Roof Ventilation in Australia (All You Need to Know)

When you want to make your home more comfortable, the last thing that you are likely to think about is working on the roof. However, you should take this aspect into consideration. If there’s proper roof ventilation, then the rest of your house will be quite comfortable. This is especially during summer months when temperatures can go as high as 70 degrees Celsius. This can heat up the whole house, prompting you to use an air conditioner to control the temperature to manageable levels. Even though using an AC will help, the downside to this is the huge energy bill that you will get. With proper roof ventilation, you will be able to keep your house cool and minimize the amount of energy that you will need to cool it down.

Proper roof ventilation will also minimize the chances of mold growing inside the house as moisture levels will be reduced. There are several ways that moisture can get on your roof. During winter months, the warm air will rise and set as condensation on the roof. Also, the warm air might also be caused by an exhaust system in your house. In case you have an exhaust system somewhere in your house, let’s say in your kitchen or in the bathroom, it means that warm air is being pushed upwards. Take into consideration your air circulation needs. It might be advisable to put ducting from exhaust fans on the external part of the building.

How to Set Up a Good Roof Ventilation System for the Roof

Setting up a good roof ventilation system is not that hard. You only need a fan and a vent to get started.  The work of the vents is to let out bad air and to bring in the fresh air. The fans help accelerate this process. You can get different kinds of fans at Universal Products, including efficient fans that use solar power and roof ventilators that are powered from the mains.

It’s essential that all roofs have an air circulation system in place. Make sure to assess the area first systematically, so that you can spot areas where air can enter and exit the room. This includes any spaces or vents between air boards and tiles. When setting up your air circulation system, make sure the vents that let in fresh air are placed lower than the vents which draw out air from the roof. This is because the fresh, cool air will push up the warm air and cause it to escape through the highly placed vents.

The vents that draw in the cool air from outside should preferably be set up in a cool, dry place. This should be away from direct sunlight. Consider placing it below the eave to keep the air on the roof cool.

How Much Ventilation is Needed for the Roof Space?

Ideally, 10 air changes should be enough, but if there’s a lot of moisture in your roof, then you should aim for slightly more air changes. Therefore, when you’re choosing a fan, make sure that you get one that can handle the job.

When you want to determine the right size of roof cavity, here’s how to do it:

The ½ height of the roof x length of the roof x width of the roof

Then multiply the resulting figure with 10. This will give you the number of air changes that your roof space needs.

To make your work easier, consider using an online calculator to come up with the correct figure for the fan capacity that you need.

For good roof ventilation, consider placing non-powered vents as well, in addition to the fan. These vents will allow fresh air to come inside the house. Just make sure that the vents are placed on the lower part of the roof. Ideally, the size of the non-powered vents should be similar in size to the vents of the fan. Space out non-powered vents evenly throughout the roof space for better fresh air intake.

What’s the Best Roof Ventilation?

There are different roof ventilation methods. You can find main powered and solar-powered fans at Universal Fans. Both products are good. The option that you go for will mainly be determined by what your specific needs are, but both these options are better than using a whirlybird. If you go for a whirlybird, you will need more than one, but if you go for a main powered fan, you will just need one.

Solar-powered fans are quite good for roof ventilation. If you have a small house, you will just need one of these, but if you have a bigger house, you will need at least two. This is much less than the 15 whirlybirds that you would need to do the same kind of job. Also, a lot of people tend not to like how so many whirlybirds look up there on their roofs. Solar-powered fans don’t cost anything since they use energy from the sun. They also move a large amount of air in an hour, and they are much quieter than other options in the market.

You can also use a main powered ventilator for your roof ventilation. The main advantage that they have over solar-powered ventilators is that they can be used overnight. However, they will increase your energy costs. They move a lot less air than the solar-powered ventilators and have different features, including speed controls.

Solar-powered and mains powered fans offer a better option than whirlybirds. This is because whirlybirds mainly rely on the wind for them to work. Unfortunately, it so happens that the days that are hottest are the ones that there’s no wind. Therefore, you might end up stuck in a hot house with no reprieve. You will be much better off using a powered fan for your roof ventilation.

The Cost of Solar-Powered Ventilators

The cost of solar-powered ventilators has generally gone down. The most expensive parts of the ventilators are the motor and the solar panel. If you want a quality unit, expect to pay between $500 and $900. You will have to fork out $200 for each whirlybird that you buy, and you need at least four for a regular sized home. This makes it so much more worthwhile to invest in a solar-powered ventilator for your roof ventilation.

