Cleaning terrace slabs – remove moss and algae from the terrace

Mechanical aids

• Grout brush / grout scraper
• Flame retardant device
• Steam device
• high pressure cleaner
• Infrarotbrenner
• Hot water foam device

Home remedies

• Mixture of soda, cornstarch and potassium permanganate
• Coke
• Soft soap and ingredients
• Hydrogen peroxide
• Commercial vinegar cleaner
• Vinegar and salt are prohibited by law
• Preventive measures

Mechanical aids on stone terrace slabs

One of the most common building materials for terraces is stone in any form. From simple exposed aggregate concrete to high-quality natural stone, creative do-it-yourselfers lay the most diverse variants. Moss and algae care less about the quality, because they thrive here particularly abundantly, whereby they seem to cling to the joints. Anyone who consciously decides against the use of a chemical club will find effective support in the following devices and tools.

Grout brush / grout scraper
Without a certain amount of force, this method of moss removal does not work. It compensates for this fact with a completely environmentally friendly mode of operation with very little financial outlay. A joint scraper cleans even the smallest gaps with its curved steel blade. The joint brush with its hard bristles made of metal or plastic is no less efficient. Larger areas that are greened with moss and algae can be treated more quickly with broad brushes.

Steam
device Heat of all kinds removes moss and algae from terrace slabs that are made of stone. The effectiveness is based on the thermal effect, which causes the protein cells to burst. The heat shock is also generated by a steam device. In contrast to a jet of hot water, which could wash out the grout, the boiling steam specifically destroys moss and algae mats. Miserable leftovers are simply turned away. The precautionary measure of an attempt in an inconspicuous place is also recommended here.

High-
pressure cleaner In principle, the high-pressure cleaner works in the same way as the steam device. The cleaning effect on the stone slabs is disproportionately higher than when using steam. Not only moss and algae have to give way, but all deposits that have accumulated. The disadvantage is that grout is washed out. Experienced hobby gardeners use special dansand or polymer sand for new grouting. These types of sand have a decidedly inhibiting effect on all weeds; thus also on moss and algae on terrace slabs.

Flaming device
Here, a jet of fire with a temperature of up to 2,000 degrees shoots out of the gas-powered device. In a matter of seconds, moss and algae are destroyed. A few hours after the treatment, the unwanted coating comes off easily and can be swept up. Since not every stone quality can withstand this rigorous cleaning method, a prior test on an inconspicuous area is advisable. The device should not be used along the transition to the lawn or bed because it radiates heat up to that point.

Infrared
burner Instead of using fire, as with a flame burner, the infrared burner works against moss and algae with heat radiation from a glowing grid. While root and seed weeds are only scorched in this case to reappear after a short time, moss and algae are no longer visible for the rest of the season. In this case, however, you cannot avoid a thorough follow-up either.

Hot water foam device for large terraces
An innovation in the ecological removal of moss and algae is becoming more and more popular. It combines hot water and a natural foam made from 100 percent plant sugar based on coconuts and corn. Spread out on the terrace slabs, the mix keeps the heat there for a whopping 2 minutes. This time is sufficient to completely destroy the cell structures. After a further 5 minutes the foam has dissolved. Now it takes another 2 to 3 days for the green covering to turn brown before you can sweep it with a broom. The use of pesticides is therefore unnecessary. The smallest device to date is only profitable from a terrace area of ​​200 square meters. It will be interesting to see whether suppliers will soon be found who will offer suitable hot water foam devices for private use.

Thermal devices unsuitable for wooden terraces

Although moss and algae find first-class growth conditions on wooden terrace slabs, you should refrain from rashly reaching for a high-pressure cleaner, steam device or even a flame cleaner. The wood pores would be seriously damaged by the heat. The grain becomes cracked. Splinters form that make walking barefoot almost impossible.

If you aim to remove moss and algae from a wooden terrace, you have a whole arsenal of tried and tested home remedies and environmentally friendly methods at your disposal. The procedures outlined below eliminate the green patina of stone and wood alike.

Home remedies for moss on patio slabs

Moss and algae thrive wherever nature offers them suitable growth conditions. They take no account of the building plans and wishes of the people. The more humid the location, the more intensely the green plaque spreads on the terrace slabs. Anyone who cannot or cannot use mechanical aids for removal can use one or more of the following home remedies.

