January 28, 2023

How To Clean Exterior Rendered Walls

To achieve great results when render cleaning, you need to pick the right cleaning method for the right render. Get it wrong, and there could be dire consequences.

Despite your walls being covered in dirt, mould, algae, fungi, lichen, and other organic growth issues, PAUSE. Don't rush into pressure washing your render to remove stains, because you won't just remove the stains, but the entire render surface too.

Below, we'll talk you through the main ways to clean your exterior walls before looking at the very best option for different types of renders.

Ready to find out more?

Then join us below.

Cleaning Exterior Walls Options

When you want to clean render, it's important that you think about how to protect your render first. Without expert knowledge, it's easy to cause damage to buildings and properties by choosing the wrong method that just isn't suitable for the building.

So, what are the main options open to you?

Not sure what those render cleaning methods for exterior walls are? Don't worry, we'll break it down below.

Soft Wash Cleaning Process

A soft wash cleaning system simply uses a water, biocide and bleach solution to gently remove organic growth like algae, mould, moss, etc., from render. It will clean render in a non-abrasive way, with low pressure and a gentle spray that is perfect for thinner renders that could be blasted away with high pressures. Check out our post if can you use bleach to clean exterior of house.

Sometimes a stiff broom or brush is required to first dislodge the dirt and mess caused by natural weathering before a coating of soft wash can be applied to the surface to start the render clean.

Jet Washing Process

Perhaps most popularly chosen when you clean driveways, jet washing is another approach that can be used on a property to clean render. However, if the surface is delicate, this option SHOULD NOT BE USED!

Why? Because jet washing simply relies on high pressure and water to remove messes. If render is worn, cracking, or just thin, jet washing can destroy the colour and possibly destroy the complete render altogether.

It also shouldn't be used on render covered in painting, because the paint would be blasted away too.

If there is any sign that the render would be damaged by the process, an alternative cleaning system must be found.

Steam Cleaning

A steam clean differs from the previous two methods because it doesn't rely on moisture or spray to clean the outside of the building. Instead, steam clean is able to create an effective steam that blasts away messes gently.

It's important to note that only a little water is used in this approach, mostly it's high heat and steam that will remove messes from your wall.

Of course, not all renders can withstand this type of heat, so the building and render type should be taken into account before coating it with steam.

TORC Cleaning Process

TORC is a system that uses water, air, and a fine inert granulate that's able to remove algae, staining, and messes from a wall by creating a vortex of swirling mixture in the TORC equipment to then target the residue on the wall.

Again, this wouldn't be suitable for a painted wall, because you would have to sit back and watch the paint be blasted away as the granulate removed it entirely.

Cleaning Render Effectively

To maintain your render effectively, you need to choose the right option for your render. Yes, some are more cost effective, and yes, some might seem easier to carry out, but you must choose the render cleaning method that's right for the surfaces you're dealing with.

Let's take a look at different types of render below that you might have on your house, so you can choose the right method to help remove stains, dirt, oil, mould, algae, etc., from the exterior surface of your building. You can also check out our article on how do you remove algae from render.

Coloured Rendering

For coloured rendering, a calm approach like soft washing is best. It will ensure the colour is left intact and doesn't become damaged. Work with professionals, like us here at Wash Your Walls, and they'll be able to advise about the rest of the procedure because you may need a less strong solution.

In addition, you might need specific products like algaecides to tackle algae, fungicides to tackle fungi, and so on.

Professionals will be able to determine the best solution to help protect your render surfaces.


Typically, the best way to clean monocouche is with high heated steam - above 150 degrees usually. That's why it's really important that professional cleaners handle a high heat steam clean, because those high temperatures are enough to potentially crack and smash windows if you miss.

Besides, specialist equipment is required, that we're sure you don't have lying around the house.


Soft washing is great for tyrolean, because the texture of a tyrolean coating can be damaged by stronger approaches. Heat isn't always advised here, either. A soft washing approach using a tailored solution is a great way to protect the tyrolean render on your house.


Cement render alone can usually be tackled with a gentle pressure wash, but if you have paint, STOP. You have to watch what you're doing when paint's involved because it can accidentally be removed.

When paint's involved, it's best to consult the professionals to see what's best.


INCREDIBLY low pressure washing (we're talking fan setting) is best for silicone. It's hydrophobic, so it's naturally protected against organic growth, but general messes can still occur.

A sponge and bucket is fine if you're doing it yourself, but if you want a thorough coating, call in the pros.


Acrylic render should be treated much the same as silicone - low pressure jet washing with a slow stream of water to ensure it doesn't get damaged will be fine. Biological growth is quite common with acrylic renders though, so your house might require a soft wash coating too.

A stiff brush first will also dislodge dirt from larger grain sizes of acrylic render before washing too.


Lime render, though complicated because of its ability to 'breathe', isn't so difficult when cleaning. A soft wash approach is recommended, and a 'lime-wash' solution can be created to help clean up the outside of your property with ease.

You're free to try to wash lime render yourself, but getting the soft wash solution right is vital.

We'd recommend relying on professionals like us.

How Do You Clean Concrete Render?

You can jet wash concrete render without issue, so long as you use a low setting. A steam cleaning is also a great option if the concrete render is fully intact. Any sign of damage will need to be thought about carefully before an effective approach can be chosen.

All Other Types Of Render

Deciding between TORC, steam, soft, and jet wash is a decision best left to professionals because each building needs to be thought about on a case-by-case basis. Things like:

  • render type
  • render condition
  • listed vs not listed building
  • available systems

all need to be thought about before a sensible decision can be made.

Is It Necessary To Clean The Entire Wall?

Even if only a small section of your exterior wall is affected by dirt, algae, and other biological growth, we would still advise cleaning the entire wall.


Because if one section is affected, it's likely the whole wall is, it just isn't showing the issues yet. Besides, a soft washing approach will also help prevent regrowth of biological matter in the future, so treating your entire wall (and even entire property) makes a lot of sense.

What To Do Next

If you're in any doubt at all, seek advice. The difference between successfully clean render on your property and no render being left on your wall could be as simple as opting for pressure washing when a soft wash would have been better.

Here at Wash Your Walls, we offer a range of services to help clean your exterior walls, removing staining and cleaning up your property successfully as we go. And we can even advise about the best cleaning system to use on your property.

So, contact us today, and you won't have to worry about cleaning your exterior walls yourself - because we have all the equipment and know-how to deliver the best results every time!

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