  • Performance

You need to consider the performance of the ventilator that you buy as compared to other ventilators in the market. Solar-powered ventilators perform much better than wind-powered ones.

To know how well the ventilator performs, you need to look at two key features. These are the wattage of the solar panel and the diameter of the extraction fan. Even though the ventilators have other features, these two are the ones that will make a big difference when it comes to roof ventilation.

  • Warranty

A lot of manufacturers will give you a 10-15-year guarantee on the solar panels that you buy. Nevertheless, this guarantee will not cover the parts. You will get a 1-3-year guarantee on the motor.

  • Installation

There are lots of products that are imported from other countries, so you need to be careful to select a product that’s appropriate for the unforgiving Australian weather.

A singular, one size fits all flashing can lead to problems such as leaking, like in old-fashioned inferior quality skylights. When looking for what to buy, keep an eye out for roof flashings that have been customized to suit the curves of your roof.

Market Prices

Wind Vents from $80 to $350

Wind ventilators are quite inefficient when it comes to providing roof ventilation. They can move approximately 80-100 cubic meters of air an hour. This can be compared to a static cap. The reason why they are quite popular in Australia is that they are cheap.

The cost of the wind vent is largely determined by its quality.

Here are the main things to be on the lookout for:

  • It should have a fan blade, as this will make a great difference in enhancing air extraction.
  • The diameter of the product matters. A 250mm-350mm diameter is ideal for a standard home.
  • How long the product will last matters greatly. There are many inferior quality products in Australian homes, which are also noisy.

Budget Solar Roof Vents from $100 to $250

If you want a solar-powered unit for your roof ventilation, be prepared to fork out a large amount of money, if you want to get a quality unit. Cheap solar-powered vents are cheap because they compromise on the quality of the solar panels and the motors.  Both can significantly reduce the quality of performance of the equipment, making them no better than wind vents. Moreover, the guarantee is usually just for just a little over a year. If this is the most that you can afford, you are better off going for a superior quality whirlybird for your roof ventilation.

Quality Roof Vents from $500 to $900

We have looked at how to choose a quality product. But there are some other considerations that you need to keep in mind as well.

How Much Can Roof Ventilation Reduce the Temperature

There are many factors that affect ventilation in your house. From how well your house is insulated to the kind of material used on your roof to whether your tiles have sarking to color bond roof materials that tend to retain more heat. If your tiles don’t have sarking, then cross ventilation can possibly happen. If you want to know how well your roof ventilation will work, the best thing to do is to insert your head into the roof cavity and gauge the temperature.  Since the air in your roof cavity can spike to more than 60 degrees Celsius, allowing cooler air into the roof will make a huge difference.

How Many Eve Vents Are Needed?

There are multiple factors that affect this aspect.  This includes whether your tiles have sarking or not. To help you come to a good conclusion, what you need to do is to open the manhole in the ceiling. If you notice that a great amount of air gets drawn out yet you have already installed the ventilation, it means that you need more vents.

Do They Run at Night?

Since whirlybirds need wind power to operate, you cannot operate them at night. Similarly, you cannot run solar-powered ventilators at night. However, air will be able to flow in and out of the vents naturally.

Battery Backup

A lot of customers always like to request for battery back-ups to ensure good roof ventilation. However, these have some downsides as well, which you should keep in mind.

  • Most batteries only come with a 1-year guarantee. You will need to assess your batteries after every 1-2 years and replace them.
  • Batteries cannot handle severe temperatures. A lot of battery operated products have been recalled many times due to the fire risk that they pose.
  • Most of the sun energy will be used up for charging the battery rather than for ventilation.

Cloudy and Rainy Days

The ventilator will still work and pull moisture out of the roof cavity. There will really be no need for the ventilator to work at full capacity. Since roof ventilators draw air from the outdoors, the outside environment will greatly affect the kind of impact that the ventilator has on your home.

5 Roof Ventilation Myths

Having good roof ventilation is a great way to ensure that your house stays in good condition by preventing mold growth, mildew and insects from invading your home. It also helps to keep your house cool and considerably reduces your energy bills during hot months. Unfortunately, a lot of owners think that installing a roof ventilation system might be too much of a hassle or it might be too expensive.

Here are some other top myths that people believe about roof ventilation.

  1. Roof ventilators are just suitable for hot summer months. While they considerably help during hot months, especially when you don’t have an AC, they are equally important during winter too because they help prevent moisture build up in your roof.


