Short Answer
To repair shower grout, cut out the damaged grout, regrout the flat joints, and caulk the corners instead of grouting them. A full shower regrout costs about $1,500 on average nationally. In Houston, Repipe Solutions regrouts or recaulks showers for $250 to $850. If new grout keeps cracking, the problem is usually underneath the tile.
Repipe Solutions is a licensed Houston plumbing company, and cracked or missing shower grout is one of the most common things we are called out to look at. Sometimes a regrout is all a shower needs. Other times the grout is a symptom of something else. This guide explains why shower grout fails, how to repair it the right way, and when the grout is not the real problem.
Why Does Shower Grout Crack or Fall Out?
- Movement. Walls and floors expand and contract with moisture and temperature. True Value notes that grout often cracks because of moisture changes in the framing behind it. Grout is rigid, so it cracks instead of flexing.
- Grout in the corners. Corners and the joint where the wall meets the floor move the most. Grout placed there is the first to crack.
- Age. Fixr notes that most older grout eventually turns brittle and starts to crack.
- Harsh cleaners. Acid, ammonia, and bleach cleaners wear down cement grout. In Houston, where people scrub hard water scale often, this speeds things up.
- Poor mixing or application can leave grout weak and crumbly from the start.
- Something moving underneath. Lowe’s warns that if grout keeps chipping or cracking after a repair, the underlayment may be uneven or exposed to moisture.
Signs Your Shower Grout Needs Repair
- Cracks along grout lines, especially in corners and at the base of the walls
- Gaps where grout has crumbled out
- Black or pink staining that comes back right after cleaning
- Grout that stays dark long after the shower has dried
- Caulk that is peeling, split, or moldy
- Loose tiles or tiles that sound hollow when tapped
The last two signs on that list, dark grout that stays wet and loose tiles, can mean water has already gotten behind the tile. We cover those below.
Regrout or Recaulk? Where Caulk Belongs
This is the part most DIY guides skip. Grout goes in the flat joints between tiles. Anywhere two surfaces meet at an angle, or tile meets a different material, the joint should be filled with a flexible sealant, not grout.
A tile installer writing in JLC explains that guidance from the Tile Council of North America calls for caulk wherever walls and floors meet, because those surfaces move independently. Silicone, urethane, or multi-polymer sealants are recommended, and acrylic caulk is not suited to horizontal wet spots.
| Joint | Use |
|---|---|
| Flat joints between tiles | Grout |
| Inside corners | 100% silicone or urethane sealant |
| Wall to floor or wall to tub | Sealant |
| Around the valve trim, spout, and shower arm | Sealant |
| Where tile meets glass, stone, or a prefab base | Sealant |
So if the only cracks are in the corners, the shower may not need a regrout at all. Cut out the cracked corner grout and caulk it. Regrouting a corner just sets it up to crack again. FloorElf notes that silicone in the corners usually needs replacing every 5 to 7 years as normal upkeep.
Which Grout Is Best for a Shower?
| Grout Type | Needs Sealing? | Good to Know |
|---|---|---|
| Sanded cement | Yes | For joints wider than 1/8 inch. Can scratch glass, metal, and polished stone. |
| Unsanded cement | Yes | For joints 1/8 inch or narrower, and for tile that sand would scratch. |
| Epoxy | No | Very stain resistant, but harder to apply. |
| Urethane (premixed) | No | Comes ready to use. Cures slower in humid air. |
| Single-component (premixed) | No | Good for repairs, with no mixing. |
Sources: Lowe’s for the 1/8-inch rule, Custom Building Products for single-component grout, Laticrete for epoxy, and Bostik for urethane.
Houston humidity matters here. Bostik’s data sheet for its urethane grout says humidity affects curing more than temperature does, and high humidity slows it down. Whatever grout you use, follow the label’s cure time before using the shower, and expect it to take longer on a muggy day.
Epoxy is rigid too, so even with epoxy grout, the corners still get sealant.
Does Shower Grout Need to Be Sealed?
Cement grout does. Epoxy, urethane, and single-component grouts do not, according to their manufacturers.
Sealing is often misunderstood. A sealer slows water and stains from soaking in, but it does not make grout waterproof. A Ceramic Tile Education Foundation expert, writing in Floor Trends, notes that even good cement grout can absorb 7 to 15 percent water, and calls sealers more of a cleaning aid than waterproofing.
- When to seal: Custom Building Products’ sealer data sheet says sealer can go on 48 hours after grouting, usually in two coats.
