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I’m planning on tiling the front porch and the concrete slab in front. The concrete slabs have a bullnose edge and the expansion gap is 10mm wide. Is the best way to silicone the expansion gap between the tiles? Seems like a wide expansion gap to silicone or is there another way to make it look tidy?
Welcome to the Bunnings Workshop community @gdjdjdja737. It's brilliant to have you join us, and many thanks for your question about tiling over an expansion gap.
When tiling over a concrete slab that has an expansion gap, it’s important to ensure the joint transfers through to the tiles. You should tile up to the edge of the expansion joint on either side, but do not cover the joint itself with adhesive, as this could cause the tiles or grout to crack if the slab moves. Make sure the grout lines of the tiles align with the expansion joint above, so the joint appears straight and continuous. Instead of using grout directly in this area, fill the joint with silicone, which is flexible and can accommodate movement. The tile-to-tile gap over the expansion joint doesn’t need to be as wide as the slab’s full expansion gap; for example, you could leave a 5mm gap between the tiles and fill that with silicone, allowing the expansion joint to function properly while keeping the finish neat.
I've created a rendering below to illustrate.
Please let me know if you have any questions.
Mitchell
It shouldn’t be an issue, @gdjdjdja737, as the concrete on either side of the expansion joint will well support the tiles. Obviously, it would be ideal if every part of the tile were fully supported, but in this case that’s not possible given the joint. The key thing is to make sure you don’t run adhesive or grout directly over the expansion gap, otherwise the movement in the slab could cause cracking. By leaving around a 5mm gap between the tiles and filling it with silicone, you’ll allow for movement while still keeping the finish looking neat.
Mitchell
