Green film, dark streaks, reddish patches or grey crusting — each one is a different organism and each needs a different treatment. Here is how to tell them apart, standing in your own garden.
Seafront exposure puts salt mist and windblown sand onto the tiles, and that combination holds damp against the surface. Algae takes hold first, moss follows into the north-facing pitches, and the two together are most of what we treat here.
The thin green sheen that appears first, usually on the shaded verges and the north-facing pitch. It is a single-cell film rather than a plant, which is why it looks flat. On its own it is the easiest of these to shift, and dealing with it early keeps moss and lichen from getting a foothold behind it.
The reddish-brown tone you see on tiles and fascia within a few kilometres of the sea. Salt aerosol keeps the surface damp long after the rain has stopped, which is exactly what it wants. It responds very well to biocide treatment, so a coastal roof carrying it is a straightforward job.
The cushions that stand proud of the tile and gather debris in behind them. Leave them long enough and they hold water against the covering and shed into the gutters. Once the moss is taken off by hand and treated at the root, the roof stops being a maintenance problem for a good while.
Naming it wrong is how people pay for the wrong treatment.
We work from your photos — colour, texture, how far it has spread, and which elevation went first. For most roofs that is enough to price it, and you have an answer the same day.
Each organism gets a different approach. Algae clears quickly under biocide. Moss comes off by hand first. Lichen needs dwell time and a follow-up.
You get told what it is in plain terms and what will shift it. If the roof has another year in it, we will say so and you can put the money elsewhere.
A short read and a free check you can run from the ground.
It does not look like anything living, which is why it gets scrubbed at rather than treated. Our guide sets out what red algae actually is and why it shows up along this coast.
Our Roof Check runs through what to look for from the ground in about a minute. Plenty of roofs turn out to have another season in them.
We cover Ballymoney and Courtown along the same stretch of coast. Roofs this close to the water carry the same three growths, so we know them from the photos.
Salt mist does not stop at the roofline. Render and boundary walls on seafront elevations carry the same red and green algae, and softwashing treats them the same way.
The questions people ask once they have had a proper look.
What you are looking at is red algae, or a mix of red and green together. It shows up within a few kilometres of the sea because salt aerosol holds moisture against the tile after rain. A biocide treatment clears it, and we see plenty of it.
Moss sits proud of the tile in cushions and looks soft — you could lift a clump with your fingers. Lichen is flat, crusted and grey-green or pale orange, and it will not lift, because it bonds into the surface. If you see texture and depth it is moss. If it looks painted on, it is lichen.
More often than an inland one, in our experience. Salt film and algae re-establish faster where the air carries moisture off the sea. A biocide treatment after cleaning typically holds a roof clear for twelve months or more, and we will tell you honestly at the estimate stage whether yours is at that point yet.
Because it dries more slowly. The pitch that gets least sun, or sits under a tree or a taller building, stays damp for longer after every shower, and damp is what growth needs. It is completely normal, and both sides get treated together anyway.
Six organisms, what each one does to tile and slate, and the treatment each needs. You will find the lot on the main roof cleaning page rather than repeated here.
Two shots from the ground is enough for us to tell you what you are dealing with.
Phone: 089-949-1525
WhatsApp: Send a couple of photos
Email: info@eireshine.ie
Send it over. We will tell you which organism it is and whether it is worth treating yet.
A photo from the ground tells us more than a description does.
