Render & ETICS facade cleaning.
Algae, moss, black staining. The right method depends on your substrate and the type of soiling. On-site assessment, VCA-certified technicians, no destructive high pressure on your insulation.
📞 Call us, we’ll assess your facade Or describe your situation in writingWhy your render turns green or black.
Choosing the method isn’t a matter of preference. It depends on the colour and age of the soiling. The wrong diagnosis means a treatment that doesn’t work, or worse, a damaged substrate.
Algae, cyanobacteria
Caused by persistent damp, often on facades that get little sun (north-facing). The most common case in Belgium.
Pollution, established mould
Long-term exposure, sometimes made worse by poor drainage or gutters.
Several areas, several causes
Green north facade, black south facade. One building can need an area-by-area assessment.
This isn’t soiling
Render that rubs off when touched has reached the end of its life. No cleaning will give a lasting result. It’s time to think about renovation, and we’ll tell you so honestly.
ETICS or solid masonry, not the same treatment.
An ETICS system (external insulation under render) has a thin finish of 2 to 4 mm on insulation that is much softer than solid masonry. Pressure and mechanical action must be adapted to each substrate, never standard from one job to the next.
| Substrate | Characteristics | What it means for cleaning |
|---|---|---|
| Render on ETICS | Thin finish on soft insulation (EPS, mineral wool) | No uncontrolled direct high pressure, risk of puncturing or detachment |
| Mineral render | Lime, silicate, on solid masonry | Tolerates moderate pressure better, but is sensitive to acids and discolouration |
| Acrylic or silicone render | Solid masonry, low-porosity finish | Water resistant but holds greasy dirt, avoid strong solvents |
Two techniques, one rule. Never blind high pressure.
Our procedures draw among others on the work of Buildwise (the Belgian construction research centre), including the Clean.ETICS project on biological cleaning of insulated facades.
Gentle biochemical cleaning (softwashing)
For green, surface biological soiling, the most common case on render in Belgium. A suitable product is sprayed at very low pressure, left to work, then lightly rinsed. The chemistry kills the micro-organisms at the root, not mechanical force.
- Pressure of 2.8 to 13.8 bar, well below the 100 to 200 bar of a standard pressure washer
- No mechanical impact on the finish
- Result sometimes only visible after a few days, while the product finishes working
Controlled thermal & mechanical cleaning
For dark, ingrained or greasy soiling, or as a pre-treatment when softwashing alone isn’t enough. Hot water loosens organic dirt, moderate calibrated pressure does the rest, never exceeding the limit of the substrate.
- Pressure always tested on a small area before the full treatment
- Nozzle always moving, never held on one spot
- A good complement to a preventive water-repellent treatment
A ballpark figure before your detailed quote.
| Method | Use | Guide price |
|---|---|---|
| Gentle biochemical cleaning | Green soiling, algae, recent moss | €8 to €15 per m² |
| Controlled thermal & mechanical cleaning | Black, ingrained or greasy soiling | €12 to €22 per m² |
| Assessment & test on a small area | Before any work | Free, included in the quote |
How a job goes.
Across Wallonia, Brussels and Flanders.
Everything you need to know before you call.
Does a pressure washer damage ETICS render?
How much does render cleaning cost per m²?
Why is my render turning green or black?
My render rubs off when touched (chalking). Will cleaning fix it?
Do you use approved biocides?
How long until you see the result?
Render turning black or green?
Describe your facade to us. We’ll assess the area and the type of soiling for free.
📞 +32 476 06 02 49