Shower Mold


Every week we get calls asking what to do about mold found in the shower. You know the type, small dots on the paint that slowly but surely increase in number and size, slime that accumulates along caulking; and unsightly, discolored grout.

While most of these situations are easily remedied, there are certain situations that can be indicators of bigger, more extensive problems. Below is a guideline on common mold growth situations found in the bathroom.

  1.  Dark spots: Usually found growing on the surface of painted materials, this is one of the most common areas of mold growth we come across. The threat to health and the physical home structure is minimal, and is usually a very simple cleanup.
    1. Causes of growth are usually dust and discarded skin cells that have settled on the affected surface. This is especially problematic in showers because we shed a large amount of skin cells here. Old skin cells make up a large percentage of household dust, with the typical person losing 30,000-40,000 skin cells every hour, and almost 1,000,000 every day. (How Stuff Works). When these skin cells settle, it provides the organic material that mold needs to grow; and combined with the humidity from the shower, creates a perfect growing environment.
    2. Treatment is usually easily accomplished with household cleaners, although it can become more difficult depending on how dirty the surface is or how long the mold has gone unattended. The homeowner’s best defense against shower mold is to consistently clean surfaces, run ventilation fans to keep humidity down, and treat affected areas as soon as mold appears.
  2. Caulk slime is caused very similarly, but is more difficult to treat because of the mold’s ability to grow deeper within the material. Mold still needs the organic material to grow, but when this organic material is lodged deeper in the caulking, the mold too will grow deeper. The cracks and imperfections that accumulate over time in caulking allow the same grime and skin cells from the situation above to settle in much harder to reach places.
    1. Treatment, unless mold is dealt with right away, usually involves tearing out and replacing old caulk. This eliminates the current mold problem as well as replacing the deteriorating caulk that could potentially lead to worse water intrusion problems down the road.
    2. Health affects are most likely very minimal, but the mold will contribute to continued deterioration of the caulk, which can lead to water getting behind the shower enclosure and leading to much more expensive problems.
  3. Grout mold is usually the most difficult to clean. If old or not properly sealed, grout has the same vulnerabilities as the deteriorating caulk, without the simple solution of remove and replace. Mold will slowly begin growing deep in the texture of the grout surface and become increasingly harder to remove.
    1. Treatment is usually best done by professional cleaning companies who are able to use special tools to clean the grout and surrounding tiles. If caught soon enough, a simple household grout cleaner and an old toothbrush may be able to take care of it.
    2. Health affects, like the situations above, are again minimal; but mold will eventually lead to a faster deterioration of the grout.
  4. Mold growing on drywall is usually indicative of a bigger problem. Sometimes cracks or bubbling in paint can allow mold access to grow on the drywall beneath. The paper backing of most drywall materials is prime organic material for mold to grow on and can spread rapidly if not dealt with right away. Mold growing directly on the drywall can also indicate a water leak inside the wall that is contributing to an ever growing, unseen mold problem. If you suspect this is the case, it is best to call a professional to evaluate the situation.
    1. Treatment requires removal of all affected drywall. Drywall is a porous material and is not able to be effectively treated once contaminated with mold growth. Any wood that has been contaminated will need to be treated and cleaned. Once drywall is removed, new drywall can be installed.
    2. Health and structural damage risks are much higher in these situations, because the unseen mold growth can grow unchecked for long periods of time, releasing millions of spores into the air allowing it to cause damage to drywall, wood studs, flooring, etc.

Typically, mold in the bathroom is a simple problem that can be effectively dealt with by using preventive measures and some good household cleaners. It is essential that areas around the tub and shower are properly sealed and caulked to prevent water gaining access to the more vulnerable drywall and other surounding materials.

Remember to run shower fans, keep the surrounding areas clean, keep a sharp lookout for potential problems, and you’re well on your way to a clean, mold free bathroom.

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