January 28, 2023

How To Clean Mould Off Render

Is the render on your property suddenly covered in mould spores? Have you been watching it steadily turn green or black recently, and now you're wondering how to tackle the new monster you're faced with?

If so, don't worry. There's always a path forward.

Whether it's mould, green algae, fungi, or other greenery, you can tackle it and leave your render with the attractive finish it once had. But if left untreated, things will only worsen.

So, just how do you clean mould off your render's surface? Well, there are a few options, and we're going to explore them together below.

Tackling Mould

Mildew, mould and other organic growth generally start to develop on rendered walls due to humid conditions, moisture, and damp surfaces. Basically, it develops simply because render is an exterior surface. Check out our post on how to clean exterior rendered walls.

And because these biological matters are, in essence, alive, the only way to tackle them is by killing them. This usually requires harsh chemicals like bleach or a residual fungicidal wash whilst cleaning render to not only kill the mould and growth, but also to clean up common dirt and messes, too.

Why Does It Develop...

The most common type of mould you'll face on the exterior of your home is black or green mould. It usually comes alongside green algae and other growth too. And you remove green algae and mould in much the same way.

Humidity, condensation, and moisture all create suitable conditions on your house exterior for this growth to form, and over long periods they can create stains and affect the overall look of your house. The solution? Try render cleaning.

Pressure Washing Cleaning Process

Pressure cleaning is just one example of how you can remove algae, dirt, and mould problems from your render and other surfaces. But this is NOT SUITABLE FOR DRY DASH FINISHES - please, remember this!

Once you're confident you can go ahead with this pressure render cleaning, follow our directions below.

1. Prep Your Walls

Start by prepping your walls. Simply running a stiff broom over the surface of your walls is a great way to loosen stubborn problems like algae, mould spores, and clumps of mud, for example.

Prepping the surface will make sure the render is ready for the spray.

2. Be Cautious Of The Pressure

High levels of pressure will cause issues. It will damage the render surface and then the render will be unable to protect your house from damp problems.

Start with the pressure washer on a fan setting using a fan tip rather than a needlepoint. This will ensure the pressure isn't too high as you clean render and it won't blast the render right off your wall.

3. Mix The Right Solution

Mixing the right solution is important too. There are many cleaners you can use whilst render cleaning that will help tackle the mould issues on your property, so shop around and pick the right products.

If you can't find mould specific products, then one cup of oxygen bleach per gallon of water is a great starting point. It will attack mould, algae, and mildew without issue. Just make sure you protect plants near where you're cleaning because they can be killed by bleach too. Check out our post if can you use bleach to clean exterior of house.

4. Test First

ALWAYS patch test an inconspicuous area first. Try out your solution and pressure to make sure it's right. The last thing you want to do is damage your property whilst cleaning.

5. Go For It

When you're happy, you can clean the render using your pressure washer and solution. Maintain the same distance from the wall as you work, keep the pressure low, and wear protective gear like goggles, overalls, and gloves.

Once the solution has been applied, you MUST wash the walls again using just water. This will prevent the chemicals in the wash from causing issues like fading your coloured render or washing away in the rain and killing the plants in your flowerbed.

Cleaning With Generic Household Cleaners

You can also take a calmer approach using a bucket, sponge, and hose that will spray your walls after cleaning away mould stains, but won't risk damaging your render.

1. Prep

As with the other method, start by using a stiff broom to get your walls ready for the wash. This is especially important when algae, mould spores, and moss are stuck on the surface. Loosen them first before washing.

2. Mix

In a bucket, mix warm water and one cup of oxygen bleach per gallon. This mixture is great at removing grease, oil, algae, and mould from all manner of surfaces.

Of course, you should test this on a small area first to ensure it isn't too strong or too weak and doesn't cause issues for your render surface.

3. Sponge

Once you're happy with the mixture, sponge it on to your walls, scrubbing as you go to remove the mould and algae. Work in sections here. Don't tackle the entire house with the mixture first because you will also need to...

4. Rinse

Before moving on to the next section of your wall, wash it with your garden hose - just water. It's low in pressure so it won't damage your render (but again, don't do this for dry dash finishes) and it will make sure your render is free of mould and the bleach solution is cleaned away.

Working With Professionals

If doing it yourself sounds a little frightening, don't worry, you can also work with professionals like our team at Wash Your Walls. We have a range of cleaning techniques available:

  • steam cleaning
  • soft wash
  • pressure washing

We can handle it for you, using a range of techniques that are suitable to different renders and will improve your mould problem with ease.

A Note On Hydrophobic Coating

Once clean, you can also add an extra layer of protection by coating your render in a hydrophobic coating which reduces damp and condensation, meaning your render isn't an environment that mould and algae can grow on at all.

Silicone render has this naturally, but adding a coating on other renders is also a good idea. Just make sure any product you pick out is suited to your render before buying.

Preventing Regrowth

Want to know how to prevent regrowth? Regular cleaning and regular maintenance is key. Your render requires regular cleaning to keep mould and mildew at bay. But there's also another way.

Soft washing. When professionals use this method, your render could be protected against organic growth for up to three years (depending on your local environment conditions).

What Now?

Want to tackle the mould yourself? Pick a day when the sun is out (even in the winter months if your mould is particularly problematic), and get to work using one of the methods above.

But if you want to have the professionals handle it for you, why not contact us today? We can't wait to work with you!

Call Us Today For a Free No Obligation Quote

0800 086 2965Contact Us

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