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There is a big gap between the wall of my house and patio concrete. I am looking for expert advice on how to fill this gap. Any hepl would be appreciated.
Welcome to the Bunnings Workshop community @sushillch. It's brilliant to have you join us, and many thanks for your question about filling gaps.
Thanks for sharing the photos — those gaps are definitely wider than what we’d typically expect to see in a standard expansion joint.
Generally, for gaps up to around 10mm wide, the standard method is to insert a foam backing rod (also called a gap filler rod) into the joint and then seal over it with a flexible polyurethane sealant like Sikaflex 11FC. This combination allows the joint to move slightly over time without cracking or breaking the seal. However, in your case, the gap looks significantly wider, and it suggests there’s been quite a bit of movement in the area — more than what you'd expect from normal settling or expansion.
Before attempting to fill it, it would be a good idea to have the area assessed, as it might indicate a structural issue with the patio slab — possibly related to ground movement, poor compaction, or separation from the house footing.
If an assessment confirms that there’s no major structural concern, you could potentially part-fill the gap with mortar or a dry-pack mix to reduce the depth, then apply Sikaflex 11FC over the top to provide a flexible seal. That said, filling it without understanding the cause of the movement may just result in the issue returning later on, so it’s best to get that confirmation first.
Please let me know if you have any questions.
Mitchell
