The short answer: softwash cleans, and a coating restores appearance. A coating always goes on after a clean, never instead of one. Whether you need it depends on your tile type and how much cosmetic restoration you want. Many roofs need only the clean.
What this guide covers
1. What each treatment does
Softwash biocide treatment
A softwash applies a biocide at low pressure to the roof surface. Professional products are usually based on sodium hypochlorite. The treatment kills the living moss, algae and lichen, and rain then washes the dead growth away over the following weeks, since dead growth loosens.
Softwash treats the growth, yet it does not change the tile's colour or how much water the tile absorbs. Because shade and damp drive regrowth, the result still depends on your roof's conditions.
Roof coating
A roof coating is an elastomeric or acrylic layer, sprayed on after a softwash clean. It aims to do two things. First, it evens out faded tile colour. Second, it adds water repellency, so the surface soaks up less rain.
A coating changes how the roof looks and behaves at the surface, but it goes on a clean roof only. We do not claim that a coating makes a roof last longer. The NFRC advises caution about claims on roof life or thermal performance unless credible UK third-party accreditation backs them.
2. Side-by-side comparison
| Softwash only | Softwash + coating | |
|---|---|---|
| Treats moss & algae | Yes | Yes (softwash included) |
| Restores tile colour | No | Yes |
| Adds water repellency | No | Yes |
| Tiles we treat | Concrete, clay and slate | Concrete only |
| Our starting price (semi) | £350 | £1,100 |
| Our guarantee | 5-year regrowth protection | Manufacturer guarantee on the coating, plus our 5-year regrowth protection |
| Visible result | Builds over the following weeks | Colour at once, full clean over the following weeks |
3. Which tile types we coat
We coat concrete tiles only, and only where they are structurally sound. Here is how we treat each common roof type, because the answer differs for each.
- Concrete tiles: suitable for coating if the tiles are sound and the colour has faded
- Clay tiles: we do not coat them, so softwash cleaning is our treatment
- Natural slate: we do not coat it either, and softwash is our treatment
- Fibre cement slates: we assess these at survey before we recommend anything
Not sure what tiles you have?
Concrete and clay tiles can look alike from the ground. We identify the tile type at survey and advise you honestly, so you do not need to guess.
4. When coating is worth it
A coating can make sense in a few cases. Even so, check each point against your own roof, because every home differs.
- Your concrete tiles have faded noticeably, and look patchy even after cleaning
- The roof is structurally sound, with no cracked, slipped or broken tiles, because a coating is cosmetic and cannot fix structural faults
- You want to refresh the roof rather than replace it
- You are selling and want the roof to look its best
5. When softwash alone is enough
Coating is not always the right choice, and the NFRC's point that moss is rarely a problem applies here too. Softwash alone suits you in these cases, while a coating can wait.
- You have clay or slate tiles, because we do not coat them
- Your concrete tiles still have good colour, so a clean restores the look
- You want the lowest cost treatment that deals with the growth
- Some tiles are cracked or damaged, because they need repair before any coating
Our post on whether roof moss harms your house helps you judge whether the growth needs treating at all. Meanwhile, whether softwashing is safe for roof tiles covers the tile question.
If dark staining prompted the question, our article on what causes black streaks on roof tiles is a useful next step.
6. Costs compared
These are our own starting prices. However, a survey confirms the fixed price for your roof, since each roof differs.
| Treatment | Semi-detached | Detached |
|---|---|---|
| Softwash only | From £350 | From £450 |
| Clean + coat (combined) | From £1,100 | From £1,400 |
| Coat only (after a recent clean) | From £800 | From £1,000 |
We quote every price as a fixed price. We need a survey first, because tile type, condition and area decide the final figure.
To compare value, divide each price by the years you expect before the work needs repeating. We cannot promise a lifespan for a coating, so use the manufacturer's written guarantee as a guide. Then ask yourself whether the colour change is worth the extra cost to you. For the right property it can be, but plenty of roofs do not need it. See our roof coating service or soft wash roof cleaning pages for the details.
Not sure which is right for your roof?
We check tile type, condition and coverage at survey. Then we give you an honest recommendation, because the biggest job is not always the best one.
Get my free survey & quote7. Frequently asked questions
What is the difference between a softwash and a roof coating?
A softwash is a biocide cleaning treatment that kills moss, algae and lichen. A roof coating is an elastomeric or acrylic layer, sprayed on after cleaning, to even out colour and add water repellency. Softwash treats biological growth, whereas a coating changes how the surface looks and behaves, so the two work together.
Is roof coating better than softwash?
They do different jobs, so better depends on what your roof needs. If you have moss to treat, softwash is the answer. If your concrete tiles have also faded, a coating adds a cosmetic layer, but it never replaces the clean.
What types of tiles can be coated?
We only coat concrete tiles that are structurally sound. We do not coat clay tiles or natural slate. For those roofs, a softwash is the treatment we offer, and a roofing specialist can advise on anything else.
How much does roof coating cost compared with softwash alone?
Our softwash starts from £350 for a semi-detached house and £450 for a detached one. Clean and coat together starts from £1,100 and £1,400, and coating only starts from £800. A survey confirms the fixed price for your roof.
Does a coated roof still need a softwash?
A coating changes the surface, but it does not make a roof immune to growth. Shade and damp still matter, according to the RHS, so a coated roof in a shaded spot can still go green. We advise on the right timing at survey.
What happens if I coat a roof without cleaning it first?
Growth left underneath can keep spreading, and it may spoil the finish. That is why we never coat a dirty roof. Cleaning first is part of our process, and the clean and coat price already covers it.