Render Cleaning: The Complete Guide

Why render needs different treatment to brick

Render is essentially a coating applied over blockwork or brick, and unlike solid masonry, it can be relatively thin, especially on older properties, and vulnerable to cracking or water penetration if the coating is compromised. High-pressure washing directly on render risks forcing water behind the surface through hairline cracks, which can lead to damp problems well after the cleaning itself looks finished and dry.

Different render types also behave differently under pressure and chemical treatment. Traditional sand-and-cement render and pebbledash are generally more forgiving but can still be damaged by excessive pressure, while modern thin-coat silicone renders and K-rend systems are specifically designed with manufacturer guidance that often explicitly rules out pressure washing in favour of soft washing.

Soft washing versus steam cleaning for render

Soft washing is the standard approach for the vast majority of render cleaning jobs: a biocide or gentle detergent solution applied at low pressure, left to dwell and work on algae, moss and grime, then rinsed off gently. It's effective, low risk to the render surface, and the biocide treatment continues working after the visit, slowing how quickly growth returns.

Steam cleaning is useful for specific problem areas, particularly stubborn black algae staining or ingrained dirt in textured pebbledash that a standard soft wash doesn't fully lift, using heat rather than pressure or heavy chemical treatment to break down grime. It's often used as a targeted finishing step on particularly bad patches rather than as the sole method across a whole elevation.

What render cleaning typically costs

Render cleaning is usually priced by property size or elevation, with a typical semi-detached house running from around £300 to £600 for a full soft wash treatment of the render, and larger detached properties or those with particularly heavy black algae staining running higher. Combining render cleaning with roof cleaning or gutter clearing on the same visit often works out more cost-effective than booking them separately.

Beware quotes that seem very cheap relative to others, since a genuine soft wash treatment takes real dwell time for the biocide to work properly, and a rushed job that skips this step tends to leave staining that returns within months rather than years.

Common render cleaning mistakes

The most common and costly mistake is pressure washing render, particularly modern thin-coat systems, which can crack the surface, force water behind the coating, or strip texture unevenly leaving a patchy finish. Skipping biocide treatment entirely and relying on rinsing alone also tends to give disappointing, short-lived results, since the algae and moss aren't actually killed at the root, just temporarily washed off the surface.