Appliances connected, tested and certified. And on a property with rooms below the entry level, a proper answer about where a leak would actually collect.
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Most gas safety advice is written for a single-level house where it does not much matter which direction a leak travels. On a property with rooms below the entry level it matters a great deal.
Natural gas, the kind that arrives through a meter from the street, is lighter than air. A leak rises and disperses upward, which is why high-level ventilation is what deals with it.
LPG, the kind that comes in bottles or a tank on the property, is heavier than air. It sinks. It finds the lowest point available and stays there: a lower-ground room, a cellar, a plant space, a boat shed, a stairwell that goes down rather than up.
So a leak that would dissipate harmlessly in a flat-plan house can pool in a low space here and remain. That is why we confirm which gas a property has before giving any advice at all, and why a room that seems well ventilated at head height can still be wrong for LPG.
Go up and out, not down. Where it collects depends on which gas it is, and down is the wrong direction for LPG.
Open up, get everybody outside, touch nothing electrical on the way, and ring from outdoors. That sequence does not change with the type of gas.
Turn the supply off if you can reach it safely: the meter for natural gas, the cylinder valve for LPG. The cylinder valve is usually the easier of the two.
A licensed gas fitter answers when you ring us, and where the network's emergency crew is the right first call we will say so rather than take a booking.
Natural gas is lighter than air and disperses upward. LPG is heavier than air and does the opposite: it sinks and pools at the lowest point available to it.
That single physical difference changes where a leak accumulates, what ventilation is needed, and which parts of a building carry risk.
It is the reason this page exists, and it matters most on properties with rooms below ground level.
Mains gas arrives through a meter connected to the street. LPG comes in cylinders standing beside the building or in a tank.
It takes one look and it is worth doing before any conversation about appliances or ventilation, because the advice differs.
Some properties here have both: mains to the house and a cylinder for a barbecue or an outdoor appliance. In that case the appliance in question decides which applies.
A lower-ground room, a cellar, a plant space or a downward stairwell is exactly where heavier-than-air gas collects, and on harbourside blocks built into a slope those spaces are common.
A boat shed at the bottom of a property is the same situation. So is an under-house storage area that has been enclosed over the years.
None of that makes LPG unsuitable. It makes the assessment of the space a real part of the job rather than a formality.
Low-level ventilation is what matters for LPG, because that is where it accumulates. High-level ventilation is what disperses natural gas.
So ventilation designed for one is not automatically adequate for the other, and a property that has changed fuel at some point is worth looking at on that basis.
It is a specified requirement rather than a judgement call, which is why it can be assessed rather than guessed at.
Whether an LPG appliance suits a particular low space depends on that space more than on the appliance: its volume, its ventilation, and where the air can actually go.
That is a different conversation from the usual one about clearances and flue positions, and it is the one that matters here.
It is also why we would rather look at the room than answer the question over the phone.
Upright, outdoors, in ventilated space, away from ignition sources and away from drains and openings that lead to lower levels.
Under a deck, in a closed garage, or beside a stairwell going down is the arrangement to avoid, and it is a common one on sloping blocks where space is tight.
Cylinders also expire. There is a test date stamped on the collar, and a filler will refuse one past it, which is generally how people find out.
Adding an appliance is a calculation against total demand rather than a connection, and on LPG the regulator and the cylinder capacity come into it as well as the pipe.
The input rating on the appliance plate is the number the calculation runs on, and a photograph of it is enough to get started.
Where the sums do not work, appliances starve each other, and a burner that drops off whenever something else runs is nearly always this.
Pipe sized for the run and the load, tested to pressure, appliances installed to the manufacturer's instructions with the required clearances, flueing that discharges where it should, and ventilation suited to the gas, the appliance and the space.
That last item is the one this page is about, and it is the one most often got wrong on a property with rooms below ground.
None of it is visible once the job is finished, which is exactly why the certificate matters.
Legally required, issued by the licensed gasfitter, and the only durable proof that the work was done by somebody entitled to do it and tested afterwards.
Keep it with the property papers. It is what an insurer asks for after an incident and what a conveyancer asks for at sale.
It applies equally on LPG. Bottled supply is not a lesser category of gas work and it is not exempt from anything.
Agreed before we start. These are indicative 2026 ranges. The Certificate of Compliance is included on every gas job and is never charged as an extra.
Any hour. Isolated and made safe first, then diagnosed properly.
For a lower-ground room or plant space, matched to the gas actually in use.
Cooktop, oven, heater or bayonet onto an existing point, tested and certified.
Priced on the route and what it has to pass through.
On every gas job. Legally required, and never charged for here.
Mains or LPG. It changes the safety advice and it changes where a leak would be.
Supply isolated first on any suspected leak, then pressure tested to find where it is actually escaping.
For LPG in any low space, at floor level rather than at head height.
Tested again on completion and your Certificate of Compliance issued on the spot.
Get everyone out and upward rather than down, avoid anything that could spark, and ring us from outside. A licensed gas fitter answers at any hour.
Call 1300 381 569Stop reading and act. Do not touch a light switch, a power point or anything that could spark, and do not use a phone inside the building. Open doors and windows on the way out, turn the gas off at the meter if you can safely reach it, get everyone outside, and ring from outdoors. On a property with lower levels, go UP and out rather than down, because where the gas collects depends on which gas it is. We answer 24 hours.
Because they behave in opposite directions, and on a property with rooms below the entry level that matters a great deal. Natural gas is lighter than air, so a leak rises and disperses upward. LPG is heavier than air, so it sinks and collects at the lowest point it can reach: a lower-ground room, a cellar, a plant space, a boat shed, a stairwell that goes down rather than up. A leak that would dissipate harmlessly in a single-level house can pool in a low space and stay there.
Mains gas is natural gas and arrives through a meter connected to the street. LPG comes in cylinders or a tank on the property, and there is no street connection. If you are refilling or swapping bottles, it is LPG. If you have never thought about where it comes from and there is a meter at the boundary, it is almost certainly natural gas. We confirm it as a matter of course, because the safety advice differs.
That the ventilation has to suit the gas. Low-level ventilation matters for LPG because that is where it accumulates, and a room that appears well ventilated at head height can still hold LPG at floor level. High-level ventilation is what disperses natural gas. This is a genuine design question rather than a formality, and on a property with lower-ground rooms it deserves proper attention rather than an assumption.
It depends entirely on the room and how it is ventilated, and it is not a decision to make from a catalogue. The combination worth being careful about is LPG plus a space with no low-level ventilation and no route out at floor level. We assess the actual room rather than giving a general answer, because the general answer is neither yes nor no.
Always, on every gas job, without asking. A Certificate of Compliance is legally required for gas work in NSW and it records what was done, that it was tested, and under whose licence. Keep it with the house papers, because insurers ask for it and so does anyone buying the property.
A leak test and make-safe is $200 to $450. Connecting an appliance to an existing point is $250 to $550. A new gas point or run is $450 to $1,200 depending on the route. A ventilation assessment for a low-level room is $180 to $350. The compliance certificate is included on every gas job.
Tell us whether it is mains gas or LPG, and whether the room involved sits below the entry level. Those two answers change the advice entirely.
Which gas confirmed first, ventilation assessed where it matters, and a Certificate of Compliance before we leave.
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