How to clean a blackened patio: 6 effective methods


Is your terrace made of stone slabs or is it simply tiled? Are you wondering how to clean it and especially how to bleach it? It is true that it is a chore to clean your patio. But after a wet winter or simply after a long period of rain, the dirt including moss and other algae sometimes settles. For appearance reasons, but also because this dirt makes your patio slippery, it is better to remove it quickly. This is also the fault of atmospheric pollution, which quickly darkens slabs and joints. So what are the effective methods for cleaning a blackened patio?

1 – Clean a blackened terrace with a brush

To clean and maintain a blackened terrace, it all depends on the type of coating. What material and what waterproofing of the surface? The degree of soiling of your patio also depends on its location. And then stains are more visible on light, smooth and even surfaces than on dark, colored or textured patio tiles. In addition, your terrace has no roof and is bordered by dense vegetation? In this case, it is normal that it is particularly exposed to humidity and therefore to darkness. Lichens, that is to say the associations of algae and certain fungi, can be very stubborn on patio tiles. Hot water and a stiff bristle brush will do the trick. Remove coarse dirt from the joints using a special brush or joint scraper. Take into account the hardness of the bristles to avoid scratching the tiles on your patio.

2 – Clean a blackened terrace with a Karcher

Using a pressure washer to clean the tiles on your patio is absolutely tempting and very practical. Pressure washers are also great for rugged decked decks if you know how to use them properly. Pressure washers circulate water from the outdoor connection and release it onto the ground with a pressure of up to a hundred bars – too much for most patio tiles, the surfaces of which can be roughened or even damaged by such power and get dirty even faster. Another problem is that if water gets into the gaskets at high pressure, it splashes onto the contents of the gaskets and is sure to hit a window or land on the front of the house. You can avoid this by working with your back to the wall of the house. Even sealed joints can be damaged with a pressure washer.

Therefore, you really need to use a Karcher with care. Put the sufficient distance or simply reduce the water pressure. With a high-quality device, this is easily done: at the push of a button. For tropical wood decks, try to equip yourself with some accessories that distribute the pressure over a larger area – these are usually two rotating spray heads. So your windows and facades fear nothing and stay dry and clean. If you connect this type of surface cleaner to adjustable pressure devices, you can even clean your “classic” wooden deck. In the case of high quality models, you can even apply a cleaning agent with the water spray by inserting the suction hose of the device into the cleaning agent container.

3 – Clean a blackened terrace with black soap

Here too you can use a stiff bristle brush. Your tiles themselves can be cleaned with a scrub brush, water, and mild or black soap. Water and neutral pH soap or black soaps are generally suitable for cleaning coatings or small stains. For hard natural stones like granite, gneiss or basalt, choose to clean them carefully using a pressure washer and brush, while soft natural stones like marble, limestone or stoneware can only be cleaned at low pressure. Stubborn stains on soft natural stone patio tiles must therefore be treated with special cleaners and rinsed with plenty of water after their action.

4 – Clean a blackened terrace with percarbonate of soda

There are also various recipes on the Internet for homemade cleaning products for patio tiles, for example based on soda, cornstarch or other home remedies. Try for yourself which solution works best for you. However, whatever your cleaning product is, test it first somewhere in an inconspicuous area to make sure your patio does not react badly to the product by fading for example. There are special products for cleaning patio slabs made of wood, natural stone or concrete. These must in any case be biodegradable and environmentally friendly, because rainwater carries residues into the soil of your garden.

5 – Clean a terrace blackened with sand

This method is particularly recommended if your patio is made of concrete. Sand, soapy water and a broom will work wonders. Many stains can be removed in this way. It acts like sandpaper and makes the blackness disappear from your floor.

6 – Clean a blackened terrace with bleach

This method can be considered, but really as a last resort. To avoid damaging patio tiles, you should adapt your cleaning products to the material of your patio and, if necessary, test them beforehand on an inconspicuous area. Chemical cleaners should only be used outdoors if they are specifically approved for this purpose. Weedkillers and even seemingly harmless household products like salt or vinegar should be avoided as they could enter groundwater directly.