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Best Way To Clean Rendered Outside Walls

Cleaning your outside walls can feel like one helluva task, right? They're walls, for goodness sake. They're literally a structure designed to contain an entire house or business - how are you supposed to clean them effectively?

Well, if you work with RenWash, YOU don't have to.

Cleaning rendered walls is our bread and butter, because we've been cleaning render for years now (and we've never once caused structural damage to a building - which might sound obvious, but the horror stories you hear about DIY enthusiast render cleaning gone wrong is enough to make your hair stand on end).

The thing everybody gets so wrong is choosing the wrong cleaning process for the job. WE, on the other hand, know exactly which cleaning method to use when. And throughout today's post we're going to talk you through the options we offer, the best situation for using each one, and how we can help if you're looking for somebody to come and clean your render for you.

Suitable Cleaning Methods For Cleaning Render

There are multiple cleaning options open to you when render cleaning, but the two that are BEST suited to the job are:

  • pressure washing/jet washing
  • soft washing

And we can't stress enough how important it is that the pros do this for you. No, we're not hard selling here - we're simply stating the facts:

DIY enthusiasts damage their render FAR MORE OFTEN than professionals do.


Because they get the pressure of their power washer wrong, and when that happens, it's bye-bye render, hello exposed brick walls. And that leads to damp and moisture problems in the house, structural damage to the building, and ultimately one of the largest bills you'll face for your house.

Call in the pros, though, and you just pay for the cleaning service that's best suited to the task. And we'll decide if that's pressure washing or soft washing (or something else, but more on that later).

Best Way To Clean Rendered Outside Walls

Pressure Washing Explained

Pressure washing render cleaning simply involves the use of a pressure wash with a mixture of generic household cleaners and hot water (using a fan tip, usually). This blasts the render surfaces clean.


The pressure washer must be on the lowest setting, and used a good distance from the render. Or else you will just rip off that render.

When a professional uses it at a low pressure, this type of cleaning can be effective for render cleaning. So long as it's done extremely carefully.

The Pressure Washing

When Is Jet Washing Best Used?

Pressure cleaning with a jet wash is great for removing grease or dirt from the outside of a property. Generic messes are fine to be tackled with pressure wash.

In most cases, a stiff broom or brush to loosen any clumps of dirt followed by mild detergent and warm water is enough to remove even stubborn stains from a rendered area.

This approach is low maintenance and quick for pros like us to do.

However, it isn't advisable for dry dash finishes and may be unsuitable for other types of render such as pebble dash, which may be more susceptible to damage.

Jet Wash 4

Can I Pressure Washer Rendered Walls Myself?

We wouldn't recommend it.

With the proper training and careful approach, it's possible. But if you're inexperienced, the chances are you'll damage the render on your house or commercial building.

Jet washing, even with the right equipment, is best used on solid surfaces like concrete, where there is no risk of damage.

Problems With This Cleaning Process

There are several problems you MIGHT face with render cleaning using this approach:

You Might Damage Your Entire Wall...

This is a genuine problem for the inexperienced.

We've said enough about this already, though. So let's move on...

It Takes An Expert

Not only does it take an expert to use the power washer in a way that is safe and causes no damage, but it takes an expert to decide if it's right for the render and right for the messes that need to be cleaned up.

It Won't Kill Algae Growth, Mould Growth, And Other Greenery/Organic Growth

Talking of knowing if it's right for the messes or not, pressure wash is best used for dirt and generic messes.

But green algae, red algae, mildew, mould, fungus growth, lichen, and other organic growth won't be dealt with by just using water and pressure. You can check out our post how to remove green and red algae from walls.

These messes call for harsh chemicals like residual fungicidal wash, algaecides, surfactants, and bleach solution. Only this will kill the growths and lead to long periods of time without them coming back. Check out our post on cleaning render with bleach.

Mould On Wall

Soft Washing Explained

Soft washing is the best technique to help remove green algae, mould spores, and all other biological growths from your exterior walls.

Here, a low pressure cleaning device is used with a mix of chemicals to spray the outside of your house with a coating that will gently clean render, but in a quick and effective way.

When Is Soft Wash Best Used?

Soft washing can handle:

  • algae (both green and red algae)
  • mould
  • mildew
  • lichen
  • fungi
  • dirt
  • organic matter

If your render has obvious signs of biological growth problems, then the ONLY way to deal with it is with soft washing. And it deals with generic messes too.

Soft Washing 2

Can I Soft Wash Rendered Walls Myself?

