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How to stop water going through balcony decking?

Our balcony has decking with gaps through which then water flows down whenever it rains so we cannot use the area below. What is the best way for us to seal this so that we don't have water going through and can actually use the covered space below. Attaching images of the decking.

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MitchellMc

Welcome to the Bunnings Workshop community @ishjadh. It's fabulous to have you join us, and many thanks for your question about waterproofing a deck.

Decking isn't typically designed to be completely waterproof, as gaps between the boards allow for drainage and natural expansion and contraction. Sealing the gaps might seem like an easy fix, but it can lead to unintended issues, such as water pooling on the surface or being redirected in ways that could cause damage to the structure.

Before attempting to waterproof the area, it's important to consider where the water would go if it were sealed. If you prevent it from dripping through, you'll need to capture it and redirect it away from the space below. This would typically require installing an under-deck drainage system, which involves fitting a waterproof membrane or drainage panels beneath the decking to collect water and channel it toward a gutter or drainage outlet. However, these systems need to be carefully installed with a proper slope to ensure water doesn’t pool or leak into unwanted areas.

An alternative approach would be to consider whether you can prevent water from reaching the deck in the first place. Would it be possible to install a roof or shelter over the deck? A pergola with polycarbonate roofing, for example, could shield the decking from rain, keeping the space below dry while still allowing light through. This might be a more effective and long-term solution compared to attempting to waterproof the deck itself.

Please let me know if you have any questions.

Mitchell

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