| July 11, 2026
Soft Wash vs Pressure Wash for Roof Cleaning: Which Is Right?
Before any roof is recoated, it has to be cleaned — years of moss, lichen, dirt and old coating have to come off so the new membrane bonds properly. But how you clean matters. The two main methods — pressure washing and soft washing — suit different roofs, and using the wrong one can do real damage. Here’s how to tell them apart.
The difference in a sentence
- Pressure washing uses high-pressure water to physically blast growth and build-up off the surface.
- Soft washing uses low pressure plus a cleaning treatment that kills moss, lichen and mould so it can be gently rinsed and then dies off over time.
When pressure washing is the right tool
For most sound tile roofs heading into a restoration, high-pressure cleaning is exactly right. It’s the fastest, most thorough way to strip:
- Thick moss and lichen
- Chalky, failed coating on old cement tiles
- Ingrained dirt and surface build-up
Getting back to a clean, sound surface is essential for a coating to grip — a membrane applied over moss or loose material simply peels. This is why high-pressure cleaning is the first step in our roof restoration process.
The key is skill: correct pressure, the right nozzle, and the right angle so you clean the tile without driving water up under it or eroding the surface.
When soft washing is the better choice
Soft washing comes into its own where high pressure would cause damage, such as:
- Fragile or aging terracotta with a delicate glaze
- Brittle tiles that could crack under force
- Situations where you want to kill the moss and lichen at the root so it doesn’t come straight back
- Delicate roof features, or where controlling water spread and overspray onto neighbouring property matters
Because soft washing relies on a treatment rather than brute force, it deals with the biological growth more completely — the moss dies rather than just being knocked off the surface. The trade-off is that it’s gentler and often slower to reveal a fully clean surface.
The risks of getting it wrong
Pressure washing in the wrong hands, or on the wrong roof, causes the damage we get called to fix:
- Cracked or chipped tiles from too much force
- Eroded surfaces on already-weathered cement tiles
- Water driven under tiles and flashings, into the roof space — a leak caused by the cleaning, not the weather
- Stripped pointing on ridge caps
This is why roof cleaning isn’t really a DIY or a job for a general pressure-washing operator — it’s part of roofing, done by people who know how tiles behave.
Which will your roof need?
Often it’s a combination: high-pressure cleaning to strip a sound cement roof back to a coatable surface, or a gentler soft-wash approach for fragile terracotta or where growth keeps returning. The right call depends on your tile type, its condition and age — which is exactly what an inspection tells us.
Whichever method your roof needs, cleaning is just the start. On a restoration it’s followed by repairs, re-pointing and recoating — cleaning alone makes a roof look better for a while, but it’s the full process that protects it.
Get the right clean for your roof
We assess every roof before we touch it and choose the cleaning method that gets it properly clean without damaging your tiles — then take it through to a full restoration if that’s what you’re after.