I actually get a load of traffic to my blog with this very question (welcome to my blog which you found by typing that very question). A lugged tile is simply a tile that is self-spacing.
Lugged tiles are most commonly found in the form of 4 x 4 inch or 6 x 6 inch wall tiles commonly used in bathtub surrounds, small showers, and kitchen backsplashes (normally by builders). Standard tiled bathtubs normally use lugged tiles.
Each tile has two or three little ‘nubs’ on each side of the tile which, when stacked upon one another, keep the tiles a consistent distance apart. You can see the lugs in the photo above (click on it for a full-size version). The nubs of the tile actually stack on top of each other to create a nice, even grout line. With the standard lugged tile this grout line is just a bit under 1/16″.
I constantly reiterate the need for a tile installation to be flat. Not necessarily level, but always flat. This is the mark of a true professional and the thing that turns an ‘okay’ installation into a spectacular installation. (Did I just type ‘spectacular? Jesus…) Anyway, the method I use on floor tile to get it flat is fairly simple and ensures that each tile is the exact same height as the tiles surrounding it.
Before I show you that you need to understand, as always, that the substrate preparation is the most important aspect of this. If your tile substrate looks like a skate park you’re never going to get a flat tile installation over the top of it. Your substrate needs to be as flat as you can possibly get it. Take time with your preparation – it makes the rest of the installation run smoothly and gives you a solid foundation.