Living in beautiful Donegal means we deal with plenty of Atlantic moisture. While great for our landscape, it’s the perfect breeding ground for red, green, and black algae to take over your home’s exterior.
At BioWash, we specialize in safely removing these stubborn stains, restoring your home to its original beauty without the need for aggressive, high-pressure washing that can damage your render.
The Transformation: Real Results in Donegal
Take a look at this recent project. You can see how the damp climate allowed heavy red algae to streak across the render and moss to colonize the guttering.
1. The Render Rescue
Red algae (often seen as those rusty-looking streaks) is a living organism, not just dirt. Using our specialized soft-wash treatment, we don’t just “blast” it off—we treat it at the root.
2. Gutter & Fascia Refresh
Gutters are often the most neglected part of a home’s exterior. Over time, “tiger stripes” and moss buildup can make even a clean house look weathered. Our process leaves plastics looking brand new.
Why choose BioWash? Unlike traditional power washing, our BioWash system uses low pressure combined with biodegradable cleaners. This ensures your render stays intact and the algae stays away longer.
Why is Algae a Problem for Donegal Homes?
Curb Appeal: It’s the first thing people notice when they pull into your driveway.
Property Value: A clean exterior suggests a well-maintained home.
Damage Prevention: If left untreated, certain organic growths can hold moisture against your walls, leading to long-term issues.
Ready to see your home look like this again?
We cover all of Donegal, from Letterkenny and Donegal Town to Inishowen and the West. Don’t spend thousands on a painter when a professional BioWash is often all you need to bring that “new build” shine back.
Frequently Asked Questions about Algae Removal in Donegal
Why does my house have red streaks on the walls?
The red streaks/staining you see are actually a type of algae called Trentepohlia. It thrives in the damp, mild climate of Donegal. It isn’t just “dirt”; it’s a living organism that feeds on the minerals in your render and moisture from the Atlantic air.
Is power washing safe for my home’s render?
We generally advise against high-pressure power washing on modern monocouche renders (like K-Rend, Sika etc.). High pressure is way too aggressive for these types of finished plasters, often leading to “wand marks,” scarring, or even water being forced into the structure of your home. At BioWash, we use a Soft-Wash approach that uses chemistry rather than brute force to kill the algae at the root.
How long does the cleaning last?
Because our process treats the algae biologically rather than just blasting the surface, the results typically last much longer than traditional washing—often up to 3-4 years longer. The biocidal treatment kills the root spores leaveing a residual protection on the surface that inhibits new growth.
Do I need to paint my house after the algae is removed?
In most cases, no! If you’re looking to change the colour of your property anyway, then your walls would still need to be cleaned to prevent flaking and bubbling.
Often we find that many of our Donegal clients think they need a full exterior paint job, which can cost thousands. Once we remove the red and green staining, the original color of the render is restored, saving you a significant amount of money and maintenance.
Is the BioWash process safe for my garden and pets?
Yes. We use professional-grade, biodegradable solutions. We take great care to protect surrounding vegetation and rinse everything thoroughly after the treatment to ensure your plants and pets remain safe.
I didn’t know this place existed until Kay and Mick invited me, back in July 2019, to take a look at a property they recently purchased there that didn’t always look like it does today.
Like a large percentage of properties nowadays, throughout Ireland and especially here in the North West of Donegal funghi and moss was well established on the complete exterior to the property.
Red Algae clearly visible to front, rear and sides of the property
After our initial careful assessment it was established that to bring the property back to it’s original glory it would need the following procedures to be addressed.
Roof and Capping: Moss and yellow lichen removal using Biocide
Guttering and Downpipes: Emptied and cleaned plus faded areas restored back to black
Walls: Red algae removal using Biocide
Path and Decking: Power washed and treated with Biocide
Windows: Frames and glass cleaning plus ongoing bi monthly window clean setup
Decoration: Paint window reveals, sills and chimney
The Procedure;
Roof and Cappings
We always try where possible to work from the top down so as it was in this instance we commenced with the Roof.
