How to regrout tiles

Even the most beautiful tiles can look unsightly if the grout is cracking, falling out or become discoloured over time with dirt and grime. Regrouting can bring a room back to life without the need to replace the tiles.

As most tile grouts are cementitious, this means it is a porous material that is susceptible to liquid seeping in (even with a grout suitable for swimming pools). In addition to deep-set stains, water and other liquids can cause grout to deteriorate over time and may also lead to mould and mildew in between the grout cracking.

Ensure you wear a face mask as it’s a messy, dusty job. If you’re regrouting a bathroom or kitchen splashback put the plugs in the basin or bath to stop dust and debris from blocking your drains.

The grout should be dug out a minimum of 3mm deep (preferably deeper) so that new grout can have a firm base and a larger surface area of the sides of the tiles to adhere to.

Do not attempt to apply new grout over the damaged existing grout. Just applying new grout over the existing grout is called skim coating grout and the new grout will not properly adhere to the old grout. Over time the new grout will start flaking and chipping away.

There are two ways to effectively remove old grout…

The most cost-effective way is to use a grout rake but it can be quite labour intensive and take time. It is advisable to have a couple of spare blades, especially if you have a large area you want to re-grout.

Simply place the grout rake in the joint and move the rake up and down along the grout line whilst applying firm pressure to the joint. You will soon see the grout begin to powder and drop, remember grout can be tough so this takes time.

Be careful not to rush, one slip could lead to damage to the edge or surface of the tiles. Ensure all your grout lines are clean and free from debris and dust, also make sure there’s no excess adhesive residue by removing with a damp sponge.

he most effective way to remove grout is by using an oscillating tool such as the Fein multimaster, along with a segmented tungsten carbide grout removal saw blade.

Work the blade straight into the grout joint between two tiles. Avoid using too much pressure when working the blade into the joints, apply gentle pressure and let the tool do most of the work.

With most of the grout removed using that straight cut, you can now slowly move the blade up and down to remove more of the grout from the seam. Work slowly and carefully to avoiding damaging the edges of the tiles.

You may need to use a grout rake to scrape out any bits of material that would not come out with the power tool. Ensure all your grout lines are clean and free from debris and dust and there’s no excess adhesive residue by removing with a damp sponge 

When grouting tiles, you should make the same considerations when choosing your grout as you do when choosing your adhesive. For example, if you are tiling a power shower ensure the grout is suitable for that area and not just for swimming pools.

Make sure to add the powder to the water in your mixing bucket and not the other way around, this will ensure a lump free consistency once mixed. If you’re using an admixture, add it to your water and mix thoroughly before adding any grout powder.

Always mix to the instructions on the bag, different grouts require differing quantities of water. Bear in mind not to mix too much at one time as it will harden quickly creating wastage.

It’s important to mix at a slow speed, whether you’re using a bucket trowel or an electric mixer (keep it under 300rpm), until a smooth and lump free consistency is achieved. Don’t over mix it or mix too fast otherwise you’ll trap air in the mixture. Allow the mixture to stand for 2-3 minutes and then remix slowly for 30 seconds.