Render cleaning: what to expect before, during and after

Before the visit

We look at the render type first, because silicone renders such as K-Rend, traditional sand and cement, painted render and pebbledash all respond a little differently. Photos of each elevation, a close-up of the worst patch and a note of anything underneath the wall, like a conservatory, pond or vegetable bed, are usually enough for a fixed written price. We also ask about cracks. Treatment gets into hairline cracks, so it is worth knowing where they are before cleaning rather than discovering them afterwards.

This guide sits under our Wall Cleaning & Softwash work, covering 20-mile radius of Plymouth.

Preparing the wall

Before any product goes on, windows, doors and electrics are protected, and planting at the foot of the wall is covered or wetted. Garden furniture and pots are moved back from the base. If there are pets, keep them inside until the rinse is finished. You do not need to be home, but an outside tap and access to every side of the house are needed.

How the softwash is applied

The biocide blend is applied at low pressure, working from the top of each elevation down so runs are always onto wall that is still to be treated. It is not a jet and it is not scrubbing; the product does the work. Where it is right for the surface, the solution is left to dwell before a gentle rinse. On heavily soiled north-facing walls the difference between treated and untreated sections is usually obvious within the visit.

Why it can look unfinished when we leave

Green algae tends to go quickly. Black algae, orange staining and lichen are different: the treatment kills them, but the dead growth takes time and rain to release from the surface. Over the following weeks it keeps lightening. A wall that looks patchy on day one is usually the sign it was treated rather than blasted, and blasting is how render gets scoured and marked. If a patch has not moved at all after a sensible time, tell us and we will look at it.

The months after

Because the growth is killed rather than scraped off, regrowth is slow and gradual. How slow depends on the wall: shade, nearby trees, orientation and exposure all affect it. The shaded side of a house under trees will always green up before a sunny, open elevation. Clearing gutters that overflow onto the wall, and cutting back shrubs touching it, both help the clean last.

When cleaning is not the answer

Some marks are not dirt. Staining from a leaking gutter will return until the leak is fixed. Painted render that is flaking is failing paint, and a clean will not bond it back. Yellowed or faded coatings are ageing of the material itself. We tell you which of these you have before quoting, so you are not paying to clean a problem that needs a repair or repaint instead.

Questions to ask any render cleaner

Ask what method they will use on your render type and why, whether they protect glazing and planting before applying anything, and what the wall should look like on the day compared with a few weeks later. Ask how they deal with hairline cracks and painted sections. A cleaner who promises an instant, spotless finish on heavily stained render by the end of the afternoon is usually planning to use more pressure than the coating should take. A clear, fixed written price after looking at the wall matters more than a quick figure over the phone.