Gap between countertop and splashback

Really depends on how big this gap is. Can you not do a silicone line to first fill that gap then wait to cure and do one as normal over the top. Only other option if your not prepared to move the worktop is put a upstand around that matches the worktop, sure they come in different size of around 70-100 mm ? Id question why the tradesman who fitted the worktop never scribed it to the wall. Hope it helps. PPS

Hi there, sorry to hear you've had this problem occur as there's no real excuse for leaving a gap between worktop and bottom of tile line as mapping tile layout correctly is paramount to ensure even lines and minimal unnecessary cuts causing wastage, my advice would be to use a 3ml hardboard/spacers laid temporarily on the sideboard and taped into position to create a straight baseline to work from, once tiles have been laid and have set the board can be removed and filled initially with grout to join tile and worktop before sealing with waterproof anti fungal silicon. I hope this is of help. Steve