Roof Tile Manufacturers Don’t Recommend Jet Washing

By Mark Cave April 03, 2025

Best Practices for Cleaning Roof Tiles Without Causing Damage

Split-view of a tiled roof showing one half clean from jet washing and the other half weathered, highlighting the damage caused by pressure washing. Text overlay reads: 'Do not use a jet washer to clean your roof.

Introduction

Maintaining your roof is essential for the long-term durability and appearance of your home. Over time, roofs can accumulate moss, algae, lichen, and other debris. While many homeowners look to pressure washing (also known as jet washing) as a quick solution, this method can be harmful—particularly to tiled roofs. Despite the short-term satisfaction of a clean surface, the long-term consequences can be severe: broken tiles, water ingress, voided warranties, and even denied insurance claims.

This in-depth guide brings together advice directly from leading UK roof tile manufacturers and explores how jet washing can severely damage your roof, shorten its lifespan, and impact your home insurance coverage. By the end, you’ll know exactly why you should avoid jet washing your roof—and what to do instead.

Close-up of terracotta roof tiles above a gutter containing orange sediment, showing how jet washing has stripped protective granules from the tiles. Text overlay reads: 'Roof tile manufacturers don’t recommend jet washing.

Manufacturer Warnings: Straight from the Source

Marley: “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 Tile Maintenance
Wienerberger: “High-pressure jet washers can damage the tile finish and strip away colour from concrete tiles. If pressure washing is necessary, it should be set to low pressure and directed from the apex downward to prevent water ingress.” Wienerberger Roof Cleaning Guide
Tudor Roof Tiles: “Pressure washing should never be used on their tiles, as it can cause severe damage to the roof.” Tudor Roof Tiles Care Guide

Close-up of a roof showing a clear contrast between a jet-washed tile and an unwashed tile, with visible surface erosion and loss of protective coating on the cleaned side, illustrating the damaging effects of pressure washing.

The Specific Risks of Jet Washing a Roof

Cracking and Breakage of Tiles – High pressure can crack or fracture older tiles.
Stripping Away Protective Coatings – Tiles lose surface protection, exposing porous material.
Water Ingress – Water is forced beneath tiles, potentially causing leaks.
Dislodging Mortar and Ridge Tiles – Weakens tile joints and structural points.
Accelerated Aging – Reduces expected lifespan of roof tiles significantly.

Real-World Consequences: Insurance Implications

Oakleafe Loss Assessors: Insurers may reject claims caused by homeowner negligence. Oakleafe Claims
PCLA: Roof damage caused by poor maintenance may be denied. PCLA

Safer Alternatives to Jet Washing

Soft Washing: Uses low-pressure spray with cleaning solutions.
Manual Cleaning: Hand scraping and brushing off moss and dirt.
Chemical Treatments: Moss and algae killers approved for roofs.
Professional Roof Maintenance: Experts use safe, non-invasive methods.

Preventative Maintenance Tips

Trim overhanging trees to reduce moss growth.
Ensure proper roof ventilation to keep things dry.
Clean gutters regularly to prevent water buildup.
Install copper or zinc strips to discourage moss.
Apply a biocide like Soft Wash Pro 50

Final Thoughts

It might be tempting to fire up a jet washer and blast the moss away in a couple of hours, but the damage it causes could cost you thousands. Always follow the advice of roof tile manufacturers, and if you're unsure, contact a professional who specializes in soft washing or roof-safe cleaning techniques.

Your roof protects your entire home—treat it with the care it deserves.