How Long Does a Roof Clean Last?

One of the most common questions we get asked is "how long will my roof stay clean?" The answer depends on several factors, but with proper treatment, you can expect years of protection.

The Short Answer

With professional cleaning and biocide treatment, most roofs stay clean for 2-5 years. Some roofs stay clean even longer, while others in particularly challenging conditions may need attention sooner.

What Affects How Long It Lasts?

1. Roof Orientation

North-facing roofs get less direct sunlight and stay damper, which encourages moss growth. South-facing roofs typically stay cleaner for longer because they dry out faster.

2. Nearby Trees

Trees shade your roof (keeping it damp) and drop debris that holds moisture. Overhanging branches can significantly reduce how long your roof stays clean. Trimming back trees can help.

3. Local Environment

Roofs in rural areas with clean air often develop lichen faster. Urban areas may see more algae due to pollution. Coastal areas face salt spray which can affect growth patterns.

4. Roof Pitch

Steeper roofs shed water faster and tend to stay cleaner longer. Flatter sections where water pools are more prone to regrowth.

5. Tile Type

Smooth tiles stay cleaner than textured ones. Concrete tiles are more porous than clay and may need more frequent cleaning.

Why Biocide Treatment Matters

The biggest factor in how long your roof stays clean is whether biocide treatment was applied. Here's the difference:

• • Cleaning only: Moss can start regrowing within 6-12 months
• • Cleaning + biocide: Protection typically lasts 2-5 years

Biocide kills moss, algae and lichen at the root and leaves a residual protection on your tiles. This is why all our cleaning includes biocide treatment as standard.

Maximising Your Results

To get the longest life from your roof clean:

• • Trim back overhanging trees and branches
• • Keep gutters clear so water drains properly
• • Consider a maintenance clean every 3-4 years rather than waiting for heavy growth