Roof Cleaning | Mayo & the Northwest
Roof Cleaning
Moss Removal - Soft Wash Specialists
The north face of your roof is coated in thick green moss. Black streaks of algae are spreading across the south slope. Lichen is gripping the tiles so hard it’s starting to lift the surface. And every damp Atlantic winter makes it worse. We’re North West Property Solutions, based in Castlebar, and we specialise in professional roof cleaning using soft wash techniques – not high-pressure jetting that can damage tiles, blast out pointing, and force water under the felt. Our approach kills moss, algae, and lichen at the root, then applies a preservation treatment that stops them coming back for years. A clean roof isn’t just about kerb appeal – it’s about protecting the most expensive structure on your property from slow, steady, biological damage.
- Fully Insured & Guaranteed
- Based in Castlebar, Co. Mayo
Trusted property maintanence & roofers across Mayo, Sligo, Leitrim & Roscommon
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What Goes Wrong on Irish Roofs
Moss, algae, and lichen are not just cosmetic problems. They actively damage your roof, and the damp Irish climate gives them ideal growing conditions year-round.
Complete Roof Cleaning Solutions
Moss Growth on North-Facing Slopes
Thick cushions of moss trap water against the tile surface. The moss roots work into the grain of concrete tiles, gradually breaking down the surface layer. In winter, trapped water freezes and expands by roughly 9%, cracking tiles from the surface down. Over several seasons, what started as a green patch becomes a structural problem.
Lichen Colonisation
Lichen forms crusty, pale grey or orange circular patches on roof tiles. Unlike moss, which sits on the surface, lichen physically bonds to the tile – it secretes organic acids that etch into the surface and anchors itself deep into the microscopic pores of the material. Over years, this permanently scars and weakens tiles. Lichen is the most difficult growth to remove and the most damaging if left untreated.
Gutter Blockage from Moss Debris
Moss and organic debris washed off the roof clog the gutters. Blocked gutters overflow, saturating the fascia boards and the wall below. In winter, standing water in blocked gutters freezes and the weight pulls fixings out of the fascia. What starts as a roof cleaning job often reveals a guttering problem underneath.
Complete Chimneys Cleaning Solutions
Black Algae Streaking
Algae spreads across the tiles as a dark, streaky coating – most visible on south-facing slopes where the contrast with cleaner tiles is starkest. It holds moisture against the tile surface continuously, accelerating the breakdown of the tile’s protective factory coating. Concrete tiles lose their colour finish; natural slates develop surface pitting and erosion.
Blocked Water Channels Between Tiles
Moss builds up between tile overlaps and clogs the drainage channels that guide rainwater down the roof. Water backs up behind the moss and seeps sideways under the tiles, soaking into the batten space. Over time, the battens rot and the underlay deteriorates. Eventually you get a leak that has nothing to do with a broken tile – it’s a drainage failure caused by moss.
Accelerated Tile Ageing
Concrete roof tiles have a design life of 40 to 60 years. Biological growth – moss, algae, and lichen working together – can cut that lifespan significantly. The surface coating breaks down faster, the tile body absorbs more water, and the freeze-thaw cycle does the rest. A twenty-year-old roof with heavy moss growth often looks and performs like a forty-year-old roof.
Our Roof Cleaning & Preservation Services
From a light clean to a full preservation treatment, we offer a complete range of roof care services across Mayo, Sligo, Leitrim, and Roscommon. Every job starts with a free roof-level inspection so you know exactly what your roof needs and what it will cost.
Moss Removal
We remove moss from your roof using soft-wash biocides applied at low pressure – never a jet wash. The biocide penetrates deep into the moss cushions and kills them at the root, right down into the pores of the tile. Over the following weeks, the dead moss dries out, loosens its grip, and washes off naturally with rain. No scraping, no wire brushing, no risk of lifting or cracking tiles. Once the moss is gone, the tile surface underneath is intact and undamaged.
Common issues
- Low-pressure biocide application
- Full roof coverage - all slopes
- Root-level moss kill
- Natural rain rinse - no scraping
Roof Preservation Treatment
Once your roof is clean, we apply a clear, penetrating biocide treatment that soaks into the tile surface. This preservation treatment prevents moss, algae, and lichen spores from taking hold again. It doesn’t change the colour or appearance of your tiles – it works at a microscopic level, creating a surface that biological growth can’t bond to. One application typically provides five to seven years of protection in Irish conditions. It’s the difference between cleaning your roof now and cleaning it again in two years.
What’s included
- Clear penetrating biocide application
- Invisible - no colour change
- 5-7 year protection in Irish conditions
- Prevents spore adhesion
Roof Coating
After cleaning, we can apply a clear, breathable roof coating that adds an extra layer of protection to your tiles. This isn’t a paint – it’s a penetrating sealant that bonds with the tile surface, reducing water absorption and improving resistance to freeze-thaw damage. It’s particularly useful on older concrete tiles where the original factory coating has worn thin, and on natural slate roofs where surface erosion has started to create micro-fissures that hold water. The coating is completely invisible once dry – your roof looks clean and natural, not painted.
