How big should my tile grout joint be?

How big should my tile grout joint be?

I have been asked this question time and time again, in many various forms:

"How wide should my grout lines be?"

"What size tile spacers should I use?"


"How much space should I leave between the tiles?"

The answer is pretty much always the same: "Smaller is better!"

The reason why the fashion has been going towards smaller grout joints is simple - Tiles have been getting larger and larger in the last decade. Customers are opting for a more seamless and continuous look. In the past tiles were traditionally much smaller. They looked busy with a small or large joint so it didn't really matter too much. These days people are choosing to tile their entire ground floor for example to give a continuous and unified look (usually in strong porcelain tiles), this in turn requires a small grout joint to make it look seamless. A large grout joint could break this up and make it look busier.

But of course, there are some other factors to consider:

1. Are the tiles rectified or not?

If the tiles are rectified which means they have a dead cut square edge, they can be really butted-up close to each other. This means a smaller grout joint of 1-3mm would be recommended. If the tiles aren't rectified you might need some extra space to play with as the edges might not always perfectly line up. In this case 3 or 4 mm might be better.

2. Are they wall or floor tiles?

Firstly we need to differentiate between wall and floor tiles. It's usually better to use a slightly larger grout joint on the floor compared to the wall. For example if you would like a small joint and you have rectified tiles and you are using 1mm on the wall, it might be a good idea to use 2mm on the floor. This is because floor areas will have some movement (unless they are on a solid concrete base) and to allow for this movement we need to have a bit more space between the tiles. The wall won't have any movement so you are free to use as small a grout joint as you wish. Many customers have asked if they can have no grout joint at all and butt them up as they would like a truly seamless look. What I usually tell them is even though this may look nice, if the tiles aren't grouted in properly and water gets behind them you are creating yourself a hell of a repair job. It would be better to have a 1mm joint in this case, grout it in nicely and have a secure finished job without the worry in the back of our mind.

3. How big are the tiles?

Traditionally grout joints used to get larger with the size of the tiles. The bigger the tile, the bigger the grout joint used to be. But as I mentioned earlier, over the last few years the fashion has been to achieve a seamless and continuous look, so these days whatever the size of the tile a small grout joint is preferred (1-3mm).

Although if you are using XL tiles such as 80x80cm and above, then a 1mm grout joint could be too small even if they are rectified (which they should be at that size). In XL size tiles I would recommend 2-3mm gap as minimum.

4. How much movement is there on the floor?

If you are tiling onto a wooden floor which has some movement you would be better off with a large joint of 3-5mm. This is to allow for any movement and hence break-up of the grout. If you have a small joint a gap could appear over time due to the movement and water could seep through. (Don't forget to use flexible adhesive and grout on wooden floors)

5. What if I'm tiling a wet room?

If you need to give some direction to the tiles such as a slant towards the drain in a wet room, then a large joint of 4-6mm would be beneficial. This would make your work easier as you can achieve the angles needed with the tiles in a quicker and more practical way.

6. What if my tiles have a wobbly edge?

Some tiles (usually kitchen wall tiles) can have a curvy or wobbly edge. With these types of tiles a large grout joint of 3-6mm would be the right choice. If you use small spacers the curvy edges of the tiles could touch, this would ruin the effect and would create an unattractive finish.

7. What colour grout should I use?

This really depends on the colour of the tile but usually a light colour grout is recommended unless the tiles are very dark. On the wall white grout is usually the most popular but, on the floor even if you have white tiles it would make more sense to go for a light grey or ivory as floor grout discolours and gets dirty over the years. If you use a brilliant white grout on the floor you will find after a year or so it may not be so brilliant any more. For dark floor tiles such as black or dark grey a black or charcoal colour grout would be recommended.