Green Mold On Concrete Patios: Causes And Prevention Tips

Green mold on concrete patios is not only unsightly, but it can also be a health hazard. Concrete is susceptible to mold growth because it retains moisture and provides a cool environment for spores to thrive. Green mold can cause staining, corrosion, and deterioration of the concrete surface if left untreated. To prevent and remove green mold, regular maintenance is crucial. This includes routine cleaning, improving drainage, and increasing sunlight exposure to create an environment that is inhospitable to mold growth. In addition to preventative measures, there are several methods for removing green mold, such as pressure washing, commercial cleaners, and DIY cleaning solutions.

Concrete is a habitable environment for mould

Concrete surfaces, such as patios, driveways, and paths, are prone to mould growth, which often appears as a green hue. This growth is typically due to the presence of algae, mould, or mildew, which thrive in damp, shaded areas. Factors such as poor drainage, lack of sunlight, and high humidity contribute to mould growth on concrete. Standing water, in particular, provides ideal conditions for mould to grow.

To prevent mould growth on concrete, regular maintenance is crucial. This includes routine cleaning and inspections to catch early signs of mould. Removing debris and standing water can help prevent the conditions that mould needs to grow. Sealing concrete with an exterior acrylic sealer can also help create a barrier against mould. However, sealants wear off over time and require reapplication.

If mould is already present on concrete, there are several removal methods available. One common method is to use a household bleach solution, mixing one cup of bleach with one gallon of water. This solution can be sprayed onto the concrete and scrubbed, effectively removing most of the mould. Another approach is to use a vinegar and water solution, which is less aggressive but still effective in removing mould. After mould removal, it is important to use a penetrating concrete sealer to prevent mould growth in the future.

Health concerns of exposure to green mould

Green mould is a generic term for various species of fungi that have a greenish colour. It can be found anywhere there is moisture and organic material, and it can cause serious health complications in humans and animals. Exposure to green mould can lead to "mould sickness", which is characterised by respiratory problems, especially in those with weakened immune systems or allergies.

The health risks associated with green mould exposure range from mild allergic reactions to more severe, long-lasting conditions. Prolonged exposure is hazardous and could aggravate chronic respiratory problems or even result in toxic health effects, particularly in susceptible individuals.

One of the primary concerns with green mould is its ability to emit mycotoxins, which are toxic to both people and pets. Exposure to these mycotoxins can lead to a range of health issues, including respiratory problems, allergic reactions, and, in severe cases, neurological damage. Certain types of green mould, such as Aspergillus, can infect the skin and even the brain. Some strains of Aspergillus are also toxic, allergenic, and carcinogenic, and can contaminate food, causing pneumonia, neonatal infections, and other health issues.

Even on outdoor surfaces like a concrete patio, mould can be harmful to those who are allergic. Therefore, it is important to address mould concerns promptly and seek professional help if needed.

How to remove mould from concrete

Mould on concrete can be unsightly and can become a health and safety issue. Concrete is a great incubator for mould due to its cool temperature and ability to retain moisture. It is important to address mould at the first sign of trouble to prevent it from spreading and causing lasting damage to surfaces.

Pressure Washer

For small, non-toxic infestations, using a pressure washer can be an effective way to remove mould from concrete. Simply power wash the area to remove any visible signs of mould. However, it is important to note that this method will not kill the mould spores, so it is likely that the mould will return. Therefore, this method should be followed up with a mould prevention technique.

Bleach and Power Wash

For a more aggressive approach, you can saturate the area with a bleach solution (1 cup of bleach to 1 gallon of water) and let it sit for 1-3 hours to kill the mould. Then, use a power washer to remove all mould debris. Bleach is known to kill mould on contact, but it can be corrosive to finished concrete and harmful if inhaled.

Vinegar

For a more natural solution, vinegar can be used to kill mould on concrete. Create a solution of 1 cup of vinegar to 1 gallon of water and spray it onto the surface, fully saturating the mould. Let the solution sit for 30 minutes, then spray again and gently scrub the area with a sponge. Repeat this process until all mould is removed. Vinegar is non-toxic and safe for skin and lungs, but it may corrode coloured concrete finishes.

Ammonia

Ammonia is a highly effective chemical against mould. It kills mould on contact and forces it to release from the surface. However, it is incredibly toxic to breathe, so it should not be used around children or pets. After applying an ammonia solution, simply wash it away with a hose or power washer.

Simple Green Solution

For concrete patios near landscaping, sewn grass, or gardens, a Simple Green Solution is a good option. This natural and safe solution can be sprayed onto the surface and washed away with a garden hose or wet sponge. While it doesn't kill mould, it forces the mould to release from the surface so it can be washed away.

Preventing Future Mould Growth

To prevent mould from returning, it is important to seal the concrete with a good-quality acrylic sealer designed for exterior use. Let the concrete dry for at least 2-3 days in rain-free, sunny conditions before sealing. You can also prevent mould by improving ventilation and drainage in the area, as well as keeping the concrete clean and free of dirt and moisture.

Natural solutions to prevent mould

Mould on concrete patios can be harmful to those who are allergic and can cause lasting damage to surfaces. Concrete is a great incubator for mould due to its cool temperature and ability to retain moisture. Here are some natural solutions to prevent mould from growing on your concrete patio:

Remove Sources of Shade

As mould thrives in shady areas, removing sources of shade can help deter mould growth. Trimming branches and other sources of shade can help prevent mould from growing.

Increase Ventilation

Mould often develops in areas with poor ventilation, such as carports, garages, and patios under decking structures. Investing in an outdoor dehumidifier can help prevent moisture build-up and reduce the likelihood of mould growth.

Repair Grading and Water Drainage

If you notice standing water or water flowing towards the area where mould is growing, you may have grading issues. Even after cleaning the mould, it will quickly return if the water drainage issue is not addressed.

Keep the Patio Clean

Maintaining a clean patio can go a long way in preventing mould growth. Sweeping and hosing off the patio regularly will prevent dirt and moisture from accumulating, creating an unfavourable environment for mould.

Seal the Concrete

Sealing the concrete with an exterior acrylic sealer can help prevent mould growth. Allow the concrete to dry for a few days in rain-free, sunny conditions before applying the sealer.

When to call a professional

If you have spotted green mold on your concrete patio, it is important to act quickly to prevent lasting damage to your property and potential health issues. While small amounts of mold can usually be removed by homeowners using household products, there are several situations in which you should call a professional for mold removal.

Firstly, if the mold covers an area bigger than 10 sq. ft. or has spread to another part of your home, professional help is recommended. Mold remediation specialists are trained to handle any type and amount of mold and can create an action plan to effectively eliminate it. They can also provide guidance on improving ventilation and preventing future mold growth.

Secondly, if you suspect the mold may be toxic, it is crucial to call a professional. Exposure to certain types of toxic mold can be extremely harmful or even fatal. Professionals can test the mold to determine its toxicity and safely remove it to protect your health.

Thirdly, if you have tried to remove the mold yourself but it keeps coming back, it is time to seek professional help. This could indicate underlying moisture issues or structural problems that a specialist can identify and address. They can track the source of moisture and fix the issue to prevent future mold growth.

Finally, if you have experienced water damage due to flooding, leaks, or other issues, it is advisable to call a mold remediation specialist. Water damage creates the ideal environment for mold growth, and specialists trained in water damage restoration can address both issues effectively.

While it may seem costly, hiring a professional for mold removal can save you money in the long run by preventing further damage and potential health problems. They have the expertise and equipment to handle any mold situation and can provide peace of mind that the job is done properly.

Frequently asked questions