What could be more stylish than a terrace or a garage entrance made of natural stone slabs? Above all, the irregularly shaped slabs made of porphyry, granite or limestone create a wonderfully natural ambience. When laying these polygonal plates, however, one or the other must be taken into account. With our tips, even inexperienced do-it-yourselfers can easily lay the irregularly shaped panels with a little skill.
The right material
Depending on where you want to lay the polygonal plates, you have to pay attention to the right material. In the outdoor area, the stone must absolutely be frost-resistant.
- Sandstone: relatively wear-resistant and frost-resistant, but is attacked by road salt
- Quartzite: frost and abrasion resistant
- Granite: resistant to frost and road salt, resistant to abrasion
- Limestone: less abrasion-resistant, sensitive to acids and salts (conditionally suitable for outdoor use)
- Porphyry: very resistant, ideally suited for garage entrances and terraces
- Marble: not frost-resistant, therefore not suitable for laying outdoors
Substructure
Before laying the polygonal slabs, a suitable substructure must be created. For larger areas such as terraces or garage entrances, polygonal slabs should not be laid in the gravel bed or gravel. A natural stone surface in the garden needs a weather-resistant foundation. If the area is to be driven on by a car, it must be particularly strong. There are various options for a substructure. Which variant you should choose depends primarily on the surface and the load to which you are exposing the surface:
- Layer of gravel and sand plus concrete slab (most stable solution)
- Mineral mixture or KFT (combined frost-proof base layer), grain size 0 - 32 mm
- Gravel or gravel bed (only for smaller areas and pure sidewalks)
For the foundation, the soil is excavated to the appropriate depth and then filled with a layer of gravel and sand or mineral concrete. The gravel bed must be compacted with a vibrating plate so that no cavities are created. A 15 centimeter thick concrete slab is then poured onto the gravel bed. After the concrete has dried thoroughly, you can start laying the slabs. Alternatively, mineral concrete (KFT) can also be filled in as a substructure. After compacting, the layer should be at least 20 centimeters high. An additional layer of concrete is not necessary in this case.
Tips for the substructure
1. To be on the safe side, the substructure and thus the excavation should reach down to the depth of frost. Information about the depth of frost in your
2. When laying polygonal slabs, it is important that the substructure has a slope of about 1.5 to 2% away from buildings so that the water does not flow to the house or garage will.
3. So that the substructure is stable, soil should always be removed. Excavation is also necessary if the path or terrace is set higher than the ground level.
4. In practice, a layer of KFT has proven itself well for terraces and sidewalks. The mineral mixture is easy to compact, very frost-resistant and has good load-bearing capacity. Even a shift of 20 is suitable for occasional driving. A 30 centimeter thick base layer is recommended for heavier loads.
5. You can create the most stable and permanent subsurface with a foundation made of a gravel bed plus a concrete slab.
6. It is advisable to coat a concrete slab with a primer before laying it. Once the primer has dried, a layer of liquid terrace waterproofing follows. Tape-shaped sealing makes sense where the terrace or the path adjoins the house or a wall.
Laying in a gravel or gravel bed
A lot of experience is required when laying polygonal slabs. The work should therefore preferably be carried out by a professional or an experienced do-it-yourselfer. In general, polygonal slabs can be laid in the gravel bed, but in most cases it is not advisable. Because there is a risk of the plates shifting and tilting. Nevertheless, this method has proven itself for laying garden paths.
- Excavate the soil to the depth of frost and fill it with fine gravel or chippings.
- If necessary, fill in the gaps with sand in order to achieve a better load-bearing capacity.
- Lightly compact the gravel bed with a vibrating machine for larger areas.
- Place the plates on top and tap into place with a rubber mallet. Make sure that the overall surface is even.
- Grout joints with grit or coarse sand.
Tip: It is important that only large and heavy slabs are laid as stepping stones that are at least three centimeters thick. With polygonal plates in the gravel bed there is a great risk that weeds will settle in the joints. Over time, the roots can lift the plates in some places, increasing the risk of tripping.
Laying on mineral concrete or concrete slab
In all other cases, the polygonal slabs must be laid with a frost-resistant substructure.
tool
- Folding rule
- Setting bar
- Spirit level
- Rubber mallet
- Joint iron
- Mortar bucket (or bucket)
- Trowel
- Comb spatula
- Watering cup with spout
- sponge
- Guideline
- Cartridge syringe for silicone cartridges
Personal protective equipment
- working gloves
- knee pad
- safety goggles
machinery
- Plate compactor
- Agitator (drills with agitators are too weak for the tough mortar)
- Angle grinder or diamond saw
material
- Polygonal plates in the appropriate amount
- Mineral concrete or mineral mixture grain size 0-32 mm (as a combined frost-proof base layer)
- alternatively: gravel, sand and concrete
- Bedding mortar
- Trass cement for grouting
- Cement film remover
- possibly boundary stones
- Natural stone silicone
Lay polygonal plates
Various work steps are necessary to lay the polygonal slabs. We will show you the steps in detail:
Step 1: prepare plates
It has proven to be useful to first distribute the irregular natural stone slabs dry on the substrate before the final laying in the mortar bed. In this way, you can set a successful pattern without time pressure and, in an emergency, completely reschedule it if something does not fit. Before applying the mortar, the substrate should be clean and slightly damp. Loose stones or dust prevent a good connection with the mortar. Therefore, sweep the concrete slab thoroughly in advance.
