? What is
Sub Floor Ventilation?

Subfloor ventilation is installed in your subfloor space, removing moist air and enabling dry air to circulate beneath your floor. The system prevents problems associated with damp and mould in your home.

Top 6 Most Popular FAQ`s

Subfloor ventilation systems work by extracting damp air from your subfloor space.

This then allows dry air to enter the area under your floor.

By keeping the area under your floor dry, subfloor ventilation reduces problems associated with damp, and prevents mould, moisture and other undesirable elements from taking hold in your home.

Subfloor ventilation not only makes your property more comfortable and pleasant for those who will be spending time there, but it also makes the environment safer and healthier.

Damp and mould can damage the structure of your home, impacting its value and potentially rendering it unfit for habitation.

Pests, such as termites, are more likely to infest damp homes, bringing more structural issues, while mould growth and mould spores can cause breathing difficulties and exacerbate allergies.

The professional will begin by visiting your property and examining your subfloor space.

They will then ascertain where is the best location to send damp, stale air out of the subfloor space so fresh and dry air can enter.

Once the area has been surveyed and the exhaust points have been identified, installation can begin.

The team will install fans at strategic points beneath your floor, as well as ducts that are used to remove the humid air and achieve a dryer, cleaner environment in your home.

Vents through the foundation walls are also installed to provide a fresh air supply to the subfloor space.

Making sure that your building is well maintained, that there is adequate drainage around your building, and that your brickwork and insulation is not damaged is a good way to prevent moisture creeping into your subfloor area.

However, adverse weather and climatic conditions, as well as the general ageing of your property, can make this difficult.

Subfloor ventilation is an ideal way to reduce the build-up of moisture and to prevent moisture from entering the property in the future.

This, in turn, will eliminate the problems that excess moisture and humidity bring with them.

Your subfloor space should already be equipped with vents and other features that permit air to flow in and out of the space.

Adding more of these vents in strategic places may help with ventilation, but it may not be sufficient to achieve the ventilation you are looking for.

A subfloor ventilation system provides more effective ventilation because it uses fans to exhaust damp air and to keep fresh air circulating throughout the space.

Without this assistance, air can end up trapped in different areas of the subfloor space, leading to localised problems with mould and damp that can rapidly spread into other areas of the home.

Vents are installed on both sides or all sides of a building to create airflow.  The vents are installed below the joists.

Fans can be installed to drag clean fresh air under the floorboards similar to that in our diagram above. 

Subfloor Ventilation: An Effective Solution to Combat Subfloor Mould and Damp at Your Property

What is subfloor mould, and what are its causes?

We have all heard of mould, and we know that it is something very unpleasant. It’s ugly, it’s disgusting, and it can cause health problems within our home.

But what exactly is it?

To put it simply, mould is a kind of fungus.  We may see mould beginning to appear on food when it is spoiled and going off.

But what about in the home?

In order to grow, mould needs a moist, warm space where it is undisturbed. Unfortunately, because of Australia’s climate, our homes contain lots of moist, warm spaces that are ideal for mould to take root. In fact, even if we disturb mould growth with constant cleaning, it will simply keep on coming back until the root causes are dealt with.

When mould growth occurs beneath our floor space, this is known as subfloor mould.

The causes of subfloor mould


As mentioned, subfloor mould occurs when the conditions are right for mould to begin to grow. Why is this exactly?

  • Poor ventilation under the floor means that air becomes stale and damp.
  • Poor drainage around the property results in damp soil in the subfloor
  • Humid weather conditions lead to moisture build-up.
  • Mould spores take root in a place we cannot reach to clean.
  • Dampness in the soil beneath our home rises into our property.
  • Once mould begins to grow, it can be difficult to get rid of, and urgent measures need to be taken.


How does subfloor ventilation help to remove mould?


We’ve already touched on the three factors that help mould grow. These are warmth, moisture, and a place in which growth won’t be disturbed.

In your subfloor space, the mould has access to all three of these factors.

  • The air tends to be warm, especially in the summer.
  • In some parts of the country, the air may be extremely humid.
  • You cannot reach the mould to clean it.

Accessing the underfloor level to regularly clean away the mould is impractical. And, anyway, the mould will simply grow back again.

Reducing the temperature of the air is also not so feasible. It will be expensive to maintain a low temperature beneath your floor during the hotter months.

This leaves the moisture and humidity. This is where a subfloor ventilation system makes all the difference.

The subfloor ventilation system uses its system of fans, ducts, and vents to circulate the humid air around the subfloor space, eventually driving it out of the property. This air is then replaced by dry air from the outside.

What the ventilation system does is remarkably simple, and yet it is also remarkably effective. By removing this humid air, subfloor ventilation removes one of the key conditions for mould growth, making it difficult for damaging mould to take hold.


What can happen if we do not treat subfloor mould?


While subfloor mould might be hidden away beneath your floor, it is not something that can be ignored. Mould has a habit of spreading easily, and it can quickly make its way up into other areas of your home, causing damage and a generally unpleasant environment. Mould in the air in your home can also cause a variety of health issues.

Let’s take a look at some of these problems.

