Building or renovating a new home is a huge endeavour, with plenty of challenges along the way. While we’d like to think that your builder should be able to expertly guide you through the process, it can help to develop your own broad understanding so that you can easily follow along, asking the right questions when needed.
In our Ozzbuild Explains series, we’re breaking down some of the more common technical aspects of building, giving you insight into smaller details that could make the world of difference down the line. This time, it’s all about window flashings.
What are window flashings?
Window flashings are something that bridge the gap between a window and the wall it is installed into. They create a weatherproof barrier so that moisture cannot pass by the top, bottom or sides of a window and into the internal area of a wall.
Why are they important in a home?
Flashings keep our walls, insulation, internal brickwork (if you have it) and plasterboard dry. Basically it protects the inside of our homes from anything inside the wall cavity – even air can be stopped if you use the right flashings! This goes towards creating an airtight home that gives better insulation values.
What type of window flashing works best?
At Ozzbuild, we use a wide tape that is made from polypropylene and butyl rubber. It works as part of the complete wrapping system we install on the home.
What’s the relationship between waterproofing and window flashings?
Wind-driven rainwater causes major damage to homes, so having window flashings installed can stop this from happening.
What happens when a home does not have window flashings or they are installed incorrectly?
Unfortunately, many new homes are built without window flashings installed on all four sides of an opening. With a hole in the barrier, damage will occur inside the wall cavity over time. It could even occur to the building materials inside the home as moisture is allowed to easily pass between the gaps around the window and wall frame. This could become particularly problematic if you have a timber frame and it becomes wet, as it could attract termites.
It is not uncommon in heavy rain for windows and doors to leak through the small joints where they are screwed together – even the sub sills that carry the water in the bottom of the window frame can sometimes overflow if they cannot cope with the volume of water they are taking on. If you have no sill flashing (bottom piece), this water will leak into the home, instead of being directed outside.
Do exterior doors need flashing?
Doors need all four sides of the opening flashed just like windows. Most importantly, they need the sill flashing (bottom piece) to be installed before the door is installed – it must start from outside and return up behind the sill, creating an angle-like barrier. This is rarely done! At Ozzbuild, we do this with waterproofing membrane on our balconies that have sliding doors installed on them.
What are some common misconceptions around window flashings?
The main misconception is that people do not know you need them and Australian standards are not overly strict on this, unfortunately. Some volume-type windows come with a flashing pre-installed at the bottom, but it does not carry right through below the window so is almost useless.
Ozzbuild Director, Ryan Ward, did his research into flashings by looking at how builders in places like North America and Europe work – the extremely cold climate in winter means that the standards for water protection and insulation are very high. The products we use to flash and protect the home originate from Europe.
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If you want to learn more about the importance of window flashing or are ready to engage a technical builder with experience on challenging sites, get in touch with the team at Ozzbuild today!