How to clean coloured render safely
The main risk with coloured render is not the staining — it is ending up with a wall that is clean in patches, or lighter where someone worked too close.
Knowing which kind of render you have decides the whole approach, so it is the first thing to establish.
Which render do you have?
- Through-coloured silicone render such as K-Rend — colour runs through the material, surface is textured
- Painted render — a coating over the top, which can chalk, flake or wear at edges
- Traditional sand-and-cement render — often painted, sometimes bare, more absorbent
- Pebbledash and roughcast — heavily textured and very good at holding growth
Rules that apply to all of them
- Test a small, less visible area before treating a whole elevation
- Clean a full elevation at a time to avoid tide marks part-way down a wall
- Keep pressure low — force is what causes irreversible damage
- Take care around planting, borders, windows, frames and seals
- Check gutters and downpipes, as leaks are the usual cause of repeat staining
Where the differences matter
On painted render, a wall that is already flaking will not be improved by cleaning — the coating will simply come away in some places and not others. That is a repainting job, not a cleaning one.
On pebbledash and roughcast, growth sits deep in the texture and usually needs longer dwell time rather than more pressure. On through-coloured render, protecting the surface texture is what protects the appearance long term.
Cleaning it yourself
Ground-floor sections on a sound wall are within reach for a careful homeowner working at low pressure. What is worth thinking twice about is gable heights, ladder work, and anything where a mistake shows permanently across a large elevation.
If you are unsure which render you have, send a close-up photograph along with a shot of the full elevation and you will get a straight answer either way.
Want it looked at properly?
Send a few photographs of the elevation along with the address, and Rob will tell you what can realistically be improved, what it will cost and when it can be done.