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Welcome to the Bunnings Workshop community @Amanda26. It's wonderful to have you join us, and many thanks for your question about filling gaps.
It looks like the images did not come through on your post. You might like to try uploading them again, and if you continue to have trouble, let us know and you can email them through to us and I can post them up for you.
From your description, it sounds like you are dealing with expansion gaps between the house and the concrete slabs, which is very common at both patios and around paths. Even gaps around the width you have mentioned are considered normal, as the concrete needs room to move independently from the house.
The usual approach is to start by removing any loose or deteriorated material from the gap, including old sealant that has broken down. Once the gap is clean, a backing filler rod can be pushed into the joint. This helps control how much sealant is used and ensures the sealant performs correctly. The filler rod should sit roughly about 7mm below the concrete surface.
You can then fill over the top with a flexible polyurethane sealant such as Sikaflex 11FC. This product is well-suited to expansion joints and will cope with movement without cracking. For wider gaps, especially over longer runs, you may find you go through a lot of standard cartridges, so it can be worth considering the larger sausage packs and a compatible gun if you are doing a significant length.
Once the sealant is applied, smooth it off neatly with a wet, soapy finger and allow it to cure as per the instructions. Here's a helpful guide: How to fill a joint in a concrete slab.
Please let me know if you have any questions.
Mitchell
