The space between the tiles should be uniform. Use spacers if your tiles don't come on mesh sheets. The larger the tile the larger the space should be between them. Some do_it_yourselfers will make the mistake of pushing tiles too close together to reduce grout lines. Without enough surface area, grout won't bond well and can fail prematurely, leaving room for leaks and water damage. It's also very important to let the adhesive cure fully.
In an older home, you may find the floor isn't square, which makes the job more complicated. Use the most obvious wall as a baseline, so those entering the room will see tile lines parallel to that wall; your job will look more even.
by Shirley C. Howard on Aug 01, 2018 Ceramic Tile