Roof coatings
Is a roof coating worth it after cleaning?
A coating can change how a roof looks and wears, but it is no repair. Below: when it makes sense, when not, and what to ask first.
The short answer
A roof coating is worth considering only when the roof is sound and the coating has a clear job, because it will not mend a fault. It goes on a clean, dry surface, so cleaning comes first. If tiles are cracked, slipped or the underlay is tired, the money is better spent on the repair. Ask for the maker's data sheet before agreeing to anything, and for what it says about your type of tile.
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What a coating is meant to do
A coating is a layer put onto the surface of a roof, usually to change its appearance and to protect the surface. It is applied after the roof has been cleaned, because it needs a clean, dry base to bond to. A coating over moss or loose growth fails to bond properly, and the growth keeps living underneath it.
That is why the clean comes first, whatever the product. The cleaning is the foundation, and the coating sits on top of it. A coating cannot make up for a poorly cleaned roof, and it does nothing for the tile underneath.
Products differ widely. Some are clear sealers, some are pigmented, and each maker gives different instructions for different surfaces. Published roof lifespans are given for the materials, not for what is painted on them, so a coating is not tied to a longer life.
Some owners ask for a coating because the roof looks tired after the clean. That can be a fair reason, but a roof that looks tired may also be telling you about its condition, and the survey is where that gets sorted out from appearance.
When a coating makes sense
There are good reasons to coat a roof, and they all start with a sound roof.
- The tiles are whole, firm and cleaned
- You want a particular finish or colour
- The maker states the product suits your tile type
- You accept that it will need looking after
On that basis a coating is a decision about appearance and surface care. It is a fair choice, as long as you know what you are buying. It is not a way to avoid replacing a roof that is worn out, and a coating on a failing roof only delays the point when the truth comes out.
We look at the roof first and say whether a coating is sensible. If the answer is no, we tell you that and why. If you want one, the written price covers the clean and the coating together as one total after the survey.
A coating can also be done later. There is no rush after a clean, and waiting a season lets you see how the roof settles, whether growth returns quickly, and whether the money would be better spent elsewhere on the house.
When a coating is the wrong spend
These findings change the advice.
| What we find | Better first step |
|---|---|
| Cracked or slipped tiles | Repair them |
| A leak into the loft | Trace and fix the fault |
| Worn-out underlay or battens | Plan a re-roof |
| Loose or flaking old paint | Check what is there first |
A coating over a fault does not cure it. Water can still enter through a gap that the layer covers, and the fault is harder to find afterwards. On a roof close to the end of its working life, a coating is money spent on a covering that will be replaced.
We would rather tell you that plainly than sell a coating on a roof that needs more. Our answer on roof replacement is worth a look if a survey points that way.
If you are unsure which category your roof falls into, a survey sorts it out. We go up, look at every slope, and tell you what we found with photos. Sometimes the survey shows the roof only needs the clean, and sometimes a repair has to come before anything else. You decide from there.
Questions to ask before agreeing
Put these to anyone offering a coating, ours included.
- What does the maker say the coating is for, and is it suited to my tiles?
- What condition must the roof be in before it goes on?
- How is the surface prepared, and how long must it dry?
- What will it look like after a few seasons, and what does looking after it involve?
- What happens to it if a tile has to be replaced later?
The last question is easy to forget. A coating across a whole slope can make a later repair visible, because new tiles will not match. The data sheet answers most of these, and if a firm cannot show you one, that is worth knowing.
The roof cleaning and moss removal page covers the cleaning that comes first, and our answer on roof biocide treatment covers the spray that treats growth.
Answers in writing are best. A short written note from the firm on what the coating is, how it is put on and what is expected afterwards is a fair thing to ask for, and a firm that is confident in its product will give it readily.
More questions
Does a roof coating stop moss growing back?
We cannot promise that. Growth returns on surfaces that stay damp and shaded, and a coating does not change that. Some products make claims about it, so read the maker's data sheet and ask what it says, rather than relying on a salesperson. Treatment and a clear, dry roof do more.
Can a coating be applied straight after a clean?
Not straight away. The roof must be clean, sound and dry, and the product maker sets how long to wait and in what weather. We would survey the roof first, deal with any repairs, and then agree whether a coating is worth doing at all.
Tell us what's wrong with the roof.
You'll get one written total price.