  1. You need many vents for good roof ventilation. Since you will be making holes in your roof, the fewer the holes that you make, the You will usually just need to make one small hole to do a job that up to 15 whirlybirds can do. This reduces the need of you making multiple holes on your roof.


  1. Whirlybirds and non-powered vents are just as effective as solar-powered and mains powered ventilators. The truth is that powered ventilators move significantly more air volume than whirlybirds and non-powered vents to help keep your home dry throughout the year. A solar-powered ventilator can do the job of 15 whirlybirds. Also, since it uses the sun for energy, you won’t even have to worry about your energy bills.


  1. You will lose too much heat from your home in winter because of the powered ventilators. The truth is that ventilators are made to ventilate your attic space only. If you realize that you are losing heat in the main part of your house, this means that your insulation is not good.


  1. All roof ventilators are the same. This is not true. For instance, solar-powered ventilators provide much better roof ventilation than whirlybirds. They can move 10-15 volumes of more air than a whirlybird can. Moreover, solar-powered ventilators use solar power, so they don’t increase your energy bills. Solar-powered ventilators have a special flange system that thwarts air leakage and guarantees many years of maintenance-free usage. It’s made from superior quality material that gives you peace of mind and is easy to operate.

Bad Ventilation Leads to Poor Air Quality

By having good roof ventilation, you will considerably boost the quality of air in your house. Bad ventilation can encourage mold growth and mildew due to the amount of moisture that will build up in your house. Mold and mildew can lead to many health problems, like respiratory and digestion problems. It could trigger asthma attacks, allergies and bowel issues.

Does Roof Ventilation Really Work?

Let’s talk a bit about insulation before we answer the question “Is roof ventilation effective?”

The ancient Egyptians were among the first people in the world to insulate their homes, using asbestos. However, this was not a very good idea. Since that time, home insulation has greatly improved, and it’s much cheaper and easier to set up. Insulation is effective because it traps air, but for it to work, the air must be still.

However, it’s not a good idea to connect the rest of your house to your roof to regulate the temperature and prevent mold growth in the rest of your house.

  • Non-powered roof ventilation will only move a small amount of air. While electrically and solar-powered ventilators can move significantly much more air, they also have their own challenges depending on the season. It’s just much better to minimize insulation gaps.
  • The attic, whether with roof ventilation or not, can get quite hot during summer and can reach freezing temperatures in winter. There isn’t much difference in the temperature, especially when there’s insulation in place.
  • How airtight and well-insulated your ceiling is essential when it comes to heating and cooling. Insulating the top of your ceiling minimizes the usefulness of having a slightly low temperature during hot summer months. So, before the powered ventilators were introduced, whirlybirds did indeed make a difference during hot summer months, but this is no longer the case.
  • Using internal air through ceiling ventilation to feed the roof ventilation machine causes the hot summer air to get inside the house through windows, doors and other entry points. This will overload your AC. Realize that your home doesn’t have an endless supply of cold air to be ventilated through the whirlybird.
  • Dampness can also come from outside the house. Well-ventilated homes are still at risk of growing mold and mildew, just as non-ventilated houses. The best way to handle this is to ensure that you have efficient roof ventilation devices that will minimize temperature oscillations inside the house. You can set up humidity sensor fans in your bathroom in addition to door ventilator grills. Exhaust fans should be set up in such a way that they draw humid air fast out of the house.
  • Installing a vent inside your house on the ceiling will allow for hot air to be pushed up by the whirlybird. This will require that you get up on the roof to close it a couple of times a year. This can be quite risky, especially for elderly folks. Moreover, the vents might not seal tight.
  • During winter months, moisture can be an issue on the roof. Therefore, make sure the kitchen range hoods and bathroom fans get ducted straight outdoors through a tiled or a metal roof deck.
  • A roof ventilation machine which has indoor ceiling ventilation can create the additional issue of attracting pollen from the outdoors into the house. This can lead to asthma attacks and other health issues.


If you want a relaxed and comfortable home environment, then you must have proper roof ventilation. In case of condensation building up on your roof, go for a more efficient ventilator, such as the ridge ventilation.

Focus on having a consistent insulation on the whole building. Plan ventilation for your bathrooms and kitchens in such a way that you take into consideration where the humid air is leaving the room and where air is originating from so that you can draw that air outdoors.

To minimize cases of mold growth, make sure the temperature inside your house is consistent so you can prevent huge temperature fluctuations.

If sarking is set up in your roof system, then it’s advisable to get roof ventilation. This is because moisture is likely to build up on such roofs because of proper air circulation. However, they cannot cool the house.