What’s included
- Clear breathable penetrating sealant
- Reduces water absorption
- Improves freeze-thaw resistance
- Invisible once dry
Soft Wash Roof Cleaning
Soft washing is the method we use for all roof cleaning work. Low-pressure application of a biodegradable cleaning solution that kills moss, algae, lichen, and bacteria on contact. The solution is applied using a pump sprayer at pressures similar to a garden hose – there is no high-pressure jet involved. This means no water is forced under tiles, no pointing is blasted out of ridges and verges, and no tile surface is stripped of its protective coating. Soft washing is the industry standard for modern roof cleaning, and it’s the only method we use.
Common issues
- Low-pressure pump sprayer application
- Biodegradable cleaning solution
- Kills moss, algae, lichen, bacteria
- Zero mechanical damage to tiles
Algae & Lichen Treatment
Algae and lichen require a stronger treatment formulation than moss alone. We use a targeted biocide that breaks down the cellular structure of algae and the chemical bond that lichen uses to anchor itself to the tile. The treatment is applied across the full roof area and left to work over several weeks. For heavy lichen infestations – the kind that has likely been growing for decades – a second application may be needed to fully clear the most stubborn patches. Once treated, the roof surface returns to its original colour.
What’s included
- Targeted biocide formulation
- Full roof area application
- Breaks cellular algae structure
- Restores original tile colour
Annual Maintenance Plan
For properties where moss and algae are a persistent problem surrounded by trees, in deeply shaded locations, or in particularly damp microclimates near the coast we offer an annual maintenance plan. Once a year we inspect the roof, apply a maintenance-dose biocide treatment to any areas showing early signs of regrowth, clear the gutters of debris, and check the overall condition of the roof covering. It’s a low cost way to stay ahead of biological growth before it becomes a problem that needs a full clean.
What’s included
- Annual roof inspection
- Maintenance-dose biocide treatment
- Gutter clearance
- Roof condition check
Our Services
Have more questions?
Contact our roofing experts today to schedule a roof inspection and receive a detailed estimate for your installation project.
AREAS WE SERVE
Roof Cleaning Services Across the Northwest
We’re based in Castlebar, Co. Mayo, and we provide professional roof cleaning and preservation across the full northwest region. If your county is listed below, we cover it. If you’re just outside the area, call anyway – we regularly travel for larger roof cleaning jobs.
County Mayo
Castlebar, Westport, Ballina, Claremorris, Ballinrobe, Swinford, Ballyhaunis, Knock, Kiltimagh, Foxford, Newport, Louisburgh, Belmullet, Achill, Crossmolina, Charlestown, and all surrounding rural areas.
County Roscommon
Carrick-on-Shannon, Manorhamilton, Mohill, Drumshanbo, Ballinamore, Kinlough, Dromahair, and all surrounding areas.
County Sligo
Sligo Town, Tubbercurry, Ballymote, Collooney, Strandhill, Enniscrone, Easkey, Coolaney, Grange, and all surrounding areas.
County Roscommon
Roscommon Town, Boyle, Castlerea, Ballaghaderreen, Strokestown, Elphin, Frenchpark, and all surrounding areas.
Roof Cleaning Costs - A Straight Guide
Every roof is different – size, pitch, level of biological growth, access difficulty, and whether you want preservation treatment all affect the final price. But here’s what you can expect, so you’re not going in blind.
What Affects the Price
Roof size and complexity
A standard three-bed semi has roughly 50 to 70 square metres of roof area. A detached dormer bungalow can be 120 to 180 square metres. Bigger roof means more time and more materials.
Extent of biological growth
Light moss on the north slope only is a straightforward job. Heavy moss, algae, and lichen across every roof elevation takes longer and may need additional treatment passes for full clearance.
Roof pitch and access
A steep roof at 40 degrees or more requires roof ladders and safety lines. A shallow bungalow roof can be worked from the eaves. Access difficulty directly affects the time on site.
Gutter clearance
Moss-laden gutters need clearing after the roof clean. If your gutters are heavily clogged before we start, we include a full clearance in the price as standard.
Preservation treatment
Optional but strongly recommended. Adds roughly €150 to €300 to the job depending on roof size, and gives you five to seven years of protection from regrowth.
Roof coating
An additional clear sealant applied after cleaning. Recommended for older roofs (20+ years) where the original factory coating is wearing thin and the tiles would benefit from extra protection against water absorption.
