Key takeaways
- Gas pipework must be disconnected, capped and tested by a licensed gasfitter, and the builder coordinates the job rather than doing the gas work personally.
- A written survey of the appliances, pipe runs and flue penetrations before any disconnection prevents surprises inside walls and ceiling spaces.
- Any pipework left in place must be capped, labelled, tested and recorded in a way the owner can understand and a future trade can find.
- Electric replacements need the switchboard capacity checked and the order of works agreed, so that gas is made safe before a new appliance is connected.
- Gas decommissioning should be priced as a separate item with the scope confirmed in writing, because the cost of a poor job appears years later when the house changes hands.
Removing gas from an existing home is one of the quieter jobs in a renovation, and one of the easiest to get wrong. The cooktop comes out, the hot water unit is replaced with a heat pump, the ducted heater is retired and the owner asks for the meter to be removed. Each of those tasks looks simple on the schedule, but each one touches a live gas system, a flue, a set of penetrations and a set of responsibilities that often sit between three or four trades. The result is that gas is frequently left half-removed, with pipes in the walls and no one who is sure whether they are safe.
The interest in removing gas is growing, and so is the number of renovations that take it out. Owners want to remove an appliance that they no longer use, to reduce the bills or to move to electric appliances. The builder is usually the person the owner expects to manage the change, even though gas work is licensed and must be carried out by a qualified gasfitter. That gap between who manages the job and who does the gas work is where most of the problems start.
This article sets out the process for decommissioning gas services in an existing house during a renovation or a rebuild. It is not about all-electric new builds, which raise different questions about the design of the home. It is about the practical sequence on a live site, the responsibilities that sit with the builder and the gasfitter, and the commercial risks that come with leaving gas behind.
Who is responsible for what when gas comes out
Gas work in NSW is licensed work, and the disconnection, capping, removal and testing of gas pipework must be carried out by a licensed gasfitter. The builder’s role is to coordinate the job, make sure the gas work is scheduled and completed before the trades that depend on it arrive, and keep the records of what was done. The builder should not disconnect or cut gas pipework personally, however competent they are with other trades, because the licence requirement is specific and the consequences of a gas leak are serious.
The owner is responsible for the decision to remove the appliance or the service, and they need to be told in writing what the gasfitter will do, what will be left in place and what the costs are. Ask the gasfitter to confirm the scope in writing, including whether the gas meter will be removed or left in place, because a meter that remains connected to the network carries different obligations from one that is decommissioned. The network operator or the energy retailer may need to be advised before any meter is removed or disconnected, and that is a question for the gasfitter and the owner to resolve before the date is set.
The tax office’s taxable payments reporting regime applies to some building and construction businesses, and the payments made to a gasfitter or other subcontractor may be reportable depending on the structure of the business. The business should check whether its payments fall within that regime, and keep the invoices and subcontractor details in the job file so that the answer can be given quickly if it is needed.
The decommissioning sequence
- 1Survey the houseWalk the house and roof space with the gasfitter and record every appliance, pipe run and flue.
- 2Test for other hazardsAssess suspect materials such as flue linings before anything is disturbed.
- 3Isolate and capIsolate the supply at the point the gasfitter specifies, then cap and test each pipe.
- 4Remove and make goodRemove appliances and flues in the order directed, and seal penetrations only after sign-off.
- 5Record and hand overGive the owner and the job file a written record of what was removed, what was left and where.
Surveying the house before anything is disconnected
Start with a survey of what is actually there. Old homes often have gas lines that were added in stages, appliances that were replaced without the pipework being changed, and flues that run through the roof space in ways that do not match the drawings. Walk the house and the roof space with the gasfitter before the job is priced, and make a list of every appliance, every pipe run that you can see and every flue penetration. Check the meter location and the isolation valves, and note whether the pipework is exposed or buried in the wall or the floor.
The survey should also look for hazards that have nothing to do with gas. Older homes can contain asbestos in flue pipes, wall sheeting, backing boards and the sealant around old fittings. Asbestos is not a gas problem, but it is discovered in the same places that gas work is carried out, and the rule is the same: do not disturb suspect material until it has been tested and, where necessary, removed by a licensed removalist. A builder who is removing a flue on the assumption that it is harmless may find a serious hazard hiding in the lining.
