How To Remove Green Algae From A Wood Deck

Green algae on deck surfaces are an unsightly yet common issue that can accumulate over time. If your deck is looking green after a long summer of humid weather or winter snowfall, read on to learn the best ways to kill algae on deck, clean it off, and prevent regrowth.

What Is Green Algae?

And how do you tell it apart from moss, mold, and mildew? 

Algae is a slimy, green film that grows on wood in wet, dark conditions. Moss is also green and grows in similar conditions but is soft and fuzzy to the touch. Mold is a fungus that appears on wood as greenish-black streaks. Untreated, mold spores can pose a health risk to people and pets when inhaled.

While algae, moss, and mold are different, they are all equally harmful to your wood deck and should be treated right away. 

Why It’s Important to Remove Algae from Your Deck

While green algae on a deck may not be aesthetically pleasing, its presence on your wood deck can pose significant hazards. It’s crucial to understand the importance of promptly removing algae to prevent potential damage and ensure the safety of your outdoor space. Here are some reasons why algae removal is essential for the maintenance of your wood deck:

1. Moisture Damage: Algae and mold thrive in moist environments. When algae grows on your wooden deck, it retains moisture that can seep into the wood. Over time, this moisture absorption can lead to the deterioration of the deck’s structural integrity. Additionally, the presence of moisture within the wood can cause it to swell, shrink, or warp, leading to unsightly cracks and even splinters. By removing algae promptly, you mitigate the risk of moisture-related damage to your wood deck.
2. Slippery Surfaces: Algae-covered surfaces become extremely slippery, posing a significant risk of slips and falls. This hazard is particularly concerning if algae accumulates on your deck stairs or other high-traffic areas. The slimy film created by algae can make it easy for someone to lose their footing, resulting in injuries. To ensure the safety of your family and guests, it’s crucial to remove algae promptly and maintain a clean, slip-resistant deck surface.
3. Regrowth and Spreading: Algae is notorious for its ability to regrow quickly. If not adequately cleaned, even a small remnant of algae can rapidly multiply and cover your deck once again within a few weeks. Additionally, algae spreads easily, especially in damp conditions, making it even more challenging to control its growth. To prevent further infestation, it’s important to remove any green spots or algae patches as soon as they appear. By addressing the issue promptly, you can minimize the chances of widespread algae growth and reduce the need for frequent cleaning.
4. Preserving Deck Appearance: A well-maintained wood deck enhances the overall beauty and value of your outdoor space. However, the presence of algae can detract from its visual appeal, making the deck appear dirty, neglected, and uninviting. Regular removal of algae helps preserve the natural beauty of your wooden deck and ensures that it remains an attractive and enjoyable area for relaxation and entertainment.

To effectively remove algae from your wood deck, consider using appropriate cleaning techniques and products specifically designed to combat mold and algae. Additionally, applying a quality deck stain or sealant can provide an extra layer of protection against future algae growth, extending the lifespan of your deck while maintaining its appearance.

What Factors Aid Algae Growth?

Knowing what conditions cause green algae to grow can help you prevent it from flourishing on your wood deck, patio, and wooden outdoor furniture. By understanding the factors that contribute to algae growth, you can take proactive measures to keep your deck clean and algae-free.

Algae thrives in a dark, damp environment, but it doesn’t grow overnight. That means with proper maintenance, it’s relatively easy to prevent your wood deck from turning green. The two primary factors to be mindful of are debris and moisture – they create an environment conducive to the growth of green algae, mold, and mildew on your deck boards and wood deck.

• Debris: Accumulated leaves, pine needles, and other organic matter on your deck create a barrier that blocks sunlight from reaching the surface of the wood. This accumulation of debris provides a perfect breeding ground for green algae, mold, and mildew. To prevent this, it is important to regularly sweep or blow away any debris that may settle on your deck. By keeping the surface clear, you allow sunlight to penetrate and inhibit the growth of green algae.
• Shade: If your deck is naturally shaded by trees or your home, simply sweeping away debris may not be sufficient to ward off green algae. In such cases, an annual deep cleaning of your deck becomes essential to keep algae and moss at bay. Deep cleaning involves using appropriate cleaning agents and techniques to remove any existing algae and prevent its regrowth. This thorough cleaning process helps to maintain the appearance and longevity of your deck boards.
• Moisture: The presence of excessive moisture is another factor that promotes the growth of green algae on your deck. If water tends to pool and sit on certain areas of your deck, it creates an environment conducive to the growth of algae. While most decks have sufficient spacing between planks to allow for water drainage, it is essential to ensure that your deck is in good condition. Sealed or uneven planks can impede proper drainage, leading to increased moisture retention.

With these preventative measures in place, you can enjoy a beautiful and algae-free outdoor space throughout the year.

Cleaning Solutions that Remove Algae 

The cleaning method depends on what material your deck’s made from. Follow this guide for composite deck cleaning tips. Follow this cleaning guide for Trex decks.

When it comes to removing algae from your wooden deck, you have quite a few options. The most common you’ll hear is bleach, but bleaching your deck can alter its color and even corrode the metal fasteners keeping your deck together. For these reasons and more, bleach is not recommended by the Occupational Safety and Health Administration for algae and mold removal. 

If you’re looking for alternative algae cleaning solutions, here are a few suggestions: 

• Moss and algae removal products: There are quite a few different products on the market that are designed specifically to remove moss and algae from decks. Many of these products allow you to “wet it and forget it” but tend to be more expensive than DIY cleaning solutions. 
• Hydrogen peroxide: Another cleaner you probably already have in your home is hydrogen peroxide. However, it’s important to understand that hydrogen peroxide alone won’t kill algae growth – instead, it creates a foamy surface that helps lift the algae away from the surface, making it easier to scrub away.
• White distilled vinegar: White vinegar is a popular natural cleaner that can be used both inside and outside. Simply combine one gallon of water with one cup of white vinegar and scrub the deck with the solution to remove algae, mold, and mildew.
• Pressure washing: If you don’t want to use any products or chemicals on your deck, you can blast algae away with a pressure washer. Just be careful not to use too much pressure – if you’re not careful, you can damage the soft wood. 

How To Prevent Future Algae Growth

Unfortunately, there is no magic spell to cast on your deck to prevent algae growth, but there are some measures that can be taken to slow or prevent it. 

The first is cleaning annually or biannually. Algae spreads quickly, so the longer you allow it to build up, the more it grows. This is why it is important to have a regular cleaning schedule. It’s also a good idea to seal your deck with a quality water repellant. Algae needs moisture or standing water to grow, so keeping your deck dry is key.

If you have questions about deck maintenance, our knowledgeable and friendly team would love to hear from you – send us a message or call Decks & Docks Lumber Company at 866-528-9663.