  • Mould grows very easily, becoming a problem all over your home.
  • Mould can cause damage to clothes, surfaces, and other valuable items and possessions.
  • Mould spores can exacerbate allergies and asthma symptoms, creating a potentially serious hazard to health.
  • Mould spores can cause breathing difficulties even in otherwise healthy individuals.
  • Mould and damp can create a breeding ground for pest infestations.
  • Mould and damp can lead to structural issues that make the house unfit to live in.
  • Mould can be very difficult to get rid of once it takes hold as it cannot be effectively treated topically. Instead, systematic issues with damp and humidity must be addressed.
  • Mould becomes more expensive to treat and remove the longer it is left.
  • All of the above means that the presence of mould can seriously devalue your property. You have invested money, time, and effort in your property, and this should not go to waste.

Damage to your home. Health problems for your family. A reduction in property value. All of this can result if you choose not to treat subfloor mould.

What is the process for removing mould and increasing ventilation?


Your subfloor space is not like the rest of your property. You cannot simply open a door or window to increase the ventilation under the floor, nor can you easily access this space to remove mould. Instead, the processes of removing mould and increasing ventilation happen together, and they are achieved with an effective subfloor ventilation system.

Here’s how the process works from start to finish:

You remain vigilant in your home, and keep a lookout for signs of damp and mould. These may include:

  • Musty smells
  • Patches of damp or moisture on surfaces
  • Breathing difficulties or worsening asthma symptoms
  • More pests or infestations in the home
  • Increased humidity in the home atmosphere
  • When you suspect that there might be mould present in the home, or that you need to increase ventilation to prevent mould in the future, it’s time to call a subfloor ventilation professional.
  • The professional, or their team, will visit your property and begin an inspection and a survey. This will tell them where exactly the mould and dampness are located, as well as where they can install the various components of the system – for example, the exhaust vent.
  • They will then get to work installing the system. The duration and cost of the stage of the project will depend on the layout of your subfloor space, as well as the type of system you decide to have installed. The ventilation installer will be able to inform you in advance.
  • You will need to talk with the installer and set up a regular maintenance schedule. Your subfloor ventilation system will not need too much maintenance to keep on performing at its best, but a regular checkup can keep your home free from damp and mould.
  • Remain vigilant and watch for patches of damp or mould. If the solution is working correctly, both of these elements should have reduced.


Why should you use a ventilation specialist?


You will have noticed, in the last section, we are talking about subfloor ventilation professionals and their teams. But why is this? Can’t you simply install the solution yourself? Wouldn’t this save you money?

Well, you could do this. After all, anyone can carry out a job in their home if they have the right tools and expertise.

However, unless you have professional training in the field of installing and maintaining subfloor ventilation systems, you should avoid this task, and instead leave it up to the specialists. Here’s why:

  • As with any major DIY job, there are a number of different dangers involved. You risk injuring yourself and others.
  • As you are working with the subfloor space, you could end up weakening foundations and reducing the value of your property. You might even render your property unsafe.
  • Without the right expertise, installing subfloor ventilation could mean a whole lot of disruption without much reward. If your subfloor ventilation system is not doing what you expect it to, then the whole thing has just been a waste of time, money, and effort.
  • The objective is to make sure that your home is free from damaging mould. Trying to save money by cutting corners will make this difficult.
  • Your ventilation specialist will be able to guide you to ensure the system is correctly installed, meaning that you are protected in the event anything goes wrong
  • Your ventilation specialists will be able to help you maintain and look after the system going forward, helping you get the best results in both the short and long term.
  • Your ventilation specialists will have access to all of the tools and equipment required to complete the job.
  • Your ventilation specialist will have the expertise required to decide which type of subfloor ventilation system to use including the appropriate designed system, which will help you to make sure you have the right solution for your property.

These are important considerations to take into account. We all want to save ourselves money, and to make sure that we get a good deal. But, by cutting corners, we can often find ourselves in the opposite situation. Only take on the job yourself if you are certain you have the skills and equipment required to see it through.


Is subfloor ventilation noisy?


You invest in subfloor ventilation because you want to protect your home and make it more comfortable. With this in mind, you need a solution that will not prevent you from enjoying your home. This brings us to the question of noise.

So, are subfloor ventilation systems noisy?

While subfloor ventilation is not a silent solution, most would not consider these systems noisy. The level of sound produced is relatively low, and it is certainly nothing that could be compared to a car engine or a vacuum cleaner.

The system itself is generally run during the day because the external air entering the property is drier during the day. This means that the sound of the system running will not keep you up at night, even if you are a light sleeper. Any residual noise will be difficult to hear over the usual sounds of day-to-day activities.


Positive Pressure v’s Damp Air Exhaust Systems


There are different types of ventilation available to you, however there is only one type that should be used to remedy a damp, musty subfloor area, and that is a damp air exhaust system.

With this system, negative pressure is created as the volume of air removed from the subfloor space, this is then replaced with dry outside air.


  • Effective management of moisture and odours
  • More control over the system as the specialist can choose where air is extracted from



About PureProtect: How We Can Help


Here at PureProtect, we have spent years helping our customers deal with mould problems at their properties. We install solutions that safeguard the health of your family and also the value of your home. You can count on us to do so in a careful, considered, and cost-effective manner.

To learn more about what we can do for you, reach out and speak to a member of our team today.

Call to discuss options to improve sub floor ventilation in your home

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