A dark joint is not always a leak. Crumbling grout or recurring mould calls for inspection of the cause before a colour refresh.
Find the cause
Distinguish surface staining, failed grout and persistent moisture from a leak. Regrouting will not fix moving tiles or water behind the wall. Have the tiler check the tile and substrate.
Remove and refill
Old grout should be removed carefully without chipping tile edges. Clean and dry joints before applying a compatible product. Corners and bath junctions need flexible sealant rather than rigid cement grout.
Accept the work
Itemise the area, grout type, silicone replacement and mould treatment. Check even fill and no residue on the tile face. Water exposure and cleaning times depend on the product instructions.
Describe the job
- Area and length of failing joints.
- Photos of mould, cracks and loose tiles.
- Tile material, especially natural stone.
- Silicone replacement at bath or shower edges.
Frequently asked
Can fresh grout be applied over old grout?
A thin layer over dirty or weak grout is unreliable. Removal depth should follow the chosen product guidance.
Will regrouting stop a leak?
Only if the particular joint was the cause. Failed waterproofing needs a different repair.
How should natural stone be cleaned afterward?
Use a cleaner compatible with that stone and test a small hidden area. Acidic products can damage some stone.