Record the survey with photographs and a sketch. Mark the locations of the pipes, the appliances and the flue penetrations on a plan, and keep the plan with the job file. A survey that is recorded at the start makes the end of the job much easier to check, and it is the document that will be asked for if a problem appears later.
Isolating, capping and removing the gas service
The gas supply should be isolated at the point the gasfitter specifies, usually the meter or a main isolation valve, and the isolation should be tested before anyone starts work on the pipes. Do not rely on a closed appliance valve to stop the gas. Appliance valves can leak, and a leak that is not stopped at the source can fill a room or a roof space. The gasfitter should make the isolation safe and document it before the appliances are removed.
Each pipe that is being removed should be disconnected at a point the gasfitter selects and capped in a way that will hold under the pressure of the system. Pipes that are being left in the walls or floors should be capped, labelled and tested. A pipe that is simply cut and left open in a wall cavity is a hazard for the next trade and for the owner, and it is also a fault that the gasfitter cannot certify. Ask for a written record of where each cap sits and how each pipe was tested, and keep it with the job file.
Where a flue is being removed, the penetrations through the roof and the walls need to be made good in a way that keeps the weather out and the building structure sound. The penetrations should be checked for any residual gas or combustion gas before they are sealed, and the roofer or the carpenter should not seal them until the gasfitter has signed off the work. Remove the appliance and the flue in the order the gasfitter directs, and keep the old appliances labelled for disposal.
Lead in. The mistake that costs the most is leaving gas pipework capped by nobody and labelled by nobody, buried in a wall that is then lined. The next trade, the owner or a future renovator will find it without warning, and the only record of its position is a memory on a site that is long gone.
What is left behind, and how to make it safe
Many gas decommissioning jobs leave something behind. A pipe that is still needed for a second appliance, a meter that the owner has chosen to keep, or a line that runs to an outdoor point are all examples. Each one needs to be recorded and made safe in a way that the owner understands, because an owner who does not know what is left in the walls cannot manage it later.
Make the record specific. A note that says there is gas pipework in the wall behind the kitchen is not enough. The record should say where the pipe runs, what it is capped to, how it was tested and who did the work. Give the owner a copy, and keep a copy in the job file. The owner is the person who will be asked about the house when it is sold, and the record is what allows the question to be answered.
Ventilation needs attention when the gas load is reduced but not removed. Remaining appliances still need the air they were designed for, and removing a flue can change the way the house breathes. Ask the gasfitter to confirm whether any remaining appliance has adequate ventilation, and whether a new appliance will need a different arrangement. Ventilation advice for any remaining appliance should come from the gasfitter in writing, and it should be filed with the rest of the job records.
Replacing the gas with electric appliances
When gas comes out, the owner often wants electric appliances to go in. That brings the electrical supply into the picture, and the electrical capacity of the home may need to be assessed before the new appliances are installed. A cooktop, a heat pump hot water unit and a heating system can each draw a significant load, and the switchboard may not be able to carry them all at once. Check the capacity with the electrician before the appliances are ordered, not after the gas has been removed and the new unit is sitting in the garage. The article on electrical load management in electrified homes covers how that capacity check is approached.
The sequence matters. Replacing an appliance before the gas is decommissioned can leave a gas line live next to a new electrical installation, and that is a combination that causes accidents. Agree the order of works with the owner, the gasfitter and the electrician, and put it on the program. The gas comes out first, is made safe, is signed off and only then is the new appliance installed.
The wider question of what an electrified home needs is covered in the guide to all-electric homes for builders. For a renovation, the practical issues are the switchboard, the cabling route to the new appliance and the space that the new unit needs, and each of them should be settled before the gas comes out.
Before the new electric appliance goes in
- The gasfitter has issued written confirmation that the gas is isolated, capped and tested.
- Every pipe left in place is labelled and recorded on the plan.
- Any suspect material has been assessed, and removed if necessary, before work continues.
- The switchboard capacity has been checked by the electrician for the new appliances.
- The owner has accepted in writing what is being left behind.
- The job file holds the survey, the certificates and the photographs.
Worked example: a renovation of an older house
Consider a builder in a Sydney suburb who was renovating an older brick house. The owner wanted the kitchen gas cooktop, the ducted gas heater and the gas hot water unit removed, and the new kitchen to be fully electric. The builder’s quote included the removal of the appliances and the new electrical work, but the gas decommissioning was left as an allowance on the schedule, to be confirmed later.
