Can mold grow through grout?

Author: Delores Stokes  |  Last update: Wednesday, June 25, 2025

Your tile is a non-porous surface that is hard for mold to cling to. Your grout, however, has the perfect texture for moisture to get stuck and for mold to grow. You can make it more challenging for mold to grow and for other stains to pop up in your grout by sealing it.

How do you know if you have mold behind tile?

A persistent damp or musty smell in your bathroom, even after cleaning, could be a sign of mold hiding behind your tiles. Discoloration, like dark spots or stains around grout lines or on the tiles themselves, may indicate mold growth beneath the surface.

How do you get black mold out of shower grout?

Bleach is the most effective method for removing mold from shower grout. Method One: Make a solution of one-part bleach and four-parts water, and put it in a spray bottle. Spray the affected area and scrub with a brush after 30 minutes. Rinse with water and repeat if necessary.

How do you tell the difference between mold and mildew in shower grout?

So how do you know which one you're dealing with? Mold generally looks slimy or fuzzy, tends to have a raised texture, and can come in a rainbow of colors, including deep green and black. Mildew is powdery, looks white or gray, always appears flat, and grows on surfaces.

What is the black stuff on my tile grout?

Black grout can also be mold and mildew, which forms where there's moisture or high humidity. Mold is a type of fungus. Unsurprisingly, it's not good for your health.

Pro Advice: Why does Mold Grow on Tile?

Can you use bleach on black grout?

No Bleach Allowed

Bleach may cause the color of the grout to fade. The uneven appearance makes the grout look old and worn.

How do professionals clean grout?

Steam cleaning is one of the most powerful ways to clean grout without the use of harsh chemicals. Professionals often use steam to loosen the dirt and other particles trapped in the grout without needing to scrub manually.

Does sealing grout stop mold?

Grout sealer can help prevent mold growth to some extent by reducing the porosity of the grout and making it less susceptible to moisture absorption.

What does harmless black mold look like?

Although the name implies a uniform coloring, black mold may appear black, dark green, or dark brown. It typically grows as a cluster of round spots with a distinctly wet, slimy appearance. As stated, black mold typically appears fuzzy or furry.

How often should I regrout my shower?

The best time to regrout shower and bathroom tiles is when you see mold, grout color changes, or the grout is old, about 15-20 years. Showers need more frequent regrouting because they're wet. Seeing mold or mildew between tiles means it's time for new grout.

Is vinegar or bleach better for killing mold?

Vinegar is better at killing mold because it can work on both porous and nonporous surfaces. It also terminates molds at their roots so the mold won't return and is also safer than bleach. You can even combine it with baking soda to make it more effective.

Does hydrogen peroxide damage grout?

Yes, hydrogen peroxide is a natural neutral cleaner that is safe to use on grout. Hydrogen peroxide and baking soda produce oxygenated bleach, which is highly effective for cleaning grout.

What is the best mold remover for grout?

Opt for household staples like borax, ammonia, baking soda paste, or commercial grout cleaners. The vigorous scrubbing action helps dislodge the mold on grout.

How to get rid of mold behind grout?

Bleach is the most effective method for removing mold from shower grout. Method One: Make a solution of one-part bleach and four-parts water, and put it in a spray bottle. Spray the affected area and scrub with a brush after 30 minutes. Rinse with water and repeat if necessary.

What to do if you smell mold but can't find it?

When a homeowner smells mold but visual clues are invisible to the naked eye, then mold testing can be performed by a professional to locate the colonies. A mold testing kit can also be inexpensively purchased from the local hardware store and utilized by the homeowner.

How do you tell if mold is growing behind walls?

How to Detect Mold in Walls
  1. Water stains.
  2. Dark rings.
  3. Discoloration.
  4. Deterioration like peeling, bubbling, or cracking of the paint or wallpaper.

What are signs of mold sickness?

Although symptoms can vary, the most common symptoms seen in people exposed to mold indoors include:
  • Nasal and sinus congestion.
  • Eye irritation, such as itchy, red, watery eyes.
  • Wheezing and difficulty breathing.
  • Cough.
  • Throat irritation.
  • Skin irritation, such as a rash.
  • Headache.

Is it safe to live in a house with black mold?

Black mold can cause health problems. As such, it is not advisable to be in a house with black mold. If a person must stay in a house with black mold, they should try to seal off any areas where black mold is present to reduce contact with it.

What can be mistaken for black mold?

Aureobasidium

This yeast-type fungus can be mistaken for another more sinister and dangerous mold but is far less likely to make you sick. Aureobasidium can start as a slimy pink color, but it will turn brown or black and can look like black mold.

Can mold grow behind grout?

Grout and tiling can create perfect little environments, or breeding grounds, for mold. As harmless as it may seem, ignoring the mold that darkens the lines of grout between your tiles is a bad idea. Mold, particularly the dreaded black mold, is a type of fungus that thrives in moist, warm environments.

What is the best product for moldy grout?

LTP Grout Stain Remover is a powerful solution for tackling stubborn stains and mould on grout. It's particularly effective on cement-based grouts, which are commonly found in homes and more domestic settings.

How often should I reseal grout?

For high-traffic areas, like the main bathroom, you should consider sealing it every six months, while low-traffic areas like the guest bathroom can be resealed every two years. If you are using epoxy grout, it might not be necessary to reseal it as it is highly water-resistant.

What should you not use to clean grout?

Chemical cleaners, such as, Tilex, Soft Scrub, Scrubbing Bubbles, or ammonia products will nearly always result in your tile surfaces' grout becoming very discolored.

How often should grout be professionally cleaned?

While it's possible to do a fairly thorough cleaning by hand, professionals have the tools to clean tile and grout more thoroughly than tools at home allow, and it's recommended that you schedule a professional cleaning about once every 9-12 months or so.

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