TL;DR
If the grout is discolored but solid, clean and seal it. If it is cracked, powdery, missing, or comes away when you scrape it, regrout. The deciding test takes about a minute: press a plastic pick into several joints and see whether material crumbles out.
The Two Problems Look the Same From Across the Room
A cleaning problem is staining. The grout is intact and structurally fine; soap film, body oils, mineral content, and mildew have soaked into the pores and changed the color. This is by far the more common case.
A repair problem is material failure. The grout has cracked, crumbled, washed out, or was never fully packed into the joint. No amount of cleaning restores missing material.
Getting this wrong is expensive both ways. People pay for regrouting when a clean and seal would have worked, and people scrub for months at joints that needed replacing.
The Tests That Decide It
Run all four. They take five minutes.
The scrape test. Drag a plastic pick along several grout lines with light pressure. Solid grout resists. Failing grout gives up sand and powder.
The depth test. Look at the joint from an angle. Grout should sit close to flush with the tile face. A deep valley means material has washed out.
The tap test. Tap the tile face with a knuckle. A crisp sound means the tile is bonded; a hollow sound means it is loose, which is a bigger problem than grout.
The movement test. Press on tiles near the failing joints. Any flex means the substrate has a problem, and that is a job for a tile professional.
Reading the Result
| What you find | What it means | What to do |
|---|---|---|
| Discolored, solid, flush | Staining only | Clean and seal |
| Discolored, slightly low, solid | Normal wear plus staining | Clean and seal |
| Powdery, crumbling, sand coming out | Grout failure | Regrout the affected area |
| Missing sections, visible gaps | Grout failure | Regrout |
| Cracks at inside corners and the tub joint | Wrong material used | Caulk, not grout |
| Hollow sound, tiles moving | Bond or substrate failure | Tile professional |
That fifth row catches a lot of people. Inside corners and the joint where the wall meets the tub or pan are movement joints. Rigid cement grout cracks there because the surfaces move independently. The correct material is a flexible sealant, so cracking there is not a grouting failure at all. See when shower caulk must be replaced.
If It Is a Cleaning Job
Cleaning is dramatically cheaper and easier than regrouting, and most people underestimate how much of the original color it recovers when done properly.
The short version: degrease first, then an oxygen bleach paste on the grout lines with a 15 to 30 minute dwell, agitated with a stiff nylon brush and rinsed twice. The mistake almost everyone makes is scrubbing hard for two minutes instead of letting a paste sit for twenty. Full steps are in the full grout cleaning method, and why absorbed soil resists scrubbing is explained in why shower grout turns dark. Then seal it, or you will repeat this in months rather than years, as covered in whether sealing grout helps.
Safety note: never mix chlorine bleach with an acid such as vinegar or a hard water remover, and never with an ammonia-based glass cleaner. Both produce toxic gases in a small room. Use one product at a time and rinse in between.
If It Is a Regrouting Job
Regrouting means removing the old material and installing new. It does not mean smearing new grout over old, which fails within months because the thin new layer has nothing to bond to.
The process, in outline:
- Remove old grout to at least two thirds of the joint depth, using a grout saw or an oscillating tool with a grout blade.
- Vacuum out every trace of dust. New grout does not bond to dust.
- Pack new grout into the joints with a rubber float held at an angle, working diagonally.
- Wipe the tile faces with a damp sponge, rinsing constantly, before the grout sets.
- Buff off the haze once it dries.
- Wait the full cure time, often 48 to 72 hours, then seal.
Removal is the hard part: slow, dusty, and easy to chip tile edges with a power tool. Wear eye protection and a dust mask, and go slower than feels necessary.
Partial Versus Full Regrouting
You do not have to do the whole shower. If failure is confined to the bottom rows and the corners, regrouting only those areas is legitimate, though expect a slight color difference since new grout rarely matches aged grout. Failure scattered across the whole installation usually points to an installation problem or water behind the tile, and doing it all at once makes more sense.
What Each Option Costs
Industry Baseline Range
| Option | Typical range |
|---|---|
| DIY cleaning supplies and sealer | $25 to $75 |
| Professional grout cleaning and sealing, per square foot | $1.00 to $4.00 |
| DIY regrouting materials and tool rental | $60 to $250 |
| Professional regrouting, per square foot | $5.00 to $25.00 |
| Professional color sealing to change grout color | $2.00 to $6.00 per square foot |
These figures reflect published industry averages. Current market pricing varies significantly and actual quotes may fall well outside these ranges based on site-specific conditions, material costs, and project complexity.
Current Market Reality
Regrouting pricing is driven by removal labor, which varies enormously with joint width, grout hardness, and how tight the tile spacing is. Small bathrooms usually carry a minimum charge that makes per-square-foot figures misleading. If loose tile or a substrate issue turns up mid-job, the scope changes to tile work and the number changes with it. Nobody can quote this responsibly without seeing it.
For context on the whole category of work, see the complete tile and grout guide.
The Honest Decision Rule
Clean first, in almost every case. It is cheap, reversible, and it tells you what you actually have. Plenty of grout that looked like it needed replacing turns out to be intact under two years of soap film. Regrout when material is missing or failing, when a proper cleaning still leaves color you cannot accept, or when you are already renovating the room.
FAQ
How do I know if I need to regrout or just clean?
Scrape a plastic pick along several grout lines. If the grout is solid and only discolored, cleaning and sealing will fix it. If sand or powder comes out, or if you see gaps and missing sections, the material has failed and needs replacing.
Can you put new grout over old grout?
No, not successfully. New grout applied as a thin skim has no depth and nothing to bond to, so it cracks and flakes within months. The old material must be removed to at least two thirds of the joint depth before new grout goes in.
Why does grout crack in the corners of my shower?
Because corners and the tub or pan joint are movement joints, and rigid cement grout cannot flex. Those locations should be filled with a flexible sealant rather than grout. Cracking there is a materials mismatch, not a sign that the grout has failed.
Will cleaning make old grout look new again?
Often much closer than people expect, if the grout is intact. Degreasing followed by an oxygen bleach paste with a long dwell removes years of absorbed soap film. It will not restore grout that has physically eroded, and it will not change grout that was dyed by a previous stain.
Is regrouting a DIY job?
The installation is manageable. The removal is the hard part, since it is slow, dusty, and easy to chip tile with a power tool. A small area is a reasonable weekend project with eye protection and patience. A whole shower is a long job most people are happier hiring out.
When the whole house is the problem rather than one task, recurring house cleaning services are the wider option.
Once you know which job it is, the next question is scope. Every home is different, so the real number depends on size, condition, and what you want covered. Get a quote and we will walk you through it.