If you have a gap between the areas where you’re going to install your tile splashback, such as space between two cupboards, you’ll need to create something to support the tiles. Use a stud finder to locate a stud wall or a noggin behind the wall and mark its location. Use your long spirit level and lay it across the gap, this gives you the straight line you need, so that you can butt your timber up against it. Hold the timber against the wall and flush with the spirit level, then drill it into place.