The method
What soft washing is
Soft washing is cleaning a roof with a biocide solution put on at low pressure, often from the ground or the roof edge with a pole. It kills moss, algae and lichen at the root, and the dead growth dries and washes off with the rain over the following weeks (Dirtbgone).
What's used, what happens on the day, and what to expect after.
- €900 to €2,500soft wash roof cleaning with treatment, RoofQuote.ie's national range
- €400 to €700a standard three-bed with moderate moss, HP Roofing, Dublin
- No high pressureon tiles or slates: low pressure and a biocide (WestClean)
- 13.5% VATon cleaning a house, the reduced rate, if the company is registered (Revenue)
FreeNo obligationOne company rings you, not fiveNothing booked until you say yes
Before and after
Real roofs, real photos
Real roof cleaning jobs, shared by the Irish company that did them. Each says where it was. The company we pass you to may not be the one that did these.
Before
After
Before
After
Before
AfterHow it works
Killing it, not blasting it
Dirtbgone, a Mayo company, describes it step by step:
- The biocide is mixed with water and applied at low pressure, usually with a pole and brush system.
- It soaks into the moss and algae cushions down to the roots.
- Cell walls start breaking down within hours, and visible change can show within a day.
- The dead moss dries out over the following weeks and washes off with the rain.
WestClean calls it the low-pressure application of a biodegradable biocide that kills moss, lichen and algae at the root.
On the day
What happens on the day
- A look first: the pitch, how much moss, and access, trees and power lines (Dirtbgone).
- Thick moss scraped off by hand, where it's needed (RoofQuote.ie).
- The biocide applied evenly over the roof: a couple of hours to a full day, depending on size (Dirtbgone).
- Gutters cleared of what came off, and the ground tidied.
After
How the roof clears
It isn't instant. Dirtbgone's rule of thumb is about a month of clearing for every year the roof has gone untreated, so a ten-year build-up can take close to a year to wash away fully. Rain does the rinsing. Some companies rinse at low pressure on the day for a quicker result.
What it's for
What a soft wash does and doesn't do
It suits algae, staining and lighter growth, and slows regrowth (RoofQuote.ie). It doesn't fix broken tiles, failed felt or bad flashings: cleaning removes moss and dirt and repairs nothing (RoofQuote.ie).
See it first
Your roof clean, on your own photo
Take a photo of the house from the road and see the roof without the moss and streaks before anyone quotes. Free, in under a minute.
- Upload a photo, or answer 4 questions.
- We pass it to one company that covers your county.
- They ring you with a price.
Preview of your photo, not a guarantee. Your photo goes to Google's Gemini service to make the picture and isn't kept.
A photo that works
- Daylight, from the footpath or the garden.
- The whole roof in the shot, ridge to gutter.
- The worst side: usually the north-facing slope.
- Never go up on the roof to take it.
Free quote
Get a soft wash price in 4 taps
Tap what you need and leave your number. It goes to one roof cleaning company that covers your county, and they ring you back with a price, often from a photo.
FAQ
Questions people ask
What chemical is used in a soft wash?
A biocide mixed with water. Ask the company which product it uses and how it protects plants and ponds below.
Does someone have to walk on the roof?
Rarely, for a soft wash: it's usually applied from the ground or the roof edge (Dirtbgone). Scraping thick moss does mean working on the roof.
How soon will the roof look clean?
Some change within a day; full clearing takes weeks to months, about a month per year of growth (Dirtbgone).
Is soft washing the same as roof cleaning?
It's one way to clean a roof. The others are scraping by hand and, on sound modern tiles only, pressure washing.
Keep reading
Related guides
- Soft wash vs pressure washingWhy roofers keep high pressure off tiles and slates.
- How long it lasts6 months to 4 years, depending on who you ask and the roof.
- Soft wash roof cleaning costFour Irish price sources side by side, checked November 2026.
- Safe for tiles and slates?Concrete tiles, natural slate, solar panels and plants.
Where these numbers come from (1 public source, checked 3 November 2026)
Sources (4)
Prices and facts on this page were checked against these published pages. We are not connected to these businesses.
- Dirtbgone: dirtbgone.ie
- RoofQuote.ie: roofquote.ie
- HP Roofing: hproofing.ie
- WestClean: westcleanpropertycare.ie