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Roof Tile Manufacturers Warn: Do Not Jet Wash Your Roof
Maintaining a roof’s appearance and longevity is important, but how you clean roof tiles can make a critical difference. All major UK roof tile manufacturers explicitly advise against using high pressure jet washing on their products. This article compiles manufacturer backed evidence and industry guidance confirming that pressure washing (jet washing) roof tiles is not recommended. We’ll see exactly what companies like Marley, Redland (BMI), Sandtoft (Wienerberger), Russell Roof Tiles, and others say in their own words about jet washing. We’ll also include advice from roofing authorities like the NFRC (National Federation of Roofing Contractors) and the Roof Tile Association.
By the end, it will be clear why soft washing methods and manual removal of moss are safer alternatives, and how power washing can damage tiles, strip protective coatings, cause leaks, void warranties, and even risk your insurance coverage.
What Manufacturers Say: Official Warnings Against Jet Washing
Below is a summary of major UK roof tile manufacturers and their official stances on pressure washing. These are direct quotes from manufacturer documentation or experts, with sources:
| Manufacturer | Official Guidance (Direct Quote) | Source |
|---|---|---|
| Marley (concrete & fiber-cement tiles) | “The use of high powered jet washes is not recommended as it can damage the surface of the slate or tile, thus reducing its expected life considerably.” | Marley Roof Maintenance Guide |
| BMI Redland (clay & concrete tiles) | “On no account should a high pressure water jet be used to clean off moss and lichen growths from concrete tiles. This will result in erosion of the surface thereby reducing the potential lifespan of the roof tile.” | Roof Tile Association Guidance |
| Wienerberger (Sandtoft clay tiles) | “When cleaning a roof, it is crucial to avoid using high pressure jet washers. The forceful spray can damage the tile finish and strip away colour from concrete tiles… If a pressure washer is necessary, it should be on low pressure and directed from the apex downward to prevent water ingress.” | Wienerberger Blog – How to Clean Roof Tiles |
| Russell Roof Tiles (concrete tiles) | “High powered jet washes are not recommended as they can damage the surface of the tile, reducing its life considerably.” (Russell adheres to the same RTA guidance as above) | Russell Roof Tiles – Maintenance |
| Forticrete (concrete tiles, an Ibstock brand) | “Power washing the tiles will remove fines in the concrete which will affect the lifespan of the tile. As a manufacturer of concrete roof tiles we would not advocate power washing or recoating tiles as this would invalidate any guarantee.” | Forticrete Concrete Roof Tiles |
| Tudor Roof Tiles (handmade clay tiles) | “Remove heavy moss by chemical wash or careful hand scraping. Pressure washing should never be used on our clay tiles.” | Tudor Roof Tiles – Care Guide |
1 BMI Redland and Russell Roof Tiles are members of the Roof Tile Association (RTA). The quote shown is from the RTA’s official guidance, reflecting these manufacturers’ recommended practice.
Industry Authorities Agree
- NFRC (National Federation of Roofing Contractors): The NFRC has publicly warned homeowners against pressure washing roofs. They report that many moss removal “services” rely on “‘violent’ means such as power washing that may cause damage”, especially when combined with heavy foot traffic on a roof. The NFRC emphasizes that moss is usually cosmetic and “in normal circumstances, moss growths do not damage tiles or slates”, so aggressive cleaning is unnecessary. Instead, their advice to concerned homeowners is to consult a professional roofer for assessment rather than let someone blast the roof with high pressure. Read NFRC Guidance (PDF)
- Roof Tile Association (RTA): In a technical guide, the RTA representing manufacturers like Redland, Marley, Russell, Sandtoft, etc. advises that if moss must be removed, use a low-pressure water spray (about 4 to 5 bar) and never a high pressure jet. The guide states unequivocally: “On no account should a high pressure water jet be used… This will result in erosion of the surface, reducing the lifespan of the roof tile.” Visit the RTA Guidance Library
- NHBC / BSI: While the National House-Building Council (NHBC) and British Standards Institution (BSI) primarily focus on construction and installation standards, their emphasis on proper maintenance implies avoiding practices that could damage materials. Visit NHBC Website