- How to tell if it needs resealing: put a few drops of water on the grout. If they soak in, it is time for another coat. The same data sheet recommends checking every two years.
- How to keep it sealed: skip cleaners with acid, ammonia, or bleach.
How to Regrout a Shower
Regrouting is a manageable DIY project if you have patience. This Old House and Angi estimate 8 to 16 hours of work.
- Deal with any mold first. Clean and dry it before any new grout or caulk goes on (see the mold section below).
- Remove the old grout with a grout saw, carbide rake, or oscillating tool. Do not grout over old grout. Mr. Handyman warns it leads to uneven lines and mildew, and new grout cannot bond properly to old grout.
- Cut out the corner joints and plan to caulk them, not grout them.
- Vacuum the dust and let the joints dry completely. In a Houston bathroom, run the fan or a dehumidifier.
- Choose the grout based on joint width and tile type, using the table above.
- Pack the joints with a rubber float held at an angle, then wipe the haze with a damp sponge.
- Let it cure for the full time on the label before using the shower.
- Seal cement grout once it has cured, then caulk the corners and fixture trim with 100% silicone.
How Much Does Shower Grout Repair Cost?
| Option | Typical Cost | Source |
|---|---|---|
| DIY tools and materials | $100 – $200 | This Old House |
| Shower grout repair | $250 – $900 | Angi |
| Full shower regrout | $600 – $2,500 (about $1,500 average) | HomeAdvisor, This Old House |
| Recaulk add-on | $150 – $300 | Fixr |
| Repipe Solutions regrout or recaulk (Houston) | $250 – $850 | Our pricing |
The cost depends on the size of the shower, whether the floor and walls are both done, the grout type, and how hard the old grout is to remove. Epoxy costs more to install than cement grout. Angi notes that hard water and poor ventilation can shorten the time between regrouts, and both are common in Houston bathrooms.
When the Grout Is Not the Real Problem
Grout is the visible part of a tile shower, but the waterproofing is the membrane or pan liner behind and under it. New grout makes a shower look better, but it will not fix a failed pan or a leaking valve. Look past the grout if you notice:
- Grout that cracks again soon after a repair
- Tiles that are loose or sound hollow
- Grout around the drain that stays dark
- A soft or moving shower floor
- Stains on the ceiling below, or damp baseboards outside the shower
To narrow down where water is getting in, see our shower pan leaking guide, which covers the tests for grout, pan, drain, and valve leaks in order. The difference in cost is large: a regrout or recaulk runs $250 to $850 with us, while a shower pan leak rebuild runs $1,200 to $3,500. We confirm where the water is coming from before quoting either one.
Mold in Shower Grout: What to Do
- Small areas can be cleaned yourself. The EPA says most homeowners can handle mold covering less than about 10 square feet.
- Do not caulk or grout over mold. The EPA says to clean up mold and dry the surface before painting or caulking.
- Bleach is not the routine answer. The EPA does not recommend chlorine bleach as a routine practice for mold cleanup, and it should never be mixed with ammonia.
- Control the moisture. Run the fan during and after showers and keep indoor humidity below 60 percent.
- Mold that keeps coming back may mean moisture is coming from inside the wall, often from a leak.
Frequently Asked Questions
Can I put new grout over old grout?
No. New grout does not bond well to old grout and can crack or trap moisture. Remove the old grout first.
How often should a shower be regrouted?
Angi puts it at every 8 to 15 years. Hard water, poor ventilation, and harsh cleaners shorten that.
Should shower corners be grouted or caulked?
Caulked. Corners move, and rigid grout cracks there. Use 100% silicone or urethane sealant.
Is shower grout waterproof?
No, not even when sealed. The waterproof layer is the membrane or pan liner underneath the tile.
How long after regrouting can I shower?
It depends on the grout. Laticrete says its epoxy can be used in 48 to 72 hours at 70 degrees. Bostik’s urethane grout needs 3 days before water exposure, longer in high humidity. For cement grout, also allow time for sealing.
Can cracked grout cause a leak?
Yes. Water that gets through cracked grout can reach the wall and floor behind the tile. If the waterproofing behind it has failed, that water leaks out.
Need Shower Grout Repaired in Houston?
Repipe Solutions regrouts and recaulks showers across Greater Houston, and checks the pan, drain, and valve along the way. Quotes are free, in person, with no trip charge. See our shower pan and regrout services in Houston or contact Repipe Solutions to schedule a visit.
Featured photo: “Cracked grout between shower tiles” by phil_g via Openverse, licensed under CC BY-SA 2.0, converted to WebP and shared under the same license.