You may think because they are powered, roof fans have an advantage over roof vents, this is quite untrue.

For a start let me tell you the concept and benefits for effective roofspace ventilation – the concept is to have a balanced system of an inlet and outlet of the same volume opposing each other in each zone of your roofspace. This allows the ambient air to flow freely throughout the roofspace removing all the moist stale air replacing it with fresh air. This can be done by having two identical ventilators opposing each other in each zone of the roofspace, it is an added advantage to have them fixed in the roof covering i.e. (the rooftiles or colorbond) to give best results.

The benefits for roofspace ventilation are for a cooler home in summer and a drier roofspace in winter.

You can’t expect one fan alone with unbalanced inlet air to achieve this.


As well as drawing unbalanced air from eaves vents.  At the point of installation, they will first drag air from wherever they can find it, i.e. precious air conditioned air – from ceiling protrusions and ceiling leaks etc.  Not only that, if the ceiling is leaky enough and they are large enough they can create enough negative pressure to actually back draught combustion applicances, air finds a path with the least resistance.  As well as being a net energy user they need to be professionally installed, can become really noisy and need to be replaced frequently (especially if you run them as long as a natural system, at least every 4 years if you only run them in summer.  We reiterate not only that they are expensive to buy and install.


They are supposedly underpowered when compared to grid powered fans, however when the sun goes down so do they and they are not much use in winter when you really need them to curb condensation problems.

You would need more than one, possibly one for each zone of your roofspace and you then have the problem of getting the perfect balance of inlet air, for one, two or more for your particular roofspace. I don’t think that a salesman or a roofer is going to do it for you, you will need a scientist.

I cannot think of any real advantages for you, think about it do some research before you shell out good money on a possibility, roof fans have been banned in some states of America.


We cannot speak for other systems however we can tell you our ventilation systems are balanced with inlets and outlets of the same volume, they have design within their configuration to harness all the principles for fluid dynamics including aerodynamics and thermal currents. They will move the ambient airflow throughout your roofspace and keep your home cool in summer and a dry roofspace all year round.

For a one-off cost, never need repair or replacement, use no energy, can easily install DIY, last for decades and decades – you can’t beat that!

See Blog on this site “Warning! Read Before You Design Your Next Housing Project”.