We will never walk on any roof to clean so working from ladders at gutter level we use scrapers to remove 90%-95% of the moss and lichen and then we will spray the whole roof using telescopic poles that allows us to get up close to the areas being sprayed thus minimises overspray.
The Bio cleanse products we use for the removal of all algae, lichen, fungi, moss and mould that cause red, green, yellow and black staining is not only completely safe to plants and animals it also has a long term residual effect which keeps the treated areas clean for longer.
Rust removal
Specific areas that needed to addressed
Guttering, Fascia, Soffits and Downpipes
Were emptied and cleaned cleaned and where the black finish had dulled to a matt grey appearance this was provided with a treatment that restores them back to a shiny black finish.
Pebbled Dash Walls and Stonework
Depending on the extent of algae infestation a liquid solution is created that is sprayed on from the bottom up and left to do its work. In some areas where it was particularly severe a second coat was applied after 3-4 hours.
Windows and Frames
Virtually all the windows still had the protective tape still in-situ and had got to a point where it had became cracked and fragile. This was removed using a special nozzle we have for the pressure washer that does no damage to the PVC frames
Paths, Decking and Kerbs
These were all cleaned using the pressure washer and then sprayed with our Bio cleanse solution that provides residual cleaning for months and years to come
Painting
Around the windows and the chimney was then given a spot of paint to give the whole property a fresh new look. I think you’ll all agree it now has fabulous kerb appeal.
If you’d like to improve the aesthetics of your own property and see what we can do for you.
Dealing with red algae on K-Rend and the removal of moss from worn tarmac, has it’s own specialist requirements
As is very common in the north west climate and especially on north and east facing exterior walls, red algae had really established itself and was very prominent on this property.
The degree of trentepohlia ( red algae) was extensive and we knew it would require a 2 phase attack to treat the problem and restore the K-Rend to its original state.
This required a softwash biocide formula that is specially prepared and is dependent on the extent of the works that need to be carried out by our fully trained professional operators.
In this instant a first coat was sprayed onto the whole property and is then rinsed off with clean water and per the request of the client the boundary retaining walls were also treated.
We then returned within 7 days to apply a seal coat that penetrates deep into the porous substrate and is not rinsed off. This solution continues to fight all future algae and funghi growth for years to come, keeping the K-Rend finish looking as it should.
BeforeAfter
Client also wanted his Tarmac areas cleaned and free from green moss
The big problem with is that it’s often cleaned repeatedly using high pressure power washers and over time the top layers of stone chipping become exposed and a haven for the build up of dirt and mosses.
The easiest solution for us would’ve been to do the same but in doing so would’ve done more damage to the drive.
Our solution was to initially kill all the moss growth and when we returned to apply the second coat to the walls we were able to brush the dead moss off the top of the tarmac and using the pressure washer with a low pressure, wide spray, rinsing nozzle we were able to remove all the dirt and mud that had collected between the stone chippings without further damage to the tarmac surface.
We have recommended to the client that he would now need to have a bitumen seal coat applied to finish and protect his drive which he’s now considering.
Around the oil tank and partition fencing was particularly dense.
Recent job completed in Carndonagh on a house with a fine dash exterior finish which had highly concentrated red algae infestation especially on the north and east facing walls. This job was performed as part of a pre-paint preparation.
As the algae present was quite heavy in places the walls were treated with environmentally friendly lightning cleanze algae treatment which has a fully biodegradable surfactant and poses no danger to plants or the environment when it is rinsed off. It is approved by both the Irish Pesticides Registration & Control Service (PCS) and UK Health & Safety Executive (HSE) for use as a softwashing biocide in Ireland and the UK.
The walls were treated with the first coat and allowed to work while we cleaned the gutters, PVC fascia and soffit before rinsing off and applying a second lower concentrate coat to kill the algae at the root and provide long lasting protection.
It is very important to treat and remove any surface algae before decorating. If the algae is left untreated and painted over it will continue to grow underneath and come through the newly decorated finish in a very short period of time.
As you can see from the before and after photographs, it turned out very well.
We use cookies to ensure that we give you the best experience on our website. If you continue to use this site we will assume that you are happy with it.
