Removing moss and algae from patios and driveways

How to Use Sodium Hypochlorite to Kill Moss, Algae and Lichen on Driveways and Patios

A clean driveway or patio can completely transform the appearance of your home. However, over time, moss, algae and lichen can begin to take hold, creating slippery surfaces, staining paving and making outdoor areas look neglected.

One of the most effective treatments for removing these stubborn organic growths is sodium hypochlorite - a professional-strength cleaning solution widely used by exterior cleaning specialists.

In this guide, we’ll explain how sodium hypochlorite works, why it’s so effective, and how to use it safely for long-lasting results.

What Is Sodium Hypochlorite?

Sodium hypochlorite is a powerful cleaning and sanitising agent commonly found in professional exterior cleaning products.

It works by breaking down organic matter at a chemical level, making it highly effective against:

• Moss
• Green algae
• Black spot algae
• Lichen
• Mildew
• Organic staining

Unlike pressure washing alone, which often only removes surface contamination temporarily, sodium hypochlorite kills spores deep within porous paving surfaces, helping reduce rapid regrowth.

Professional cleaners regularly use products such as ProClean Moss and Algae Cleaner for effective driveway and patio cleaning.

Why Moss, Algae and Lichen Grow on Patios and Driveways

Outdoor hard surfaces are constantly exposed to moisture, dirt and airborne spores.

Conditions that encourage growth include:

• Shaded areas with limited sunlight
• Poor drainage
• Damp conditions
• Organic debris such as leaves and soil
• Porous paving materials that retain moisture

Once established, moss, algae and lichen can become difficult to remove without chemical treatment.

Benefits of Using Sodium Hypochlorite

Professional exterior cleaners often choose sodium hypochlorite because it provides fast and effective results.

Fast Acting

Visible cleaning results can often be seen within minutes of application.

Kills Organic Growth at the Root

Rather than simply removing surface growth, sodium hypochlorite destroys spores and organic contamination at the source.

Reduces Regrowth

Surfaces stay cleaner for longer compared to pressure washing alone.

Restores Surface Appearance

It helps brighten paving surfaces while removing unsightly staining and discoloration.

Improves Safety

Removing slippery algae and moss helps reduce slip hazards on patios, paths and driveways.

How to Apply Sodium Hypochlorite Safely

Step 1: Clear the Area

Remove outdoor furniture, pots, leaves and loose debris from the surface before treatment.

Step 2: Wet Surrounding Plants

Pre-soak nearby grass, shrubs and flower beds thoroughly to help minimise the risk of chemical damage.

Step 3: Dilute Correctly

Always follow the manufacturer’s guidance carefully.

The required strength will depend on the contamination level and the type of surface being treated.

Typical professional dilution ratios include:

• Light algae - 1:4
• Moderate contamination - 1:2
• Heavy moss or lichen - stronger mixes may be required

Always carry out a small test patch before full application.

Step 4: Apply Evenly

Use a low-pressure sprayer to apply the solution evenly across affected areas.

Avoid windy conditions and overspray onto surrounding surfaces.

Step 5: Leave to Dwell

Allow the solution to dwell for approximately 15-45 minutes depending on the severity of contamination.

Do not allow the product to dry fully during hot weather.

Step 6: Rinse Thoroughly

Rinse the area thoroughly with clean water or a low-pressure rinse.

A light pressure wash can be used if required.

Step 7: Repeat if Necessary

Heavy lichen contamination may require a second treatment for complete removal.

Important Safety Precautions

Sodium hypochlorite is highly effective but should always be handled carefully.

Always:

• Wear gloves and eye protection
• Avoid skin contact
• Never mix with acids or other chemicals
• Keep children and pets away during treatment
• Avoid overspray onto plants
• Use only in well-ventilated outdoor areas

Why Pressure Washing Alone Often Fails

Pressure washing can remove visible contamination but often leaves microscopic spores embedded within the surface.

This means moss and algae frequently return within a short period of time.

Combining pressure washing with sodium hypochlorite treatment provides:

• Deeper cleaning
• Longer-lasting results
• Improved stain removal
• Reduced ongoing maintenance

Professional vs DIY Treatment

DIY treatment can be effective for light contamination, but professional exterior cleaning services often achieve superior results through:

• Correct chemical dilution ratios
• Specialist application equipment
• Surface-safe cleaning methods
• Full safety compliance
• Treatment plans to help reduce regrowth

For heavily contaminated driveways and patios, professional treatment is often more effective and longer lasting.

Recommended Products

For professional-level cleaning results, consider using:

• ProClean Moss and Algae Cleaner
• Professional sprayers and application equipment
• Protective gloves and safety equipment

You can also browse our full range of landscaping products for patio and driveway maintenance.

Final Thoughts

If your driveway or patio is covered in moss, algae or lichen, sodium hypochlorite remains one of the most effective cleaning solutions available.

Used correctly, it kills organic growth at the source, restores surface appearance, improves safety and helps outdoor surfaces stay cleaner for longer.

Whether you’re maintaining your own patio or carrying out professional exterior cleaning, ProClean Moss and Algae Cleaner provides a reliable and cost-effective solution for professional results.