Subfloor Ventilation in Newcastle and Lake Macquarie
Subfloor ventilation moves air through the space under a suspended floor, or draws the damp air out of it, so moisture rising from the ground has somewhere to go. That keeps the timber drier and makes the house less attractive to termites and other pests. Benefit Pest Management assesses and installs subfloor ventilation across Newcastle, Lake Macquarie and the Hunter. Our head technician holds pest management technician licence 5083379, issued by the New South Wales EPA.
We get back to every enquiry within one business day.
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What subfloor ventilation does
Most people never go under their house, which is exactly why a damp subfloor can sit there a long time before anyone finds out. Damp doesn’t announce itself. The first sign is usually a musty smell, mould, rotting timber or termites.
The subfloor is the space between the ground and the underside of a suspended floor. Moisture comes up out of the soil into that space all the time. With air moving through, it gets carried away. Without it, the air underneath stays damp, and the timber frame that holds the floor up sits in it, along with the floorboards on top.
Subfloor ventilation is what keeps that air moving. The National Construction Code calls it cross ventilation of the subfloor space, and it gives the reason in plain terms. Ground moisture makes a damp environment that encourages timber rot, fungus and termites. Airflow reduces the water vapour that does the damage.
One of oursDucting run between the piers under a house, towards a wall vent.
Damp subfloor, happy termites
Subterranean termites have to stay damp or they dry out, so a wet subfloor is about as good as it gets for them. Down there they get moisture and timber close to the soil. They also get somewhere quiet that nobody checks.
That’s why a subfloor with no real airflow sits on the list of conditions we look for on every termite inspection. Drying it out doesn’t treat termites that are already there. What it does is make the house less attractive to them in the first place, and it can help a treatment last longer. The wider picture is on our termite control page.
Standard home insurance policies don’t cover termite damage, so a damp subfloor is better fixed before termites find it. Where the damp is coming from a leaking pipe or a downpipe rather than a lack of air, the report says so and names the trade to call.
One of oursDark, damp soil between the piers under a house.
Mould, smell and the floor above it
Mould needs moisture and still air, and a closed-in subfloor offers both. NSW Health lists the places mould grows in a damp house with poor ventilation: walls, ceilings, carpets, insulation and timber. Its fact sheet on mould also notes that poor subfloor ventilation or moisture under the floor makes rising damp in brick walls worse.
The fact sheet says mould is likely to come back unless the cause is dealt with. Cleaning gets rid of the mould you can see. Ventilating the subfloor moves out the damp air that keeps feeding it.
Two simple checks are worth doing now. Make sure the vents and weep holes (the small gaps along the bottom of a brick wall) aren’t covered by garden beds, paving or a deck. Then look for anything stored up against them. NSW Health gives the same advice.
What affects subfloor ventilation cost
We don’t publish prices, for subfloor work or anything else, because every subfloor is different. What moves the price:
The size and height of the subfloor. A big house with a tall subfloor is a different job from a small house you can barely crawl under
How hard it is to get under. Low clearance, tight piers and no access hatch all add time
How many ventilation units and how much ducting it needs. That depends on the size of the space and how damp it is
Whether power has to be run. A fan needs a power point, and we don’t do electrical work, so the electrician we work alongside puts it in
You get a fixed price before anything starts. Sometimes the subfloor is fine as it is, and you’ll hear that too. Talk it over with us on 0467 561 548.
Fans, vents and which your house needs
There are two ways to move air through a subfloor. We fit ducted subfloor ventilation units: fans that move the air through ducting under the floor.
The other way is vents: openings in the external walls and in the internal subfloor walls that let air cross from one side of the house to the other. They rely on the breeze and on the difference in temperature and humidity between the subfloor and outside. The building code wants them spread evenly, placed near the corners and lined up through both layers of a double brick wall, with no dead air pockets left in between. Vents also get blocked over the years by an extension, a garden bed or a deck.
Fans do the moving when the breeze can’t. A mechanical system draws the damp air out of the subfloor and pulls drier air in. Fans make sense where vents can’t do it on their own: a low subfloor, a house where the breeze can’t reach the walls, or a space too big for air to cross to the middle.
Which your house needs depends on what’s under there: how damp the ground is, how the air moves now, and what’s stopping it. The first step can be as simple as clearing the vents the house already has.
Do you need subfloor ventilation?
If your house sits on piers or stumps over a crawl space, the subfloor needs airflow, and the question is whether it’s getting enough.
The way to find out is to have someone go under there. A termite inspection does that: the moisture meter and the thermal camera go under the floor with us on every one we do. A musty smell or damp timber down there tells us a lot as well. AS 3660.2, the Australian Standard for termite management in existing buildings, sets the gap between termite inspections at not more than twelve months, so if yours is due, that’s the easy time to check.
We’re the ones who crawl under there, so you don’t have to.
One of oursSuited up under a house, respirator on.
Subfloor work across Lake Macquarie and Newcastle
Lake Macquarie is Australia’s largest coastal lake, and Maitland sits on the Hunter River floodplain. Both put a lot of houses close to water. Where the ground under a house is excessively damp or floods often, the building code asks for more than the usual: extra ventilation, a moisture barrier laid over the ground, or subfloor timbers that can handle the damp.
Signs from inside the house
You don’t always have to go under the house to suspect a problem. These are worth a call:
A musty smell in the house, strongest near the floor
Mould on skirtings, the bottom of walls or the underside of carpet
Damp or flaking patches low on brick walls
Termite damage found anywhere in the house
Where we do this
We work from our base at Caves Beach across Newcastle, Lake Macquarie, the Hunter, Port Stephens and the Central Coast, with no call-out fee.
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FAQ
Common questions about subfloors
Does a subfloor need ventilation?
Yes, if the house has a suspended floor. Under the National Construction Code, a subfloor needs openings that let air cross it, because moisture from the ground otherwise builds up underneath.
Does a house on a slab need subfloor ventilation?
No. A slab sits directly on the ground, so there’s no space underneath to ventilate. Moisture around a slab is a drainage and garden bed question instead, and our integrated pest management page covers that side.
How do I stop dampness under the house?
Deal with the water first, then the air. Fix leaking pipes and downpipes, make sure the ground drains away from the house, and keep the vents and weep holes clear. If the subfloor is still damp after that, it needs more airflow than it’s getting.
What are the requirements for subfloor ventilation in Australia?
The National Construction Code covers it. In broad terms: openings in the external and internal subfloor walls, sized for how humid the area is, spread evenly and near the corners, with the space kept clear of building rubbish and plants. Very damp or flood-prone ground calls for more ventilation or other measures. A builder or certifier can tell you what applies to your house.
Will subfloor ventilation get rid of mould?
Not on its own. It deals with the damp the mould grows on. Mould you can already see still needs cleaning, and NSW Health’s fact sheet on mould explains how. Without the damp, mould has much less reason to come back.
Does subfloor ventilation stop termites?
No. It makes the house less attractive to them, which is worth doing, but it doesn’t treat a colony that’s already there. Once the fans are in, keep up your termite inspections.
Do you do the electrical work for subfloor fans?
No. We don’t do electrical work. We work alongside a licensed electrician, who puts in the power points for the fans.
Next step
A damp subfloor won't fix itself
We go under the floor with a moisture meter and tell you what’s causing the damp and what will fix it.
You can also tell us what you’ve noticed in the form.
We get back to every enquiry within one business day. A quote costs nothing, and neither does the advice.
