Lifespan
How long a soft wash lasts
WestClean says a biocide treatment prevents moss regrowth for 12 to 18 months on most Irish roofs. Dirtbgone says often up to 12 months, and HP Roofing two to four years. Shade and trees shorten it.
Three Irish companies, three answers, and why.
- €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
The figures
How long each company says
| Source | How long it lasts, as they put it |
|---|---|
| WestClean, Tuam | 12 to 18 months on most Irish roofs; 6 to 9 months in the west without the post-clean biocide |
| Dirtbgone, Co. Mayo | slows regrowth significantly, often for up to 12 months |
| HP Roofing, Dublin | regrowth usually held back for two to four years; a moss clean every three to five years |
They don't agree. Shade, trees, a north-facing slope and the west's rain all shorten it. None of these is a guarantee.
What shortens it
Why it comes back sooner on some roofs
- A north-facing slope that never dries.
- Overhanging trees dropping leaves and shade.
- The west's rain: WestClean says moss can return within 6 to 9 months without a post-clean biocide.
- Old, porous concrete tiles.
- No treatment after the clean.
Keeping it clean
Making it last longer
- A biocide after every clean: it's what buys the time (HP Roofing).
- Cut back branches over the roof.
- Keep gutters clear.
- A light re-treatment rather than waiting for thick moss: Dirtbgone publishes a soft wash re-apply on a bungalow from €200 incl. VAT (Dirtbgone).
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
How often should a roof be soft washed?
HP Roofing says most Irish roofs benefit from a moss clean every three to five years; shaded roofs, more often. Some owners treat every year.
Is the result permanent?
No. Dirtbgone puts it plainly: nothing offers a permanent fix in a damp climate.
How long does the roof take to clear after a soft wash?
About a month for every year of build-up, on Dirtbgone's rule of thumb.
Keep reading
Related guides
- What soft washing isLow pressure and a biocide: what happens on the day and after.
- Soft wash roof cleaning costFour Irish price sources side by side, checked November 2026.
- Roof moss removalScraping, soft washing and treatment, and what each costs.
- Soft wash vs pressure washingWhy roofers keep high pressure off tiles and slates.
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.
- WestClean: westcleanpropertycare.ie
- Dirtbgone: dirtbgone.ie
- HP Roofing: hproofing.ie
- RoofQuote.ie: roofquote.ie