
If your concrete patio is looking a little green, it's probably due to algae, mould, or mildew. These organisms thrive in damp, shaded spots, and can quickly spread across concrete surfaces, creating an unsightly layer of green. Luckily, there are several ways to fix this issue and restore your patio to its former glory. This may involve some elbow grease, but the results will be worth it!
Characteristics | Values |
---|---|
Cause | Growth of algae, mould, moss, mildew, or lichens |
Location | Concrete patios, basement floors, and walls |
Appearance | Slimy, dark green layer or spots |
Hazards | Slippery surface, permanent discoloration |
Prevention | Sunlight exposure, improved drainage, landscaping, sealing |
Removal methods | Pressure washer, boiling water, bleach, vinegar, commercial products |
What You'll Learn
- Identify the cause: algae, mould, mildew or moss
- Natural solutions: sunlight, improved drainage, vinegar, bleach
- Commercial products: Wet & Forget, BioAdvanced 2-In-1 Moss and Algae Killer
- Pressure washing: correct nozzle, start at a distance, protect eyes
- Seal concrete: Joint-It Premium Seal, fluoropolymer barrier, reapply regularly
Identify the cause: algae, mould, mildew or moss
Before treating your concrete patio, it's important to identify the root cause of the green hue. The most common culprits are algae, mould, mildew, or moss. Each of these organisms has distinct characteristics that can help you determine which one is affecting your patio.
Algae often appear as a slimy, green layer on the surface of the concrete. It thrives in damp and shaded areas, and its growth can spread quickly, creating an unsightly layer on your patio. If left untreated, algae can make your patio slippery and hazardous.
Mould and mildew usually present as dark green or black spots on the concrete. They often grow in damp and humid conditions, particularly in areas with poor ventilation. Mould and mildew can have a fuzzy or slimy texture and can spread if not addressed promptly. They can also cause musty odours and potential health hazards.
Moss, on the other hand, tends to have a thicker and fuzzier texture than algae. It grows in shaded areas and requires moisture to thrive. Moss can quickly cover your patio, creating a soft and slippery surface.
To identify the cause, examine the appearance and texture of the green growth on your concrete patio. Check for sliminess, which indicates algae or mould/mildew, or a fuzzier texture, which suggests moss. Also, consider the environmental factors that promote the growth of these organisms, such as shade, moisture, and poor ventilation.
Once you have identified the specific organism affecting your patio, you can choose the most effective treatment method to remove it and prevent future growth.
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Natural solutions: sunlight, improved drainage, vinegar, bleach
The green hue on concrete patios is often due to the growth of algae, mould, or mildew. These organisms thrive in damp, shaded areas and can quickly spread across your concrete surfaces, creating an unsightly green layer. Here are some natural solutions to tackle this issue:
Sunlight
Sunlight is a natural deterrent for algae, mould, and mildew growth on concrete. These organisms thrive in damp, shaded areas. By increasing sunlight exposure, you can naturally inhibit their growth. Trimming back trees and shrubs can help increase sunlight exposure, keeping your concrete surfaces dry and less welcoming to algae.
Improved Drainage
Standing water encourages algae growth. By improving drainage, you can prevent water from accumulating on your concrete surfaces. Consider installing drainage channels or adjusting the slope of your land to direct water away from your concrete areas. These changes will help keep your patio dry and less prone to green growth.
Vinegar
You can make a DIY cleaning solution using household vinegar. Remember to dilute vinegar before use to prevent potential damage to your concrete. When applying the cleaning solution, ensure it covers the entire affected area and let it sit for a while to break down the algae.
Bleach
Bleach is another effective DIY solution for removing green growth from concrete. Create a bleach and water solution, and use a deck brush to scrub the patio. For general cleaning and disinfecting, let the solution sit for about 6 minutes. For mould and mildew stains, allow it to sit for 10 minutes. Remember to wear protective gear and rinse nearby plants with water before and after applying the bleach solution to protect them from accidental exposure.
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Commercial products: Wet & Forget, BioAdvanced 2-In-1 Moss and Algae Killer
If natural methods and DIY solutions don't work for you, there are several commercial products available that can help remove algae, moss, and mildew from your concrete patio. Here is some detailed information about two popular options: Wet & Forget, and BioAdvanced 2-In-1 Moss and Algae Killer.
Wet & Forget
Wet & Forget is a gentle, non-acidic, and bleach-free formula that is safe to use on virtually any outdoor surface, including concrete patios. It has a neutral pH level of 8 and will not stain your patio like bleach, which has a much higher pH. Its neutral nature allows it to clean effectively over time with the help of wind and rain.
To use Wet & Forget, attach the product to your garden hose and turn on the water. Then, turn the On/Off dial to the On position and spray your patio thoroughly. Keep people and pets off the surface until it's completely dry, which should take around 4-5 hours. Depending on your weather conditions and whether your patio is in shade or sunlight, a single application can keep your patio clean for up to a year or longer.