To start cleaning render using soft wash, you'd have to be an experienced and trained professional because getting the mix of chemicals right to clean render isn't easy. For an attractive finish, you need to know which cleaning products are needed to get the job done.

In addition, it requires specialist equipment, so it's actually just far more cost effective to hire somebody like RenWash to do the job for you.

No fuss results, delivered fast.

Problems With This Cleaning Process

That's not to say soft washing is the answer to all your prayers:

Experts ONLY Here Folks...

Because it's more complex than simply jet washing, you'd have to get specialist equipment and training to clean your exterior walls using this method yourself.

A mission most won't bother taking on.

That means relying on companies like ours to maintain and protect your render from future biological growth problems and to keep those surfaces clean.

May Need Additional Support (e.g. Steam Cleaning Render)

Sometimes the more stubborn problems require more than just the soft wash. Here, steam cleaning may be necessary to remove stains to see the best results.

And that can mean more money spent.

This often happens when we clean coloured render because an additional steam clean is usually necessary during the render cleaning process in order to restore the colour of the render.

If you have a monocouche render with a hydrophobic coating, though, the colour is usually preserved quite well. Each job is different.

Alternative Cleaning Services RenWash Offers

Although the following two cleaning services aren't offered for render cleaning exterior walls often by themselves, they are worth knowing about because they are sometimes necessary.

Two cleaning services we offer that may come in handy are:

  • DOFF steam cleaning
  • TORC cleaning

DOFF Steam Cleaning Explained

DOFF steam cleaning may be used on exterior walls to support a gentle but effective way of cleaning the surfaces of render.

Here, steam is used at an incredibly high temperature to remove even the most stubborn messes like graffiti, spray paint, or regular paint.

No chemicals are used, and it's a great natural way to remove mess from a surface. But not all render can handle such high temperatures.

If we feel DOFF steam cleaning is right for you, then we will discuss this when you contact us. If you have painted render though, then this isn't usually an option since the steam will just strip the painting from your property.

Doff Steam Cleaning

TORC Cleaning Explained

We would RARELY recommend cleaning render with TORC cleaning because it can strip away certain types of render.

Here, an aggregate substrate mixed with low pressure air and a small dash of water (for just a little moisture) is used to remove any coating of dirt, grime, or mess from a solid surface. The aggregate substrate essentially blasts away the mess in a safe, but thorough way.

This cleaning method is often used on heritage sites and listed buildings that require a great deal of care during restoration.

It may sometimes be suitable for render cleaning, but not often, because the substrate can blast the render away.

TORC Cleaning 1

The BEST Way To Clean Render

So is there a BEST way to clean render?

Well, hiring professionals is the best way. But if you're looking for one best method, there isn't one.

All four of the methods we've discussed today are brilliant at cleaning messes from an exterior surface of a property - and in certain circumstances ALL are useful for render cleaning too.

What you really need to ask yourself is what each cleaning method is best at:

  • Pressure washing: Power washing solids surfaces, and occasionally blasting dirt from render EXTREMELY carefully...
  • Soft washing: Attacking organic matter and dirt - BEST for render cleaning
  • DOFF steam cleaning: Gentle steam cleaning with FAST results - great on a range of surfaces, but not ideal for painted ones
  • TORC cleaning: Restoring heritage sites and listed buildings - occasionally suited to render cleaning a property depending on render type, thickness, and the ultimate goal for the cleanup

For your render needs, though, we're much more likely to employ pressure or soft washing techniques.

How Often Should You Clean Your Exterior Walls?

We'll finish on an important question, because we know many of you will feel a little nervous about paying for someone to keep your render clean. And for good reason - it's a cost many of us don't expect.

But here at RenWash, we're not trying to pressure you into a weekly clean just to line our pockets. We only want to work for you when it's necessary to help transform your house and curb appeal.

So how often should we be coming to clean your house render?

Really, only as often as necessary. Sometimes you'll find your house or commercial property looks great for even a couple of years after cleaning. (If it does, don't waste your money - we'll always be here when you want us).

Some properties might require work every couple of months - it depends on your environment and how dirty it gets.

Here's a useful tip, though:

If You Feel Like Your Render Needs Cleaning, It Probably Does.

So call us when you and your property are ready!

Exterior Wall

Your Next Steps

Now what?

Well, if you think your render needs cleaning but you're not sure which method is best, just contact us today.

A member of our awesome team will be able to advise, and we'll be able to book you in for an appointment as soon as you're ready to go ahead.

Oh, and any quotes we give are free and no obligation too.

No pressure. Just quality results.



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