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Hi folks, hoping for some advice and ideas for this aluminium window. The house was built in 1984 and I believe these are old Dowell aluminium sliding windows. The external flashing has become brittle and broken off in parts, and there appears to be no flashing at all along the sides. The silicone along the frame itself is very old and moss is growing in it, and the seals of the wondow itself appear to be in equally bad shape. Most of the windows in the house are like this and will ultimately need to be replaced, but this won't be happening for a few more years. What can I do in the meantime time to prevent water ingress? There is no obvious leak at present, however water is clearly getting in as the amount of condensation we experience is so severe it leaves puddles on the window sil and carpet under window. The problem has obviously been occurring for some time as there's evidence of black mould through the internal wood frame. Any suggestions to help me get afewmoreyeats out of these would be greatly appreciated!
Welcome to the Bunnings Workshop community @Tess29. It's wonderful to have you join us, and many thanks for your question about sealing windows.
Since the external flashing has become brittle and there are gaps around the window, one of the most effective ways to seal them temporarily is to use Sikaflex 11FC, which is a high-performance, multi-purpose sealant. This product is ideal for sealing gaps and joints around windows, and it adheres well to both aluminium and masonry. You can apply Sikaflex to seal any gaps between the window frame and surrounding wall. For larger gaps, it’s a good idea to insert a foam backing rod first to fill some of the space before applying the Sikaflex. This ensures you don’t use an excessive amount of sealant and gives it something to bond to for better long-term performance.
Be sure to clean and prep the surfaces before application—removing old silicone, moss, and debris will help the Sikaflex adhere properly. Apply the sealant smoothly, making sure to cover the entire gap around the window frame to prevent moisture from getting in. You can also use Sikaflex to reseal areas where the flashing has broken off or is missing.
As for the condensation you're experiencing, it's important to note that condensation on the interior of a window isn't necessarily a sign that water is entering through the frame. It’s more likely a result of temperature differences between the warm indoor air and the cold exterior surface of the window, especially in bedrooms where humidity levels tend to be higher. While condensation isn't an immediate indicator of a leak, it can still lead to moisture problems like mould, which you already notice. Sealing up the gaps will help reduce drafts and cold spots, which can help mitigate some of the condensation.
Additionally, given the signs of black mould in the wood frame, it’s important to address the mould problem. After sealing the window, you may want to clean the mould off the internal frame with a mixture of bleach and water, and then ensure the area is thoroughly dried out. Preventing further moisture from entering will also help to slow down mould growth in the future.
While this solution won’t be a permanent fix, it should help to seal the window for now and reduce water ingress until you're able to replace the windows. Keep in mind that addressing the ventilation and condensation issues in the room can also help in the long run, such as using a dehumidifier or improving airflow.
Please let me know if you have any questions.
Mitchell
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