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I have a flat colorbond garage roof and there is a leak when rains are heavy.
I cut the roof plasterboard and sarking, and found rainwater back flow from the flashing as you can see from my images.
I want to fill the gap between flashing and roof sheet as the gap is around 1cm so water cannot get in.
Which materials would be suitable to fix it?
I have some ideas in mind but don't know which one is the better. Or if you have better ideas, please give me some advice. Thank you.
1. Selleys 310g Translucent Roof And Gutter Silicone Sealant
2. CAgroup 100mm x 10m Weatherproof Byute Flash Flashing Tape
4. Selleys 180g Spakfilla Rapid Gap Filler + roof sealant
5. Fastfix Wet Shield 1kg One Coat Instant Waterproofing
Also, someone tried to fix it with excessive sealant before, should I remove it before applying new fix?
Welcome to the Bunnings Workshop community @zacw0001. It's wonderful to have you join us, and many thanks for your question about sealing a gap.
That’s quite a large gap to cover, and it will need a more durable fix than just a standard gap filler. I’d recommend using a product like Sikaflex 11FC, which is a strong, flexible polyurethane sealant designed for construction joints. Because the gap is around 1cm, you’ll probably need to apply it in two separate beads to build it up properly and make sure it seals the area. Once you’ve done that, you can go over the top with Weatherproof Byute Flash Flashing Tape for added protection and to give you a belt-and-braces solution.
It’s also a good idea to scrape back and remove as much of the old, excessive sealant as possible before applying new product, otherwise the new sealant may not adhere properly. This combination should give you a more reliable, long-lasting seal against heavy rain.
Please let me know if you have any questions.
Mitchell
