasonable amount is payable for work properly done, or keeping the contract at a lower price that takes the problem into account. Where the problem is minor, the business must fix it for free.