Finding hard, white crumbs between your bathroom floor tiles? That is probably damaged grout. If the tiles are firmly fixed, repairing the joints yourself can refresh the floor without the cost of replacing perfectly good tiles.
The key to saving money is checking the cause first. Regrouting can repair worn joints, but it will not fix loose tiles, a moving floor or a leak.
Is it grout or silicone?
Grout is the hard material between tiles. Silicone sealant is flexible and rubbery, usually found around a bath, shower tray and where surfaces meet.
This guide covers grout between bathroom floor tiles. Existing movement joints and perimeter joints that need flexible sealant should stay flexible—do not fill them with rigid grout.
Check your floor before buying anything
Gently step around the damaged area and check:
- Do any tiles rock or click?
- Are the tiles themselves cracked?
- Does the grout keep breaking in the same places?
- Is there damp on the ceiling below or around the floor?
If you notice these problems, have the cause checked before regrouting. Paying for new grout will be wasted money if movement or moisture causes it to fail again.
If the tiles feel solid and only a few joints are damaged, a small DIY repair may be suitable.
Money-saving tip: Repairing a patch can be cheaper than regrouting the whole floor, although new grout may look different from older grout.
What you need to buy
| Item | What it does | What to look for |
|---|---|---|
| Bathroom floor grout | Fills the joints between tiles | Suitable for your tile material, gap width and any underfloor heating |
| Manual grout rake | Removes damaged grout | A carbide blade narrow enough to fit between your tiles |
| Rubber grout float | Presses new grout into the gaps | A basic float suitable for floor tiles |
| Grouting sponge | Cleans excess grout from the tiles | A proper tiling sponge |
| Mixing container | Holds your grout mixture | A clean container |
| Measuring equipment | Helps you mix accurately | Suitable scales and a water measure |
| Protective equipment | Protects your hands, eyes and lungs | Follow the grout and tool instructions |
You will also need clean water, cloths, a soft brush and a vacuum suitable for the dust.
For a small repair, a manual grout rake is a sensible starting point. You may not need to buy a powered tool.
Which grout should you choose?
Mapei Ultracolor Plus is one option to compare for bathroom floor tiles. Check the current UK pack to confirm it suits your tiles and joint width.
If your existing grout is white, look at 100 White, but remember that different brands and older grout may have different shades.
This is a powder you mix with water. It sets quickly, so work in small batches and follow the instructions carefully.
Find the supplies on Amazon UK
These links open shopping searches. Compare pack sizes, delivery charges and seller details before buying.
Money-saving tip: Check local DIY shops and builders’ merchants too. A lower online price may become more expensive once delivery is added.
How much does DIY regrouting cost?
The total depends on the size of the repair, how much grout you need and which tools you already own.
Before ordering, add together the cost of:
- Grout.
- Grout rake.
- Float and sponge.
- Any protective equipment.
- Delivery.
Avoid buying a large bag simply because it costs less per kilogram. A smaller bag may cost less overall if most of the larger bag would go unused.
For widespread damage, compare the materials and your time with a tiler’s quote. Ask whether their price includes removing the old grout, checking loose tiles, materials and clearing up.
How to repair bathroom floor grout
1. Prepare the area
Clean away surface dirt, soap and grease. Let the floor dry as required by your chosen grout.
Keep children and pets away while you work, and plan how you will avoid using the floor during curing.
If you have underfloor heating, follow the grout and heating-system instructions for switching it off and restarting it.
2. Remove the damaged grout
Use the grout rake carefully along the affected joints. Remove loose and crumbling material without chipping the tile edges.
Do not simply spread a thin layer of new grout over the damaged surface. The replacement needs enough depth to form a proper joint.
Follow the preparation depth specified by your chosen manufacturer. Mapei’s Ultracolor Plus technical sheet, for example, specifies joints emptied to at least two-thirds of the tile thickness. Other manufacturers give different guidance.
Work slowly. Avoid cutting beneath the tiles, where waterproofing or heating components may be present. Stop if you cannot remove the grout safely.
3. Clean out the gaps
Remove the debris and dust thoroughly using a soft brush and suitable vacuum.
The joints need to be clean and free of loose material. Follow the grout instructions for any further preparation, and do not leave standing water in the gaps.
4. Mix a small batch
Measure the powder and water accurately using the ratio on the pack.
Avoid adding extra water to make the grout easier to spread. Do not add water to a batch that has started to stiffen.
Mix only what you can apply and clean within the stated working time.
Money-saving tip: Start with a small batch while you learn the process. This reduces waste if the grout sets faster than you expect.
5. Press the grout into the joints
Use a rubber grout float to push the mixture firmly into the gaps, working diagonally across them.
Fill the joints fully, then use the float to remove excess grout from the tile faces.
Keep grout out of movement joints and perimeter gaps that require flexible sealant.
6. Wipe away the excess
Wait for the cleaning time stated in the instructions, then wipe diagonally across the joints with a well-wrung grouting sponge.
Rinse the sponge regularly and avoid flooding the floor. Too much water or repeated wiping can disturb fresh grout.
Do not leave thick residue on the tiles until it hardens. Test your method in an inconspicuous area first, especially with textured, porous or delicate tiles.
7. Leave it to cure
Follow the pack instructions before walking on the floor, getting it wet or cleaning it.
Ready for light foot traffic does not necessarily mean ready for shower water or normal use.
Once permitted, remove remaining light haze with a clean cloth. Use only cleaners suitable for both the tiles and grout.
Check whether your particular grout needs a sealer before buying one.
Five mistakes that can cost you money
1. Regrouting loose tiles
New grout will not hold a moving floor together. Fix the underlying problem first.
2. Buying a grout pen for missing grout
Grout pens and colour refreshers can improve the appearance of stained joints. They cannot replace material that has crumbled away.
3. Choosing the wrong product
Check that your grout is suitable for floors, your tile material and the width of the joints. Do not assume a wall-only product or combined adhesive and grout will suit the job.
4. Leaving weak grout underneath
A repair needs sound preparation. Covering loose material is likely to produce another weak joint.
5. Rushing the mixing and curing
Extra water, oversized batches and using the floor too soon can spoil an otherwise careful repair.
Frequently asked questions
Can I put new grout over old grout?
Do not simply skim over damaged grout. Remove enough old material to meet the replacement product’s preparation requirements, then clean the joints thoroughly.
Do I need to regrout the whole bathroom floor?
Not necessarily. A local repair may be enough if the surrounding grout and tiles are sound.
If damage is widespread or keeps returning, get the floor checked before deciding how much to replace.
Will new white grout match the old grout?
It may not match exactly. White shades vary between brands, and existing grout changes with age and cleaning.
Test a small area and assess it once dry before tackling a larger patch.
Is bathroom grout waterproof?
Do not rely on grout alone to waterproof a shower or wet room. Even water-repellent grout does not replace a correctly installed waterproofing system beneath the tiles.
Should I use silicone between all the floor tiles?
Use suitable tile grout for ordinary tile joints. Silicone or another appropriate flexible sealant belongs in joints designed to accommodate movement.
When should I call a tiler?
Get help if tiles move, the floor feels soft, cracks keep returning, leaks are suspected or removing the old grout risks damaging the floor beneath.
The Money Saving Assistant verdict
A small grout repair can be a worthwhile DIY saving when the tiles are firmly fixed and the damage is limited.
Buy only what you need, spend time preparing the joints properly and follow the instructions for your exact product. Careful preparation matters more than an expensive toolkit.
Sources: Mapei Ultracolor Plus technical guidance and ARDEX regrouting preparation guidance. Always follow the current instructions supplied with the product you buy.