- First, sort the panels according to size and color.
- If you want the surface to end in a straight line, look for larger rectangular polygonal plates. These are perfect for the corners. All panels with long, straight edges are suitable for the side delimitation. If such plates are not available in sufficient numbers, you may have to bring individual stones into the correct shape with an angle grinder or a diamond saw.
- If necessary, stick a piece of masking tape on each of the stones and number them consecutively.
- With all of the larger panels in place, choose smaller pieces to fill in wider spaces. If necessary, remaining panels must be smashed for this purpose.
- Clean the panels with a sponge and clean water. Dirt and dust on the back of the natural stones prevent the mortar from adhering.
- In the case of polygonal plates made of basalt, the back should also be roughened with a claw board and cleaned under running water. A contact slurry as an adhesive bridge facilitates the laying.
Step 2: lay curbs
If the terrace or path is to have a straight end, the curbs are laid first. These are placed in a foundation made of lean concrete and tapped in with a rubber mallet to the appropriate depth. To do this, stretch a straight line over the entire length of the edge to ensure that the stones are in a straight line as well as at the same height.
- If you have planned additional edging from other stones, both these and the first row of straight-edged polygonal slabs laid in the lean concrete bed so that they do not stick together move.
- Start by laying the curbs on the house wall or another boundary so that there are no gaps that are too wide later.
Step 3: insert natural stone plates
Now move the remaining stones away from the end. To do this, apply a layer of bedding mortar about 5 centimeters thick to the mineral concrete or the concrete slab and straighten the mortar with a wooden board or a leveling batten. Carefully press the pre-sorted stones into the earth-moist mortar bed. Make sure to pay attention to the height and the joint width. The joint width typical for polygonal slabs is around 3 to 5 centimeters. Then the stones are tapped with a rubber mallet. You should constantly use a spirit level on a level surface and also on the necessary slope from the
Tips
1. If the substructure consists of a concrete slab, this should be moistened before the mortar is applied so that the mortar adheres better. The installation is done wet in wet (not wet). This means that both the subsurface and the polygonal slabs should be slightly damp when laying.
2. Only as much mortar is applied as is needed to lay around two to three panels.
3. Only mix small amounts of mortar fresh. Since this is applied very thickly (thick bed process), it hardens very quickly. Any residues that have already dried in the cement tub should no longer be used. For beginners, it is advisable to mix half a sack at a time.
4. If the panels are of different thickness, always start by laying the thinner panels to ensure an even surface.
5. When tapping in larger panels with a rubber mallet, it is best to use a protective board so that there are no cracks or gaps in the natural stone.
6. When the natural stone slabs are pressed in and pounded in, the spaces between them fill up more or less with laying mortar, depending on the thickness of the natural stone and the pressure you exert. This should be removed promptly with a joint iron.
7. Protect the newly laid area from rain if this should be necessary. A large foil is suitable for this, which is weighted down with stones or wooden slats to prevent it from flying off.
8. Do not step on the freshly laid polygonal plates until the mortar has hardened well. Otherwise the panels will shift and you will get an irregular surface.
Grouting polygonal plates
To grout the natural stone slabs, you need trass cement, which is either poured into the joints with a trowel or poured liquid into the gaps. Grouting may only be carried out when the mortar has completely hardened. You are on the safe side if you wait a day after laying before you start grouting.
- Make sure not to contaminate the panels unnecessarily when pouring the joints, as cleaning later can be problematic or even impossible. If something goes wrong with the grout, it should be wiped off immediately with a damp cloth or sponge.
- The consistency of the grout for paving joints must be liquid so that it can be easily poured into the joints. In order for it to harden well, however, it must by no means be too watery.
- Before the actual grouting, the gaps and the stones must be moistened with water. A quast (wallpapering brush) or a sponge are suitable for this.
- The liquid trass cement is particularly easy to fill in with the help of a beaker with a handle and a spout.
- Also use a step-by-step approach to grouting. After pouring the grout to a level slightly below the polygonal plates, the grout is washed off and smoothed with a damp sponge. Be sure to wash off residues from the panels with a clean sponge.
- The side of the house or a wall connection is not filled with grout. At the very end, after the joint compound has hardened, an expansion joint is made between the other stones with natural stone silicone.
Theses
After the grout has hardened, the entire installation surface is washed off thoroughly with water. In order to move the gray veil on the body, cement veil remover is necessary. Follow the instructions on the packaging and, if necessary, wear appropriate protective clothing.
Tip: The cement veil remover must match the laid natural stone, otherwise its surface could be attacked. Limestone and the joints, for example, do not tolerate acidic agents.
sealing
In order to protect the new natural stone terrace permanently against the weather and moss growth, a seal can be applied after cleaning and drying.