Decision Guide
Clean, coat or replace?
Not every tired-looking roof needs replacing. In many cases, the first step is understanding whether the problem is surface moss and staining — or something deeper.
Start with the right question
The most expensive option isn't always the right one — and the cheapest isn't either.
When a roof starts to look tired, mossy or stained, it's easy to assume the only answer is a full replacement. But that's often not the case. The right first step is to work out whether the problem is on the surface of the roof — moss, algae, staining and debris — or whether there's an underlying issue with the roof itself.
This guide walks through the three options in plain terms, so you can make a sensible decision before spending serious money.
Option 1
Cleaning — the surface solution
Cleaning removes moss, algae, staining and built-up grime from the roof surface. It's the right answer when the roof itself is in good shape but looks tired because of what's growing on it. It's also the most affordable option — see our cost guide — and it lets you — and any roofer — see the true condition of the tiles underneath.
Cleaning may help when:
- The roof is structurally sound
- Moss and staining are the main problems
- Tiles remain secure
- Gutters are blocked or dirty
Option 2
Coating & treatment — slowing the return
After cleaning, a biocide treatment can target the organic growth that causes moss and algae to return, helping the roof stay cleaner for longer on suitable surfaces. It's an optional follow-up, not a cure-all — and we won't promise fixed lifespans, because regrowth depends on exposure, shading and the roof material.
Treatment makes most sense on roofs that are cleaned and in good condition, where regrowth has been quick in the past. It's not a substitute for fixing a damaged roof. See our roof treatment page for more detail.
Option 3
Replacement — when cleaning isn't enough
Replacement is the right answer when the roof itself is failing — not just dirty. Cleaning over a roof that needs structural work is a waste of money, so it's important to recognise the signs that point to a roofer rather than a clean.
A roofer should inspect when there are:
- Slipped or broken tiles
- Active leaks inside the home
- Damaged or failing flashing
- Failing ridge or pointing
- Visible structural defects
See our companion guide, Roof Cleaning or Roof Repair?
Why It Matters
The right choice saves money and stress
Save money
Cleaning is far cheaper than replacement — and may be all you need.
Extend lifespan
Careful cleaning and treatment help protect a sound roof.
A cleaner, healthier home
Less moss and debris means better drainage and a brighter roof.
Still unsure which option is right?
Send us a photo of your roof and we'll give you an honest view on whether cleaning, treatment or a closer inspection is the right next step.