Why You Should Never Jet Wash Your Roof

It might seem logical to blast moss off your roof with a pressure washer — it works great on driveways, after all. But using high pressure on roof tiles can cause serious, expensive damage.

The Problem with High Pressure

A typical jet washer operates at 100-150 bar of pressure. That's powerful enough to strip paint, cut through grime, and — unfortunately — damage roof tiles.

1. It Can Crack and Chip Tiles

Roof tiles, especially older ones, can be brittle. High pressure water can crack, chip, or even break tiles completely. You might not notice the damage immediately, but hairline cracks will let water in and cause problems down the line.

2. It Forces Water Under Tiles

The angle and pressure of a jet washer can force water underneath tiles and into your roof space. This can cause damp, rot, and damage to your home's structure — problems that are far more expensive to fix than moss.

3. It Strips the Protective Surface

Many roof tiles have a protective coating or textured surface that helps them shed water. High pressure washing can strip this away, making tiles more porous and more likely to absorb water and grow moss in the future.

4. It Doesn't Kill the Growth

Even if you blast all the visible moss off, the roots and spores remain. Without biocide treatment, the moss will grow back — often faster than before because you've roughened the tile surface.

What Professionals Use Instead

Professional roof cleaners use methods specifically designed to clean without causing damage:

Low Pressure Cleaning

We use carefully controlled low pressure — typically around 60-100 bar, adjusted for each roof type. This is enough to remove growth without damaging tiles. Combined with the right technique and angle, it's safe and effective.

Manual Scraping

For older or fragile roofs, we remove moss by hand using specialist tools. This is the gentlest method and involves no water pressure at all.

Biocide Treatment

After cleaning, we apply a professional biocide that kills moss, algae and lichen at the root. This prevents regrowth and means your roof stays cleaner for years — not months.

The Bottom Line

Your roof is too important (and too expensive to replace) to risk with a DIY jet wash. Professional cleaning costs a fraction of roof repairs and gives you results that last.