The planning stage (often referred to as 'setting out') is probably the most overlooked aspect of tiling. Yet it's the thing that can really make or break a tiling project and mean the difference between a professional looking tiled area or something that resembles a schoolchild's collage.

Ensuring that there are no thin slivers at either end of a tiled area is the basic idea behind setting out tiles and the golden rule is that the tiles at the ends of the wall should never be less than a fifth of the total length of the tile. For example a 150mm standard ceramic tile shouldn't be thinner than 30mm (it's important to use mm when tiling and it's often referred to as a 'millimetre art').

One way to do this is to laboriously lay out the tiles in the area to be tiled to see how things will play out but with small tiles such as Victorian floor tiles, this is virtually impossible. This is fine if you've got a lot of time on your hands but while being incredibly tedious, it is also often inaccurate as the slightest knock can ruin all your work.

The smart way to set out tiles is using a simple formula and all you'll need to know to use it is the length of the wall you'll be tiling, the length of one of your tiles and the width of your grout lines.

Surprisingly, the most common mistake at this point is measuring the length of your tile as it needs to be millimetre perfect. If you're wrong by just 1mm at this point and you have to tile a wall that's 20 tiles long, then you're going to be out by a whopping 2cm at the other end. The most accurate way to measure a tile is by its back. You'll notice that ceramic tiles have curved edges on the top whereas the clay back of the tile is it's true size. Be sure to take a measurement at the edge rather than the middle of the tile so you know you've got a good, solid right angle. It's also worth measuring 3 or 4 of your tiles to get an average as there are often slight irregularities in tile batches.

A typical grout line width is 2mm and a typical tile size is 150mm by 150mm so that's what we'll use in our example. The formula goes as follows and our example will come after:

length of wall ÷ (length of tile + width of grout line) = a number

2914mm ÷ (150mm + 2mm) = 19.171

Now the first part of the number before the decimal point is the number of whole tiles you'll be able to fit into the wall. That's nice to know but it's the part after the decimal point that is important when it comes to setting out tiles. If it's below .20 (like in our example) then you'll end up with one of the tiles at the end being less than a fifth of the width of a whole tile which breaks the golden rule of setting out tiles. What you'll need to do here is start your wall with just over half a tile and it'll end with just over half a tile too.

If the end number is higher than .20 and you're starting your wall with a whole tile, then you don't need to worry (unless you're a perfectionist that is). It gets a bit complicated here but if you multiply your tile width by the decimal you got, you'll get the length of the leftover (cut) tile at the end. Now if you divide this by 2 and add it to half the width of your tile, then this is the length that your cut tiles need to be at either end of the wall for them to be exactly the same.

150mm x 0.36 = 54mm 54mm ÷ 2 = 27mm 27mm + 75mm = 102mm

While this isn't really essential on a long wall (over 10 tiles) where it won't show too badly, on a short wall that's around 3 tiles across, it's essential that the cut tiles at the edges are of the same length.

Now that you've learnt how to set out tiles, you'll never be able to look at them the same way again and every time you go to the bathroom at a restaurant, you'll find yourself working out whether they brought in a professional or tiled it themselves. This is the curse of tiling.

To get your tiles online from a well known company visit Topps Tiles or for a wider range try Walls and Floors. We have discount codes for Walls and Floors to save you money when you visit their site through iDoDIY.