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View of a slate roof being cleaned using a cherry picker for access and steam cleaning to remove moss, algae and biofilm

Should You Pressure Wash Moss Off Roof?

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Steam Cleaning A Slate Roof From A Cherry Picker

Pressure washing is a popular method of removing dirt, stains, and grime from various surfaces, including roofs. It involves using high-pressure water streams to blast away the accumulated debris, leaving a clean and refreshed surface.

However, while pressure washing may seem like a quick and efficient solution for removing moss from your roof, it can also cause severe damage if not done correctly – especially when cleaning concrete roof tiles. Steam cleaning / hot pressure washing can be considered for cleaning clay tiles or cleaning a slate roof.

In this article, we’ll explore whether pressure washing is a suitable solution for mossy roofs, the risks, and what alternatives you can consider.

Why Is Moss Growing on Your Roof?

Before we dive into the pressure washing debate, it’s essential to understand why moss is growing on your roof in the first place. Moss is an expected growth that thrives in damp, shady, and humid environments. 

If your roof doesn’t receive enough sunlight and stays moist for extended periods, moss and algae can quickly take hold. Other factors contributing to moss growth include poor ventilation, blocked gutters, and an ageing roof.

The Risks of Pressure Washing Your Roof

While pressure washing may seem like a quick and easy solution for moss removal, it’s not without risks. Here are some of the reasons why you should think twice before pressure washing your roof:

It Can Damage Your Roofing Materials

Depending on your roof’s age, condition, and material, pressure washing can cause significant damage. For instance, high-pressure water streams can strip away the protective granules on concrete roof tiles, causing premature wear and tear. It can also dislodge or break tiles, loosen flashing, and compromise the overall structural integrity of your roof. If you have a flat roof, pressure washing can be considered.

It Can Create Water Intrusion

Pressure washing risks creating water intrusion, which can lead to leaks, mould, and mildew growth. If water seeps under your roof tiles, it can penetrate your roof’s underlay and insulation, causing water damage and rot. It can also affect your home’s interior, leading to musty odours, staining, and health hazards.

It Can Be Dangerous

Pressure washing your roof is not only risky for your roof but also for your safety. Climbing onto your roof can be dangerous, especially if you don’t have the right equipment, training, or experience. Pressure washing involves working with high-pressure water that can cause serious injuries, including cuts, bruises, and falls. It’s best to leave the job to professionals who have the expertise and equipment to handle the task safely.

Alternatives to Pressure Washing Your Roof

What are the alternatives if pressure washing is not the ideal solution for removing moss from your roof? Here are some options you can consider:

Manual Moss Removal

One of the most effective ways to remove moss from your roof is to do it manually. It involves using a stiff-bristled brush or scraper to gently remove the moss without damaging your roofing materials. While it may take longer than pressure washing, it’s a safer and gentler approach that doesn’t pose the risk of water intrusion or damage.

Chemical Treatments

Another option is to use chemical treatments to kill the moss and prevent it from growing back. Chemical treatments are available in spray or granular form and can be applied directly to your roof. They work by breaking down the moss and algae, making them easier to remove. However, chemical treatments should be used with caution as they can also harm plants and animals and may require multiple applications to be effective.

Zinc Strips

Installing zinc strips on your roof can also be an effective way to prevent moss and algae growth. Zinc strips are thin metal strips that are placed along the roof’s ridge and release a natural fungicide that inhibits moss and algae growth. While they may not remove existing moss, they can prevent it from returning and provide long-term protection for your roof. We do not offer this as a service but is is an option considered by some.

Regular Maintenance

The best way to prevent moss and algae growth on your roof is to practice regular maintenance. This includes keeping your gutters clean and debris-free, trimming overhanging branches, and ensuring proper ventilation. Regular maintenance can also help you detect and fix any issues before they become significant problems.

Should You Pressure Wash Moss Off Roof?

In summary, while pressure washing may seem like a quick and easy solution for removing moss from your roof, it’s not without risks. Pressure washing can damage your roofing materials, create water intrusion, and harm your safety. Instead, consider alternatives such as manual moss removal & biocide treatment to prevent moss and algae growth.

FAQs

Can I pressure wash my roof if I have moss?

No, it’s not advised to pressure wash your roof if you have moss. Pressure washing can damage your roofing materials, create water intrusion, and be dangerous for your safety. 

How do I remove moss from my roof without pressure washing?

You can remove moss from your roof manually using a stiff-bristled brush.

Can moss damage my roof?

Yes, moss can damage your roof by trapping moisture, creating water intrusion, and causing premature wear and tear on your roofing materials. It can also lead to costly repairs and compromise the structural integrity of your roof.

Can I pressure wash my roof if it’s new?

No, it’s not recommended to pressure wash a new roof. Pressure washing can damage your roofing materials and void your warranty. Instead, follow the manufacturer’s recommendations for maintenance and care.

How often should I clean my roof?

It’s recommended to clean your roof as frequently as required, especially if you live in an area with high humidity, rainfall, or moss and algae growth. We offer a 3 year moss free guarantee but some roof’s that our team cleaned 10 years ago are still clean & moss free today.

Conclusion

In conclusion, pressure washing is not advised to remove moss from your roof. While it may seem like a quick and easy solution, it can cause severe damage to your roofing materials, create water intrusion, and be dangerous to your safety. 

At The Roof Moss Cleaners, we provide professional roof moss removal services to keep your roof looking its best for years to come. Contact us today for more information about our services or to schedule an appointment! We look forward to hearing from you.

If you are considering having your roof cleaned then do not hesitate to contact Peter at The Roof Moss Cleaners Ltd on 01494 355645