Cleaning Rendered Walls


Cleaning rendered walls can make a dramatic difference to the appearance of a building. Whether it is a dwelling or school, has coloured or painted render, pebble dash or roughcasting, the walls will tend to suffer in our damp climate or may have a whisky storage bond nearby that makes walls and window sills go black.

Cleaning Rendered Walls

Green algae and just general weathering and atmospheric pollution are other factors to consider that can turn beautiful light shades and colours of render black or green and unsightly.

The traditional answer is generally applying a biocide-based chemical to kill the spores and algae on the render – often marketed as ‘softwashing’ – and involving sodium hypochlorite and then leaving the weather to wash off the dead algae.

Our Answer – RenderKleen

RenderKleen is an innovative chemical for cleaning rendered walls that works very differently to the traditional process described above. It is a non-toxic and non-hazardous aqueous cleaning solution that uses millions of nano-energy packages in the mix to penetrate under the soiling and algae to dislodge it and loosen it off.

The contrast to the killing action described above is the revolutionary factor in why the cleaner is so safe to use and superior to many existing treatments. Biocides are disinfectants and while ‘hypo’ as it is called, is effective, it smells awful, the fall out kills plant life, ruins clothes, and who know what it does to you?!

Using RenderKleen means much quicker cleaning action and – importantly – that the process is very safe as the RenderKleen chemical is food safe as tested by Campden BRI labs and thus safe for operators and pets, lawns and even for aquatic life.

It Is Really That Safe?

Yes, it is – workers using RenderKleen for cleaning rendered walls do not even need PPE, there are no hazard warning pictograms on the packaging and the product is delivered to the site in 5 litres or 20 litres jerrycans at ready-to-use strength for convenience.

Download our k rend algae clean product SDS data sheet here.

A situation that could have been tragic with any other chemical arose recently where a contractor used a rubber tube and his mouth to try and siphon the chemical from 20-litre jerrycan into smaller bottles and got a mouthful – in his surprise he swallowed it – and, apart from a funny taste, was fine!

Cleaning Rendered Walls

How Is Best To Apply It?

This odourless cleaner solution is used in cleaning rendered walls by spraying on generously and several times or brushing or rolling on and then agitating with a semi-stiff broom or brush to help dislodge soiling, you will note a light foaming that colours with the debris.

After this leave for 5 to 10 minutes, wash off, and reapply by sprayer – we always suggest that you try a test patch first. The product is ideal as a painted render cleaner but please be aware that if the paint is in a bad state, it can easily remove some in the same way it will give algae short shrift.

Can I Use A Pressure Washer?

Yes you can – the key point is to use the pressure washer on fan setting and gently so as not to damage the render and not bring the nozzle of the lance to close and concentrate too long on a small part of the render.

Cleaning rendered walls using a pressure washer in combination with our RenderKleen chemical makes a lot of sense as it helps penetration and, as RenderKleen can often liberate A LOT of soiling, you want to wash this away rather than letting some of it dry in situ.

Interested? Please Get In Touch

If you would like SDS sheets for this remarkable product or a sample to try it out for yourself then please get in touch to discuss your needs today.

Acute Build Clean | 74 Bo’ness Road | Grangemouth | FK3 9BL

Tel: 01324 309100 | Email:

London Office | 47 Gee Street | Clerkenwell | London | EC1V 3RS

Tel: 0208 088 3703 | Email:

Non-corrosive, non-acidic, non-toxic, and non-hazardous, this chemical is certified as food safe and is safe to use near a water course.

RenderKleen 20 Litre – £80.00 + VAT Each


Cleaning rendered walls