Soda and cornstarch
You probably already have the ingredients for an environmentally friendly and at the same time powerful moss and algae remover at home. Washing soda, i.e. sodium carbonate, and cornstarch are required. This is how you can easily make the home remedy yourself:

• Mix 3-4 tablespoons of Mondamin or Gustin in lukewarm water
• Warm up 5 liters of water in a saucepan
• Add 100 grams of soda

Finally, stir in the dissolved cornstarch until it becomes a paste with the consistency of wallpaper paste. The still warm mass is applied thickly to the terrace slabs with a brush. Leave the mixture on for 4 to 5 hours. Now scrub your terrace clean and rinse thoroughly.
If it is stone patio slabs from which you want to remove moss and algae, the efficiency of the home remedy can be increased. Add a dash of potassium permanganate from the pharmacy to the mixture. Before doing this, dilute 15 grams of the powder in 10 liters of water. When using it, make sure that you wear gloves, protective goggles and non-sensitive clothing, as potassium permanganate strongly oxidizes. The strong coloring home remedy should not be used on light natural stone without a prior test run.

Cola
The phosphoric acid in the popular soft drink is said not to be good for moss at all. At the same time, there is no need to fear discoloration, nor is the joint material between the terrace slabs attacked. Results can only be expected in undiluted application. In the absence of credible aptitude tests, at least trying it on yourself cannot do any harm. It should be noted, however, that the high sugar content could attract flocks of ants and other insects.

Means based on soft soap
Environmentally conscious hobby gardeners are familiar with soft soap in some respects. This biologically harmless substance is often a component of agents used to control pests and plant diseases. Curd soap is also ideal for removing moss and algae from patio slabs. If you add a few other ingredients, a natural care product is created that you can produce yourself without much effort and at low cost:
Ingredients for 10 liters of cleaning agent :

• 100 ml liquid soft soap
• 10 liters of sparkling hot water
• 60 g washing soda
• 60 ml Glycerin
• 120 g stain remover

All ingredients are mixed in a sufficiently large container. Even if you are insensitive to the various ingredients in the solution, you should not be without rubber gloves. The synergy effects cause the effectiveness to be increased, in some cases considerably, so that undesirable skin irritation could quickly occur. Apply the product to the moss-covered terrace slabs immediately after production. The cleaning-active oxygen that is formed is only available for a very limited period of time. Ideally, you should apply the cleaning agent with a sponge and let it work for about 20 minutes. Then scrub the surface and rinse thoroughly with clear water. If used correctly, you should have a clean terrace in front of your eyes for six months.

Hydrogen peroxide
The oxidizing agent offers a wide range of possible uses. This also includes removing moss and algae from patio slabs. Applied neat on the green patina, the agent immediately attacks the tiny fungi of the algae and moss plants. They dry up quickly and die to be turned away.

Leave the vinegar, salt and lemon juice aside

It’s an old-time relic and it still holds up stubbornly. We are talking about the so-called home remedy vinegar and salt as an effective control agent against weeds, moss and algae. The fact is that the active ingredient combination has been prohibited by law since 2012, especially on sealed surfaces. There is good reason for the offense to be punished with a fine of up to 50,000 euros, because the consequences for the environment and health are incalculable. The hot mixture seeps into the groundwater and in this way kills all microorganisms in the soil. In the long run, nature would come into a life-threatening imbalance for humans and animals.

In addition, the resulting acid causes considerable damage to terrace slabs, which by far outweighs the cleaning effect. Stone slabs in particular then have brown acid stains that can no longer be removed. In addition, the grout dissolves with further, unpleasant consequences.

However, there is nothing wrong with using a standard vinegar cleaner to clean terrace slabs at an early stage of the moss infestation.

Preventive measures

Probably the most economical way of combating moss and algae on a terrace is based on effective prophylaxis. This begins with the selection of the material from which the panels are made. The smoother the surface, the less the tiny plants can gain a foothold. The laying technique also plays an important role. Where moisture can accumulate, moss and algae are not far.

• Patio slabs prefer made of granite, marble or ceramic
• Naturally glaze wooden panels with beeswax or linseed oil right from the start
• Always lay the surface with a slight slope so that no waterlogging occurs
• Use Dansand or polymer sand for grouting stone slabs

If you prefer a wooden terrace, we recommend using panels made of WPC. The abbreviation stands for wood-plastic composites, i.e. a wood-plastic combination. A multitude of beneficial attributes speak for this innovation, which has made a lot of talk among specialists and do-it-yourselfers alike. The surface dries particularly quickly and leaves algae or moss no chance. Without the use of wood preservatives or special oils, lukewarm water is sufficient for cleaning.

Conclusion
In order to completely remove moss from terrace slabs, there is no need to use environmentally harmful chemical-based preparations. Scientists as well as committed hobby gardeners have vehemently compiled an extensive collection of efficient methods for removing moss and algae from a terrace. The spectrum ranges from mechanical aids and effective home remedies to effective prophylaxis. If that’s not enough, new insights are constantly being added, so that it is worthwhile for interested homeowners to regularly update themselves.