BioAdvanced 2-In-1 Moss and Algae Killer
BioAdvanced 2-In-1 Moss and Algae Killer is a ready-to-spray formula that kills moss, algae, lichen, mold, and mildew. It is designed to be easy to use and can be attached to your garden hose. The non-bleach formula will not stain or harm lawns and other surfaces. It works quickly, with moss turning yellow and then brown within hours, and it can be washed away by hand or rain.
To use BioAdvanced 2-In-1 Moss and Algae Killer, attach the product to your garden hose and turn on the water. Use your thumb to activate the sprayer and spray the desired surface. The moss will quickly turn yellow, then brown, and can be washed away. One application can protect the treated area for up to a year.
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Pressure washing: correct nozzle, start at a distance, protect eyes
Pressure washing is a great way to remove green algae from your concrete patio. Here are some tips to ensure you do it safely and effectively:
Choosing the Correct Nozzle
Pressure washers typically come with a set of nozzles that vary in terms of the concentration of water spray they deliver. For concrete surfaces, a 0-degree red nozzle with a small circular hole in the centre is ideal. This nozzle delivers the thinnest, highest-pressure stream of water, perfect for cleaning small sections of encrusted dirt from hard surfaces. If you're looking to cover a larger area in less time, a yellow nozzle is a good option. It sprays a narrow pattern that's wider than the 0-degree nozzle but be careful as it can easily damage wood and paint.
Start at a Distance
When using a pressure washer for the first time, it's important to start at a distance to ensure you don't damage the concrete surface. Even if you're an experienced user, it's always a good idea to test the pressure washer on a small area first. This way, if there is any damage, it will only affect a tiny portion of your patio.
Protect Your Eyes
Eye protection is crucial when operating a pressure washer. Paint chips, cement pieces, grit, and water can all shoot back at your face, so wearing safety goggles or a full-face mask is highly recommended. If you find that your goggles fog up or get wet, try using anti-fog spray or coating them with Rain-X. Additionally, keep a glass towel in your pocket to wipe them off as you work. Remember, safety should always come first!
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Seal concrete: Joint-It Premium Seal, fluoropolymer barrier, reapply regularly
If you're looking for a long-term solution to protect your concrete patio from algae, mould, moss, and mildew, sealing your concrete is a great option. Joint-It Premium Seal is a powerful and effective sealant that can help keep your patio looking new all year round. Here's everything you need to know about using Joint-It Premium Seal to protect your concrete patio:
About Joint-It Premium Seal
Joint-It Premium Seal is an eco-friendly sealant designed for natural stone and concrete surfaces, including patios, paths, roof tiles, and walls. It creates an invisible barrier that protects your concrete patio from dirt, stains, moss, lichen, and algae. The fluoropolymer barrier is extremely compact, preventing contaminants from penetrating the stone. This sealant is also quick-drying and helps to enhance the durability of your concrete patio while reducing maintenance time.
Application Process
To apply Joint-It Premium Seal, follow these steps:
- Ensure the surface is clean and free from any contaminants, algae, or mould.
- Using a low-pressure spray, roller, or brush, apply the product to the point of saturation.
- If needed, add a second coat while the first coat is still wet. Do not apply a second coat if the first coat has dried.
- Do not allow the product to dry between applications.
- Clean equipment and tools with water immediately after use.
- Keep children and pets away from the treated area until the surface is completely dry.
Reapplication
Sealants wear off over time, so regular reapplication is necessary to maintain their protective properties. The frequency of reapplication will depend on various factors, including formula strength, foot traffic, and exposure to direct sunlight. In general, it is recommended to reapply a sealer every 3-8 years to effectively inhibit algae penetration.
Benefits of Joint-It Premium Seal
- Eco-friendly, non-flammable, and non-toxic
- Enhances durability and reduces maintenance time
- Keeps your concrete patio looking new
- Repels moss and lichen formation
- Suitable for surfaces with heavy foot traffic
- Does not change the appearance of the surface
- Prevents weakening of surfaces through freeze/thaw cycles
- Backed by BBA accreditation, CE mark, and ISO 9001 and ISO 14001 certifications
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Frequently asked questions
Concrete patios turn green due to the growth of algae, mould, moss, and mildew. These organisms thrive in damp, shaded areas. To prevent this, ensure your patio gets enough sunlight and has good drainage. Regularly clean your patio and remove any standing water.
There are several ways to remove green growth from your concrete patio. A popular method is to use a pressure washer, but this can potentially damage the concrete and surrounding plants. Other methods include using a mixture of vinegar, bleach, or commercial cleaning products. Always wear protective clothing and test new cleaning products on a small area first.
Long-term solutions include using a sealant on your concrete patio to prevent moisture from entering. You can also use copper, which retards the growth of algae. Additionally, ensure your patio is built on a slight slant to aid with drainage. Regular maintenance and cleaning will also help prevent green growth.