Search for roof cleaning and you'll find two camps, each saying the other ruins roofs. Both are partly right.
High pressure is the problem
A jet washer held close to a tile can strip its surface and crack old concrete. That's why we never use aggressive high pressure.
Low pressure, done right
On a sound roof, low pressure with attachments designed for roofs removes moss quickly and evenly, and you see the result straight away. It's our main method.
Soft washing
Soft washing uses a cleaning solution at almost no pressure. It's ideal for older or weathered tiles and for algae and lichen. It's gentler on the surface, and the chemistry does the work.
Hand scraping
For very heavy moss or fragile roofs, lifting the moss by hand is the safest first step.
The part both need
Whatever the method, a biocide treatment afterwards is what stops the growth coming back. Without it, any method is a short-term fix.