Rough Guide (Indicative Only)
| Job Type | Typical Range |
|---|---|
| Soft wash moss removal - standard three-bed semi | €350 - €550 |
| Full roof clean - moss, algae, lichen treatment (detached house) | €550 - €900 |
| Roof preservation treatment (applied after cleaning) | €150 - €300 |
| Roof coating - clear penetrating sealant (applied after cleaning) | €400 - €700 |
| Complete package - clean, preservation, gutter clearance (detached house) | €700 - €1,200 |
| Annual maintenance plan visit (single inspection + maintenance dose) | €120 - €200 per year |
These are indicative ranges only. Every roof gets a proper inspection and a fixed written quote before any work starts. Prices include VAT, materials, labour, and waste removal.
Frequently Asked Questions
Roof Cleaning Questions We Answer Every Week
Is soft washing safe for my roof tiles?
Yes. Soft washing uses low-pressure application – similar pressure to a garden hose – to apply a biodegradable cleaning solution that kills moss, algae, and lichen at the root. It’s fundamentally different from pressure washing (jet washing), which fires water at high pressure and can dislodge tiles, strip the protective surface coating from concrete tiles, blast mortar out of ridges and verges, and force water under the underlay into the roof space. Soft washing is the industry standard for professional roof cleaning, and it’s the only method we use. Your tiles stay intact, your pointing stays in place, and your roof space stays dry throughout the process.
How long does roof cleaning take?
A standard three-bed semi-detached house takes one day for the cleaning application. The moss and algae then die off over the following two to four weeks and wash away naturally with rain. We don’t need to come back to rinse or scrape – the biocide does the work and the Irish weather finishes the job. If we’re also applying preservation treatment or roof coating, that’s done on the same day. For larger detached properties with heavy growth or steep access, allow one to two days on site. We’ll give you a clear timeframe with your quote.
Will the cleaning chemicals damage my plants or garden?
No, but we take precautions regardless. The biocides we use are biodegradable and break down safely in soil. Before we start, we wet down any plants, shrubs, or grass directly below the roof edge to protect them from drips. We also cover delicate plants and fish ponds if they’re close to the working area. Once the roof treatment has dried – about an hour in normal conditions – there’s no risk to plants, pets, or children. We use professional-grade products specifically formulated for roof cleaning, applied at the correct dilution, and safe when used as directed.
How long will my roof stay clean after treatment?
With our standard soft wash cleaning, you can expect the roof to stay moss-free for three to five years in typical Irish conditions. If we apply the preservation treatment after cleaning, that extends to five to seven years of protection. Properties in particularly damp or shaded locations – surrounded by trees, at the bottom of a valley, or on a north-facing slope with no direct winter sun – may see earlier regrowth. For those properties, our annual maintenance plan is the most cost-effective approach: a single maintenance visit each year keeps moss and algae from ever getting established again.
Can you clean a roof in winter?
Yes, but we pick our days. The biocide treatment needs a window of dry weather to soak into the moss and tiles properly – typically four to six hours without rain. We monitor the forecast closely and schedule roof cleaning work for dry spells, even throughout winter. Temperature isn’t usually an issue in Ireland – our winters are mild by European standards, and the biocide works effectively down to about 2 degrees Celsius. If a booked job looks like it will be rained off, we reschedule at no cost and give you as much notice as possible.
Why does moss grow more on one side of my roof?
The north-facing slope gets the least direct sunlight in Ireland – often none at all during the winter months. That side of the roof stays damp and cool, which is ideal for moss. The south-facing slope gets the most sun, dries out faster, and is less favourable for moss – but it’s where you’ll see black algae streaking instead. Roofs shaded by trees or neighbouring buildings can have moss on all sides regardless of aspect. If your property stands on a hill with the roof exposed to the prevailing Atlantic wind and rain on one side only, that side will be persistently wetter and mossier. This is one of the most common patterns we see across the west of Ireland.
Is roof cleaning just about appearance?
No. A moss-covered roof loses kerb appeal, which matters if you’re selling. But the real problem is structural: moss holds water against the tiles continuously. That constant moisture accelerates the breakdown of the tile surface, promotes freeze-thaw damage every winter, and clogs the drainage channels between tiles, forcing water sideways into the batten cavity. Algae and lichen chemically etch into the tile material. Left untreated for years, biological growth shortens the lifespan of your roof covering – and replacing a full roof costs many times more than having it cleaned and preserved. Roof cleaning is a maintenance investment, not a cosmetic exercise.
Do you use a pressure washer on roofs?
No. We do not use pressure washers on roofs under any circumstances. Pressure washing – jet washing at high pressure – is the quickest way to damage a roof. It strips the surface coating from concrete tiles, it blasts mortar out of ridges and verges, it forces water under the tiles and into the batten cavity, and it can crack or dislodge tiles outright. A pressure-washed roof often looks clean for a few months, then the moss grows back faster than before because the tile surface has been roughened and holds water more easily. Soft washing is the professional alternative: effective at killing biological growth without any of the damage. If someone offers to clean your roof with a jet wash, say no.