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How To Remove Algae From Rendered Walls

How To Remove Algae From Rendered Walls

Newly-rendered walls look beautiful, don't they? They're crisp and clean, with bright colours and appealing textures, which is why render is such a popular building material.

However, if you're not careful, they can start to look pretty grim: spores, pollen and bacteria accumulate, and organic growth becomes a problem. Red algae, green algae and black algae leave walls looking dirty and neglected.

This is bad news for several reasons:

  • It may affect the value of your property as it reduces kerb appeal
  • It makes the local area look run down
  • Potential customers and clients could be put off from visiting commercial properties
  • It damages the surface coating if left untreated

What Causes Algae Growth?

Algae can grow just about anywhere. Oddly enough, lower pollution levels have led to an increase in algae! Airborne spores settle on rendered walls (particularly on the north side of a building) which is a perfect host because of the tiny pores and moisture that provide ideal conditions for algae to thrive.

After a while, it starts to affect the surface, causing pitting and tiny cracks. And although this won't be serious, it will make it look unsightly and could result in costly repairs.

Algae on Walls 1

What Can You Do About It?

As experts in cleaning rendered walls, Right Wash is well-placed to offer advice on removing algae. Our specialist team has extensive experience in the removal of algae growth from exterior walls and roof tiles.

With this in mind, here's some advice on the issue:

Under Pressure

Many homeowners automatically reach for a pressure washer, but this could be a mistake. While there's no doubt that it blasts away the algae effectively, it's likely that you'll damage the render surface. Even if it isn't immediately apparent, water forces its way into the render matrix. This expands when it freezes, causing cracks in the surface.

Also, it's likely that the algae will return anyway!

Pressure Washing 2

The Soft Approach

Soft washing is a more effective method, and this is probably the one the team at Right Wash uses the most.

A soft wash involves using a pressure washer on a low pressure setting along with a suitable cleaning solution. Several passes are usually required to loosen the dirt and algae and wash it away. A final spray rinses the surface clean, leaving it looking as if it had just been applied.

Red, black or green algae stains can sometimes be stubborn, so it's a good idea to use a brush to gently scrub the surfaces. Heavy red algae stains can be difficult to shift and they look like rust. Again, it may be necessary to repeat the cleaning process to remove red stains completely. Never use excessive force, or you may damage the render!

For light staining, simply spray on a branded cleaning solution and let the weather wash it clean.

Avoid Using Harsh Chemicals

While it might seem to make sense to use a more powerful cleaner, household bleach (sodium hypochlorite) is best avoided, even for heavy red algae staining. If you do use this option, make sure it is well diluted and where appropriate PPE.

Some websites suggest making a cocktail of bleach, household cleaners and powdered laundry detergent. While this is probably safe and may remove stains, it isn't particularly healthy if you breathe the fumes and it may be too harsh for the render.

At Right Wash, we use biodegradable solutions that are safe and effective.


Biocides & Fungicides

It's one thing to remove algae, but quite another to prevent regrowth. Unless you clean your wall render thoroughly, microscopic spores will remain and you'll soon have the same problem as it begins to grow again.

That's why we incorporate fungicides and biocides into our soft wash cleaning process, as this is highly effective in preventing any kind of vegetation or organic growth from taking root in your wall surfaces again.

Right Wash Professional Render Cleaning

Although many people like to attempt this job themselves, removing algae and preventing further organic growth isn't as easy as it might sound, especially if it has been left untouched for several years.

Also, you'll need to reach those upper levels, which means standing at the top of a ladder while working, which is a potentially hazardous process.

For the best possible results, protect your rendered walls by calling Right Wash today. We'll take the hassle and strain out of removing algae and unsightly stains, leaving your walls looking bright and clean once again.

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