Green cushions, grey crusting or a flat film all look much the same from the ground, and each needs completely different treatment. Here is how to tell them apart without going up a ladder.
Valley damp and hedgerow shade mean these roofs simply do not get the drying hours an open site does. Moss establishes in the tile laps first, lichen follows on the older slate, and algae fills in between the two.
By far the most common growth on a valley roof, and the one that starts in the tile laps where water lingers longest. It is soft, deep and liftable by hand, which is exactly how it comes off before anything is applied. Treat it at the root afterwards and it stays away far longer than most people expect.
Flat, crusted and grey-green or a dull orange, and bonded into the surface rather than sitting on it. That is why it will not brush off and why force is the wrong answer. A biocide left the time it needs reaches the holdfast, and the roof clears steadily from there.
The flat green film that fills the space between the moss and the lichen. It has no depth to it at all, which is the giveaway from the ground. It is also the quickest of the three to clear, so a roof that only has this on it is a smaller job than it looks.
Get the name wrong and you end up buying the wrong treatment.
Your photographs do most of the work. Colour, whether it has depth or lies flat, how far it has run and which elevation gave way first. Between them those four usually settle it without anybody having to come out to you.
The answer decides the approach. Algae goes quickly under a biocide. Moss is lifted by hand before anything is applied. Lichen needs its dwell time, and we call back to check it after.
Then you are told, in ordinary language, what you have and what will move it. Where it turns out to be more field dust than growth, we say so, and it becomes a far smaller job than you had budgeted for.
The read people find most useful here, and a check you can run yourself.
On a shaded valley roof that happens faster than most people expect. The guide explains what regrowth actually needs, and what stops it properly.
The Roof Check takes about a minute from the ground and tells you whether this is a job for now or for next year.
Shaded render and old boundary walls carry exactly what the roof does, and they are treated the same way.
What gets asked once somebody has stood back and had a proper look.
Depth is the giveaway. Anything standing proud of the tile with a soft, cushioned look is moss. Anything flat, crusted and pale — grey-green or a dull orange — is lichen, bonded into the surface rather than sitting on it. A photo from the ground is usually enough for us to settle it for you.
Removal takes off what has depth to it; treatment kills what is bedded into the surface and cannot be reached by hand. A heavily mossed roof wants both, in that order. A roof with only a film on it often needs the treatment alone, which is the cheaper of the two. We will say so if that is your situation.
Sunlight and drying time, almost always. Whichever side sees least of the sun holds moisture longest and grows first. It tells us something useful about the house, and it does not change the job: the whole roof is done as one.
Both, over time. Thick moss holds water against the covering, lifts at the edges of tiles and slates as it grows, and sheds into the gutters until they stop running. Once it is dealt with it stops being a problem, and stays that way for a good while.
Six organisms, what each does to tile and slate, and the treatment each needs, set out properly on the main roof cleaning page rather than repeated here.
A photograph from the garden is more use to us than any description, and it is quicker for you.
Phone: 089-949-1525
WhatsApp: Send a couple of photos
Email: info@eireshine.ie
Send it through. You will get the name of it and a straight view on whether it is far enough along to be worth treating. Often it is not, which is good news.
One picture of the worst elevation is usually enough to go on.