When the gasfitter arrived, the survey found that the gas line to the heater ran through the ceiling space and had been buried in a wall that was going to be lined. There was also a flue that had been lined with a board the builder suspected might contain asbestos. The builder stopped the work, called a qualified asbestos assessor, and asked the gasfitter to isolate and cap the line in the ceiling and label it. The owner was told that the job would take longer, and the cost of the assessment and the additional gas work was agreed in writing before the work proceeded.
The job finished a few weeks later than planned. The owner had a clear written record of what had been removed, what was left and where, and the wall that was going to be lined was checked and signed off before the plasterer arrived. None of the decisions was dramatic. Each was the ordinary procedure, applied before the pressure to skip it arrived.
The commercial reality of leaving gas behind
Gas decommissioning is often treated as an extra on a renovation, and it is priced as a minor line on the quote. That is a commercial mistake. The gasfitter’s time, the testing, the making good, the asbestos assessment if one is needed and the records all cost money, and the builder who has not priced them is carrying the cost. Price the gas work as a separate item, with the scope confirmed in writing, and make it clear to the owner what is included and what is not.
The cost of a poor job does not show up on the day. A pipe left uncapped in a wall, a label that was not made, or a flue penetration that was sealed before it was checked can surface years later, when the house is sold, when a new owner renovates or when a leak appears. At that point the question is always who did the work and what was recorded, and the builder who kept the records is in a much stronger position than the one who relied on memory.
Keep the job file complete. The survey, the scope, the gasfitter’s certificate, the record of each cap and label, the asbestos assessment where one was needed, and the owner’s written acceptance of what was left behind should all sit in one place. That file is the builder’s evidence that the work was done properly, and it is the first thing a professional who inherits the house will want to see.
Where the work fits in your CPD and your business
Gas decommissioning sits between several trades and several licences, and the builder who understands where the responsibilities split will avoid most of the disputes. The same is true of the electrical work that follows and the asbestos question that sometimes arises. Build the sequence into your standard renovation process, so that the gas decision is made at the start of the job rather than at the end.
If you are keeping your licence current, the PointCPD guide to NSW builder CPD explains the renewal requirement in plain terms. The PointCPD course catalogue lists the NSW builder CPD courses we offer, and the sustainability topic area is a practical place to look when electrification and renovation work is becoming a larger part of the business.
Questions builders ask
Can a builder disconnect a gas appliance during a renovation?
Gas work in NSW is licensed work, so the disconnection, capping and removal of gas pipework must be done by a licensed gasfitter. The builder should coordinate the job, make sure the gasfitter attends at the right time and keep the records of what was done.
What should happen to gas pipework that is left in a wall?
Any pipework left in place should be capped, labelled, tested and recorded. The record should say where the pipe runs and how it was made safe, and a copy should go to the owner and into the job file.
Could an old flue contain asbestos?
Yes. Older homes can contain asbestos in flue pipes, wall sheeting and backing boards, so suspect material should not be disturbed until it has been assessed and, where needed, removed by a licensed removalist. Gas work and asbestos work should be sequenced with that in mind.
Do I need to check the electrical supply before replacing gas appliances?
Yes. Replacement electric appliances such as cooktops and heat pump hot water units can draw a significant load, so the switchboard capacity should be checked with the electrician before the appliances are ordered. The gas should be made safe before the new appliance is connected.
Who should be told before a gas meter is removed?
The network operator or the energy retailer may need to be advised before a meter is removed or disconnected. Ask the gasfitter to confirm what notice is required, and agree the date with the owner once the notice has been given.
How should gas decommissioning be priced on a renovation quote?
Price it as a separate item, with the scope confirmed in writing and the gasfitter’s time, testing, making good, any asbestos assessment and the records all included. Leaving it as a minor allowance on the quote is how builders end up carrying costs they did not plan for.
Sources
- Building and construction services (TPAR) · Australian Taxation Office
- Continuing professional development for builders and swimming pool builders · NSW Government
- General building work licensing · NSW Government
Published 13 October 2026. General information for builders, not legal, financial or engineering advice for a specific job. Check current requirements with the relevant regulator or standard before relying on them.
