Render is a great way to improve the appearance of a house and to provide an extra layer of external wall insulation. Sometimes though, since the rendering is on the exterior walls, it can get dirty. Things like algae growth and fungus growth can ruin the appearance for the property owners and can even damage the render. When render begins to show this organic growth, extensive discolouration or mould spores, it’s important that you clean the surface before any structural damage takes place.
There are a few ways of cleaning the render. Which one you should use largely depends on which type of render you have on your exterior walls.
Check out: How to clean a pram
Jet Washing Render
Jet washing is kind of like using a pressure washer, but the water is heated. It’s a good tool for render cleaning, and can be used on sand and cement render, acrylic render and silicone render. If you’re using a jet wash for your render cleaning, your cleaning process will look like this:
- Remove any greenery. Walls will often get organic growth on the render surface. Things like moss and ivy will grow on render surfaces and should be removed gently with a brush before you begin jet-washing render.
- Treat the render with render cleaner. This should be something that will tackle the green algae growth, stubborn stains, and anti-fungal properties. Using a suitable detergent with these properties will slow future algae growth.
- Using a mild detergent and with your jet washer on fan action rather than jet action, begin jet washing the wall on low pressure. You should be sure to only do a very light jet wash, as too much pressure can easily damage the render. Being gentle is the best way to clean render without having to worry about damaging it.
- Apply a protective coat to your render. You can purchase coatings that provide your render with a layer of hydrophobic defence, helping to prevent your freshly clean rendered surface from developing any further biological growth.
Jet washing render can be a great way to clean rendered surfaces, but it can be quite dangerous for the render. If you are worried about the state of your render, or if you’re cleaning the render in order to repair it, it may be best not to risk causing further damage and opt for a different way to clean the mould and staining away without causing further cracks. Alternatively, you could hire a professional who will know how safely to wash your walls.
Not dissimilar from jet washing, soft washing is an alternative way to clean render that uses low-pressure equipment. It is still pressure washing your render, but there is less risk of breaking your render whilst trying to clean it.
Most render can be cleaned using soft washing, as it is substantially less dangerous for the render than using a pressure washer for the render cleaning. Monocouche, coloured render, lime, acrylic, silicone, sand and cement, and even pebbledash are all fine to be cleaned with a soft wash. Just make sure you’re careful when render cleaning, no matter what you use. A soft washing cleaning process will look like this:
- Remove any moss or ivy from the wall using a brush. Gently prod the greenery away.
- Apply a fungicidal and mould removal detergent to strip your render surface of any mould and algae growth. This will make cleaning render much easier, and will prevent the mould and algae from causing any further damage and discolouration.
- Rinse your first treatment with a low-pressure washing, still making sure to be careful so that you can clean render without damaging it.
- Apply another treatment, this time just a suitable detergent to remove stains and dirt caused by weathering. Brush this onto the wall carefully, then leave for a short while.
- Once you’ve left the treatment to do its job, it’s time for render cleaning. Using the low-pressure washer, target any marks and discoloration as you clean render.
- Apply a layer to protect the clean render. This will mean that you will be able to leave it longer before doing any more render cleaning. It provides a hydrophobic coating to the clean render, preventing damp and organic growth from causing staining.
Cleaning Render By Hand
You can, of course, clean coloured render and rendered surfaces by hand too. It is less likely to cause any damage to your render, regardless of whether it is lime render or pebble dash, and usually removes the marks of algae growth and natural weathering pretty easily without having to use too much pressure washing.
To get your render clean by hand, you can simply use a soft brush and soapy water. A mild detergent of bleach solution should work to remove things like bird poo, dirt, grime, and most algae growth.
Cleaning rendered walls by hand is great, but doing an entire wall by hand can be quite tiresome, which is why most people opt for the other render cleaning processes for their rendered walls instead.
Pressure washing is generally ill-advised when it comes to cleaning render. If you must pressure wash your rendered surfaces, do so lightly. Just like with jet washing, pressure washers can blast off chunks of the render, damaging it and resulting in you needing to re-render the entire surface. This can be expensive, and is best to just avoid.
Some companies may use pressure washers to clean render, but they will likely have specialised equipment that minimises the risk of damaging the wall.