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How To Clean Roughcast Render

Has your once white building turned grey with unsightly spots of green algae, mould spores, or red staining? Is your roughcast/pebbledash render in need of a good clean? You might be tempted to dive in and fix it yourself with a pressure washer.


Pressure washing roughcast render might just be the biggest mistake you ever make. You might like that pebble dash effect now, but you won't like it when chunks of it are washing down the street thanks to your overzealous pressure washing....

Thankfully, we here at RenWash are roughcast cleaning experts, and we have the cleaning solutions and cleaning services to help you. And we'll tell you all about them below.

The BEST Roughcast Cleaning Process

Softwash systems are the ONLY solution to your roughcast cleaning problems. Render cleaning takes a lot of care anyway - but roughcast render especially.


Because although it's designed to handle the harshest weather, our UK weather doesn't usually blast it intensely with the force of a bull in a china shop. And that's exactly what jet washing it will do.

Soft wash is different. It uses low pressure and a mix of chemicals in a cleaning solution to gently remove biological growth and dirt for the desired effect: a render that's as good as new. For just a small fraction of the cost of replacement render.

That's why cleaning render should always be your top priority. And why roughcast cleaning NEEDS soft wash - it delivers all the rewards with none of the risk to the render itself.

It's a win-win situation.

How To Clean Roughcast Render

Why Roughcast Cleaning Is So Unique

The roughcast cleaning process is much more unique than people realise, because not only is it vulnerable to being blasted off the wall by powerful jet washing, it's also a breeding ground for biological growth and organic matter.

And things like:

  • algae
  • lichen (characterised by black staining and black marks)
  • moulds
  • moss
  • mildew
  • and fungi

all need to be killed, rather than cleaned. The low pressure and water we use also take care of the dirt and grime.

That's why a chemical solution containing different algaecides, fungicides, and bleach is necessary to treat the building's surfaces for long-lasting results. You can also check out our post about cleaning render with bleach.

The Roughcast Render

What We'll Do

So what do we do during roughcast cleaning?

1. Prep Your Walls

The first step is prepping the walls. We need to inspect the surface to see what problems you are facing. Mould needs a different cleaning solution to moss, and algae needs different solutions to lichen, for example. Check out our guide on how to clean green mould off render.

Once we've inspected the wall and render, we can decide the best cleaning solutions for render cleaning. Sometimes we may also brush the render before we rinse the property to remove any large chunks of mud, etc.


2. Mixing That Special Cleaning Solution

Roughcast cleaning is more complicated than most for softwashing because it will almost certainly have multiple organic matter problems.

So we now need to mix the perfect cleaning solution to kill the organic matter. Bleach will almost certainly be present, but algaecides won't be needed if algae isn't a problem, for example. Check out our post on how to remove green and red algae from walls.

If you want to know what's in your specific blend of cleaning solution, you can always ask us before we begin the process of applying it to your building.

3. Spray Your Walls

When spraying we ALWAYS put safety first. Your safety, our safety, and the safety of your local environment.

We spray with low pressure, and we make sure all plants and wildlife are protected from our work. The roughcast render on your building is the only surface we aim to rinse.

Once the render has been covered in our cleaning solution, we'll wait for around 10 minutes before rinsing the whole thing with water and any neutralising agents that may be necessary because of the chemicals used.

Then we clear up, taking any waste wash water with us as we do.

Got Your Own Cleaning Solutions? Think Again...

Think you can handle cleaning up your roughcast render surfaces yourself? You can try, but even the most enthusiastic DIY lovers out there have caused damage to entire buildings by misjudging their render cleaning method.

Jet washing is a no-go.

And you won't have the expertise, health and safety training, or equipment to use softwashing at home yourself.

No. It's best left to the professionals.

Why Soft Washing Is The Answer You've Been Looking For

If you choose to work with us at RenWash, we can offer a free quote with no obligations today. We always price reasonably, because the last thing we want you to do is waste time and money painting over the problem with paint (which doesn't fix the issue), when all you needed was a good clean.

And there are even more reasons why you should work with us:

Soft Washing

No Risk

Your roughcast render won't be damaged. Guaranteed.

No Fuss

We take care of the whole thing for you. No money or time wasted.

Excellent Results

Delivering amazing results each and every time is just what we do. Always.


Nobody knows how to clean their roughcast render until they need to know. Except, thanks to us, you don't need to know, because we already do!

If you have a roughcast render that needs cleaning, then contact RenWash today. We can't wait to transform your render and show it off at its best once more!


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