How to Choose Waterproof Windows

Australia’s diverse climate and occasionally extreme weather conditions make water resistance essential when designing and building modern homes. In particular, windows play a crucial role in protecting buildings from water ingress.

The importance of water-resistance

Any opening in a building, like a window, can create vulnerability to poor weather conditions. Without adequate water resistance, any building can quickly suffer from a variety of issues, including:

• Leaks and dampness, which create discomfort for occupants

• Mould, which can be harmful to health

• Timber rot, diminishing structural integrity

• Reduced energy efficiency, because moisture affects insulation performance

Inadequate waterproofing reduces the level of comfort in a home, but it also affects its longevity and efficiency. With many areas of Australia subjected to heavy rain and storms, a lack of water resistance can cost occupants in money and peace of mind.

What makes a window waterproof?

Water resistance is tested in Australia according to AS2047, the national standard for windows in doors, and specifically the Water Penetration Resistance Test (W Rating). This measures the maximum pressure at which no water penetrates beyond the inner face of the window. A higher W Rating number means better resistance, but the required rating a building needs to meet depends on its location, exposure and size.

The performance of your waterproofing relies on three design principles:

• Deflection: The design of the frame and sash, and how they direct water away.

• Drainage: Paths for any water that does enter to escape downwards.

• Drying: Proper ventilation that allows moisture to evaporate.

Factors to consider when selecting windows

Materials

The materials used to construct windows will play a significant role in weather performance and durability. For example, aluminium is an inherently water-resistant choice that doesn’t swell or warp when exposed to moisture. Timber is another option with strong insulating properties, though it can be subject to rot and moisture absorption without regular maintenance and protection.

Our composite AliClad frames combine the resilience of aluminium with the thermal efficiency of timber, offering long-term protection and minimal maintenance.

Glazing and sealing

For the highest level of water resistance, we recommend using double glazing in your windows. Not only does this contribute to better energy efficiency overall, but it also specifically helps to reduce condensation. Alongside double glazing, high-quality seals can ensure moisture stays out of the cavity between the glass panes. Compression seals are especially recommended, which form a tight closure when the sash is locked, preventing water ingress during heavy rains.

Hardware and installation

The hardware components used in windows, including hinges, handles and screws, should all be corrosion-resistant and fitted properly to avoid leaks. For the best performance, we recommend using stainless-steel or powder-coated fittings. Always use installers familiar with AS2047 testing requirements to ensure long-term effectiveness.

Ideal window types for waterproofing

Even with the correct materials and installation, some window types naturally perform better at resisting water ingress than others, due to their opening style and orientation. In particular, awning and casement windows are excellent for exposed facades, as they close tightly against compression seals. Awning windows, in particular, allow water to drain off the exterior surface thanks to their design. Fixed windows also provide maximum watertightness when installed correctly.

Waterproofing isn’t a once-off task, however; regular inspections are essential to maintain performance. This includes inspecting the frames and seals for damage, and cleaning any drainage channels to avoid blockages. If the windows have any protective finishes, these should be recoated as necessary.

Ensuring long-term water-resistance

Achieving compliance with waterproofing requires precise detailing and high-quality products. For expert solutions, get in touch with our team at Miglas and learn more about our specialty AliClad windows, ensuring the highest level of performance with strong aesthetic appeal.