Over time, the grout between your bathroom tiles can often discolour and erode, leaving you with black, broken lines running all up the walls. The problem is often worst wherever water collects, so you’ll probably notice it first on the areas around the bottom of showers, sinks, baths and windowsills.
Your first step should always be to try and give your grout lines a good cleaning – and a thorough scrub with the right mix of products will often work wonders for grubby looking grout. Sometimes, however, the damage is too far-gone and you’ll have to think about regrouting. If your grout is dirty, it can be cleaned – but if it has started to wear away and go lumpy, you need to dig it out and start again.
The process is a bit time-consuming and sometimes messy, but it’s not difficult to do and the results are well worth the effort – a freshly regrouted bathroom can look brand new when it’s done right, which isn’t bad for a few hours of work and a bit of elbow grease.
Step 1: Getting rid of the old grout
This is the messy bit. Digging out the old, dirty grout will cause a lot of debris and dust to fly around, so make sure you’re wearing old clothes, a good pair of gloves and some eye protection. It’s also a good idea to put a dust sheet down on the floor to catch all the loose bits.
You might be tempted to use an old screwdriver or spoon to scrape out the old grout, but you’re much better off using a proper grout rake to avoid scratching the tiles. Work in one direction only, pushing the rake in between the tiles to dig out all the old grout, making sure you don’t miss any. If you don't like the idea of digging it all out manually, you can buy an electric grout grinder to do the job for you, but you will need to be extra careful not to scratch the tiles.
Step 2: Laying the new grout
Once you’re sure you’ve removed all the old grout, you can start putting the new grout in. Grout comes in a variety of different colours (even “glitter”), so decide if you want a freshening up or a whole new look before you buy.
If you’re using a powdered grout, mix it up in a bucket according to the packet instructions. If you buy ready-mixed grout, you’re ready to start. Again, it’s a good idea to get the right tool for the job here and a small tiling trowel will save you a lot of time and give you a much better finish than anything else you will find in your toolbox.
Push the grout into every crack, making sure you fill every line and corner without leaving any holes. Don’t worry about being a bit sloppy here – you can tidy it up afterwards.
Once the tiles are fully filled, use a damp cloth (or a finger) to smooth down the lines and compact the grout. If you notice any air pockets or holes, stick a bit more grout in and smooth it down again until you get a good finish.
Step 3: Cleaning up
When you’re happy with the grout lines, use a cold wet sponge to clean the whole wall. Be gentle around the lines themselves, but push harder on the tile surfaces to get rid of any excess grout that might have spilled over.
Wait for about half an hour, and then repeat the process again to make sure you’re cleaning off any surface haze on the tiles that might have started to set.
The drying time will vary from grout to grout, so read the instructions carefully to find out how long you need to keep the wall dry for. But if you’re regrouting a shower or bath area that’s likely to get very wet, it’s a good idea to wait at least 24 hours before soaking it, regardless of whatever the pack says.
Once the wall is fully dry, you might notice a dusty residue on the tiles that can usually be polished off with a dry, soft cloth and a bathroom spray. If you see any lumps of grout that have dried unevenly, gently smooth them with a bit of sandpaper before polishing up to a nice finish with a soft cloth.
If your walls need something a bit more drastic than a new grout job, read our guide to tiling your bathroom.