S
StevieBoy
Its an expansion joint. If you fill it how can there be room for movement, something will give.
Have a look here you can match to most tiles or grout colours from here
http://www.countyconchem.co.uk/graphics/sealant colour charts/ottoseal-s100-sealant-colour-chart-large.jpg
Anyone would think we're expecting major earthquakes or something.
That's a very nice website - I can't see how you order a tube from them unless I'm missing something.