Summer in Australia can be an uncomfortably warm time if you don’t live in a home with air conditioning. While it may not be the cure-all solution to a hot house, installing a roof ventilator (also known as a whirlybird), or several depending on the size of your home, could be a relatively affordable way of managing the internal temperature of your home.
That being said, Jim’s Heating and Cooling advises that a whirlybird could come in handy even if your home also has air conditioning, by helping to speed up the process of cooling your home.
What is a whirlybird?
A whirlybird is a small cylindrical dome attached to the roof of a home, with numerous ‘fins’ allowing it to spin. As online renovation resource BUILD explains, as it rotates, a whirlybird creates a vacuum which sucks warm air up and out of a roof cavity (the space in-between your highest ceiling and the top of your roof).
Some whirlybirds are mechanically driven and can turn continuously, while others require wind to operate.
Are whirlybirds really effective?
It’s important to note that a whirlybird doesn’t offer the direct cooling effect that an air conditioner or ceiling fan might. Whereas an air conditioner cools a room by pumping cold air into it, and a ceiling fan can help cool the occupants of a room by creating a breeze , a whirlybird generally only serves to remove warm air from the uppermost part of a home.
However, they can still contribute to keeping your home cooler in the warm months. According to Solar Whiz a whirlybird can help to prevent heat transferring from air trapped in the roof cavity to the ceiling. This in turn may limit the extent to which your home can heat up and reduce reliance on your air conditioning system (if you have one) which could save you energy and money.
Solar Whiz also notes that a whirlybird may also prevent the accumulation of humid air, and subsequently ensure that moisture doesn’t build up in your roof cavity, which can prevent the growth of mould and/or mildew.
How much does a whirlybird cost?
Whirlybirds themselves are not particularly expensive compared to having air conditioning installed. At the time of writing, Bunnings’ online store offers a wide range of wind-driven whirlybirds, with the cheapest one costing $69 and the most expensive one costing $147. A mechanical whirlybird from Bunnings will cost from around $154, up to $2,421.
If you’re planning on installing the whirlybird yourself, purchasing it will be your sole expense (save the cost of any necessary tools you don’t already own).
Depending on what your roof is made from, you may need to drill a hole in order to install your whirlybird(s). Twista Roof Ventilators advises that you may also require a hammer, screwdriver, and elbow-high safety gloves. Bear in mind any safety implications of carrying out a job like this by yourself, such as falling from the roof or inadvertently coming into contact with electrical wires. Also take care not to cause damage to your roof in the process.
Leave the installation to a professional may be a more straightforward option, although you may see your total expenses increase significantly.
How much does it cost to have a whirlybird installed?
If you hire a professional to install your whirlybird(s) for you, the total cost of their services will depend on whether they’re supplying and installing the whirlybird(s), or just installing a whirlybird that you’ve already purchased.
To give you an approximate idea of what you might pay, the Sydney Roof Doctor charges the following amounts for the supply and installation of ‘regular’ (e.g. non-mechanical) whirlybirds:
- $448 for one whirlybird
- $748 for two whirlybirds
- $953 for three whirlybirds
- $1,234 for four whirlybirds
And Roof Vents Australia charges:
- $520 for one whirlybird
- $860 for two whirlybirds
- $1,090 for three whirlybirds
- $1,300 for four whirlybirds
However, according to Roof Vents Australia the amount you end up paying for installation may be influenced by factors including what your roof is made of, how easy it is to access, and how far the contractor has to travel for the job. It could help to obtain quotes from several different contractors to get a sense of what your options are and to avoid paying more than you need to. Regardless of who installs your whirlybird(s), you will generally pay less per whirlybird the more you have installed.
How many whirlybirds do I need?
You may assume that one whirlybird is all you’ll need, but depending on the size of your home, you may need as many as four.
According to to the Sydney Roof Doctor:
- A house with 1-2 bedrooms will generally need two whirlybirds
- A house with 3-4 bedrooms will generally need up to four whirlybirds
- A house with 4-5 bedrooms will generally need four whirlybirds
Based on these recommendations, a good rule of thumb may be that you should install one whirlybird per bedroom in your house.
Is a whirlybird right for my home?
Before you decide to install a whirlybird (or several) on your roof, you may want to consider whether your home will see enough of a benefit to justify the cost. This will largely come down to the size of your home, as well as how well it’s currently ventilated.
A larger home means a larger cost
If your home is relatively large, with four or more bedrooms, you may end up paying more than $1,000 to have the appropriate number of whirlybirds installed. But again, by shopping around and obtaining quotes from a number of different contractors, you may be able to find an installer that offers you more bird for your buck.
Is my house whirlybird-friendly?
According to the Roofing Professionals Westside, whirlybirds are best suited to well-ventilated roof cavities that allow for air circulation. If a roof cavity has inadequate ventilation, then a whirlybird may not be an efficient way of removing warm air from your home.
You may decide to have additional ventilation built into your house in order to improve the future efficiency of any whirlybirds that are installed, but it goes without saying that this would very likely increase your total costs significantly. It may be worth considering whether the benefits of having a whirlybird installed outweigh the financial burden of not only the whirlybird itself, but also the remodeling necessary to make whirlybirds a viable option for your home.
What are the ways I could pay for my whirlybird(s)?
If you’re having more than one whirlybird installed, you may either not want to or not be able to pay for it out of pocket. If this is the case, there are several other ways to pay for home improvements, including:
- Personal loan
- Credit card
- Making use of a redraw facility to withdraw any extra money you’ve paid into your home loan (if your mortgage offers this feature)
If you need to borrow money to fund the job, be sure to pay close attention to factors such as the interest rate you’re charged by the lender, any fees that apply and whether you will be able to afford the repayments.