A rendered exterior wall can look very smart but over the course of time it can become very dirty and discoloured thanks to algae and other natural elements, which spoils the appearance of the paintwork. So the big question is whether you should paint your render or should you clean it to bring it back to tip top condition?
In many cases cleaning it will be enough to drastically improve the appearance, but you don’t actually have to decide whether to paint it until you have done this. After all you will have to clean and prepare the surface prior to painting so a good idea is to clean your render first and then decide whether or not it requires painting afterwards.
Cleaning your render can be time consuming. In addition, some cleaning methods can leave damage and then you will have no further option but to paint it anyway or even replace the whole render itself.
So if you want to try cleaning your render, what are your options?
Jet Wash it?
A pressure washer looks as if it should be the perfect solution to cleaning your render. It is easy to use and powerful and if you have a pressure washer you will probably be looking for different ways to use it because it is fun and it gets results so quickly. Don’t do it!
Using a jet wash on render is a very bad idea. A pressure washer is far too powerful and it will leave permanent damage on the surface by loosening the render often causing some areas to actually become detached and fall off. Even if this does not happen, a pressure washer will etch the surface of the render, leaving fine grey marks. Although these may not be very noticeable and your render may look cleaner at first, once algae and natural bacteria begins to regrow this etching effect will become more prominent.
The bottom line is that pressure washing a rendered wall is a sure fire way of causing permanent damage and deterioration.
Low pressure steam clean
Low pressure steam cleaning is a good way to clean dirty and discoloured render. This type of treatment is the one used for historic buildings and is a powerful and effective way to clean rendered walls without the need of scaffolding or causing any risk of damage.
If you have a domestic steam cleaner you may be able to do the job yourself –, but as most domestic steam cleaners are usually small and hand held and primarily designed for light domestic use around the home, this type of home steam cleaner may not be up to the job . And unless you live in a bungalow or low level building a domestic steam cleaner is just not big enough to cope with large exterior areas such as walls.
A steam cleaner works by heating the water in the machine to just past boiling point forcing the pressurised steam to pass through a nozzle or a brush attachment. The vapour instantly removes any dirt or bacteria and can remove all types of surface dirt including grease in a matter of seconds.
The best way to clean your render with a low pressure steam clean is to call in a professional. There are numerous local companies offering this service and the whole clean can be carried out very quickly and efficiently.
A commercial steam cleaning service will use a powerful steam cleaning machine that can be operated from the ground via the use of extension poles and brushes to reach high areas.
The bottom line is that if you want to clean your render, calling in a professional steam cleaning service will provide the best results with the minimum hassle.
Soft wash with biocide
The appearance of render is spoilt by algae. Cleaning your render will make your property look much better but this is only a cosmetic function as algae does no damage – it just looks green and leaves unsightly black and green stains all over your render.
You can clean this off yourself by washing the render with a solution of biocide and water.
Biocide is a product that kills bacteria, mould and algae and you can apply it to the wall with a non-pressure sprayer yourself. Be careful. Biocide is toxic to wildlife and it should not enter the water system so you will need to be careful when applying to avoid local environmental damage. A biocide kills bacteria mould and algae and is extremely effective for cleaning rendered walls but there is some risk to using it.
In addition you will need some sort of sprayer with a tank where you can mix the biocide with water. You can buy chemical sprayers via Amazon and other outlets and although these are generally expensive they do not tend to come with extendible poles that you would need to reach the top of the average sized house.
This means that for most homeowners, the best way to carry out a soft wash with biocide is to call in a professional service to do it for you. A professional service will be able to operate the sprayer from the ground and carry out the soft clean safely and efficiently,
The bottom line is that you can clean your render with biocide and this is an effective method but there are some problems with doing it yourself. In addition, there is some risk of using chemicals in the local environment.
In our opinion the best way to clean your render is with steam cleaning. There is zero environmental damage and it is an effective way to remove stains on render.
If you have decided to repaint your render you will need to first remove the mould, so you should always carry out cleaning before you decide to go any further.
The good news is that it is likely that once you have cleaned your render, your walls will be transformed anyway but sadly there are no short cuts.
If you live in a bungalow or low level house, you may be able to scrub the mould off by hand using a bleach solution or biocide prior to painting but for many people the only way to effectively improve the appearance of render is to call in a professional service to clean it for you.