# Forum Home Renovation Pools, Spa & Water Features  Caulking expansion joint between coping tiles and sandstone crazy paving

## hemp

I'm trying to caulk the expansion joint between the pool's coping tiles and the sandstone crazy paving. I'm using Sikaflex Pro and making a hash of it. It's so elastic that it is hard to keep it within the 15mm gap between the coping tiles and the sandstone crazy paving. Also, any that escapes is absorbed into the pavers, leaving some impregnated even when it is scraped off after it has dried. I'm using soapy water to assist, but the caulk is inclined to move when I use the smoothing tool leaving lumps and swirls of caulk in the gap. I thought I'd try masking tape on each side, but the irregular nature of the sandstone crazy tiles makes it hard to obtain a seal. I'm also concerned that when I remove the tape, the caulk will move with it. 
Any ideas?

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## Pulse

Are you using poly backing rod to fill onto? The smoothing tools in the paint aisle at bunnings seem to work well but you have a large gap and no smooth edge to work against which is why it is hard. What about using your finger? 
Cheers
Pulse

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## hemp

The tiler may have used a rod. I don't know because he also used some caulk, though he left it hollowed - maybe 5mm below the coping tile and sandstone paving. I wanted to build it up to be as near to flush as possible.

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## hemp

Well, I had reasonable success using an expensive Scotch Blue masking tape on both sides of the expansion gap. It was worth the cost, as it stuck well to the tiles without any of the Sikaflex Pro sneaking under the edges. As the pool is kidney shape it was fiddly fitting the tape around curves. The caulk edging is neater along the straight edge of the coping tiles, but not too bad where it meets the irregular crazy paving. I used a flexible 40 mm filling blade to spread the caulk flush with the coping tiles and paving_._ I removed the tape as soon as I completed a 2 metre section without too much adhesion to the masking tape. I used 3 x 600ml tubes to fill the 30 metres of joint which varies in width from about 15-25 mm, and depth around 20mm. The relatively shallow depth is because the paving contractor had put some caulk in when the pool was built, but he did not fill it up to flush. It was also a rather ordinary gray, but I used a sandstone colour to blend better.

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