In most cases, paving slabs are laid wet, i.e. in a bed of concrete or mortar. In the case of terraces and other outdoor applications, however, this can be disadvantageous and is usually not necessary at all in terms of effort. Here you can find out how to lay natural stone slabs, such as polygonal slabs or slate slabs, while doing without the expensive and time-consuming cement-based building materials.
The alternative to concrete
Laying quarry stone slabs without mortar - is that even possible? Yes it works! Ultimately, the concrete only serves to hold the slabs in place. Easier, cheaper, and in many cases even more permanent, can be achieved at least as well by placing the natural stone slabs in a bed of gravel. If the edge of the laid area is fixed in its position, the panels secure each other against unintentional shifting. And not only with polygonal plates, but also with rectangular or square plates. How the work will be implemented can be easily understood using the following steps.
NOTE: In general, the instructions can also be used to lay slate sheets without any problems. Overall, however, you should then work particularly carefully, as slate has a much stronger tendency to to break under tension, to splinter or "slate up", that is, to separate itself into its individual layers split up.
Substructure
While laying in mortar usually takes place on solid concrete floor slabs, laying in gravel does not require this solid, but also expensive substructure. Instead, it is sufficient to strengthen the subsoil so that it is able to bear the load Exposure to water and frost does not move and last of course is level enough to allow the laying to take place enable.
The steps mentioned here are only necessary if a stable substructure is not already in place as a result of a new building measure or something similar.
Required materials and resources
- Mini excavator, alternatively spade, pickaxe and shovel
- Buckets, wheelbarrows etc.
- Spirit level
- Straight, straight lath or other straight lath with approx. 2m length
- Plate vibrator
proceed
- Dig the existing underground 80cm deep
- Properly dispose of excavated material, e. B. to excavated landfill, alternatively disposal via landscapers, earthworks companies or the like
- Excavation on all sides approx. Create 40 centimeters beyond the edge of the pavement
- Put in frost-proof, i.e. water-draining and at the same time load-bearing substructure, material e.g. B. KFT ("combined frost protection and base layer"), or mineral concrete
- Installed material after approx. Compress the 30 centimeter layer with a plate vibrator, then apply further layers up to the target height
- Define the upper edge of the substructure as follows: planned surface of the quarry stone slabs minus the slab thickness, minus five centimeters for the bed of the natural stone slabs
NOTE: Mineral concrete is mentioned as a possible substructure. Despite the name, it is not a classic, cement-bound concrete. Instead, mineral concrete is a mixture of different gravel grain sizes which, thanks to its composition, can be compacted very well and thus designed to be load-bearing.
Preparation for laying
Once the substructure has been created, frost, rising soil moisture and, at the same time, collecting rainwater can no longer harm the subsequent covering made of natural stone slabs. Now it is important to create the right conditions for the later laying of the panels. These prerequisites include securing the edge of the covering against displacement, as well as the production an exact subgrade on which the slabs are then in one level and without thresholds or tripping points lie.
Required materials and resources
- bucket
- hammer
- Rake / straight edge
- Spirit level
- Guideline
- Carpenter nails or other pegs
- Possibly trowel
- Tape measure / yardstick
The edge protection
There are various options for securing the edge of the terrace against movements which then affect the entire area:
The edge angle
A perimeter trim can be used completely without mortar. Usually made of plastic, it is an angle profile, the upstanding leg of which serves as a stop for the plates. The horizontal leg enables the attachment to the subsurface via a perforation using long carpenter nails or special pegs:
- Measure the exact position of the terrace edge
- Lay out the angle profiles and align them according to the measurement result
- Aids: Stretch the guide cord over two pegs for straight lines
- Carefully hammer in the securing elements and check the position of the profiles
The mortar wedge
If you don't want to choose a mortar bed for the plate surface, but can still use this material for details, you can alternatively help yourself with a mortar edge. Although this is only created after the tiles have been laid, this variant is already explained here for a better overview:
- Mix suitable mortar for outdoor work according to the manufacturer's instructions
- Check the outermost row of panels again for exact positioning
- Apply the mortar on a frost-proof sub-structure next to the edge slabs and spread it in a wedge shape towards the slab
- Ideally, keep the top edge of the wedge just below the top edge of the plate
Curbs
The setting of kerbstones requires a particularly high level of effort. In addition to creating a very good hold, they also enable an optical edge delimitation of the area equipped with polygonal plates. Border stones of a small height are sufficient, as they only have to absorb slight lateral pressure if the work is carried out correctly:
- Stretch a guide line over pegs, taking into account the alignment of the terrace edge and the desired upper edge of the borders and paving
- Prepare suitable outdoor mortar according to the manufacturer's instructions
- Apply lumps of mortar in the area of the board ends on a frost-proof substructure
- Place border stones loosely on lumps of mortar, align and press down lightly
- Align the borders with a rubber mallet and lightly hammer them into the mortar bed until the desired position is reached
NOTE: According to the information on edge protection, one might well ask oneself whether these methods are visually appealing from the outside. It should be noted at this point that the overhang of the frost-proof substructure can be refilled with soil after the work has been completed. After renewed greening, the overhang of the substructure is just as invisible as the securing of the terrace edge.
The planum
I.
Once the edge of the terrace area has been secured, the final level is created on which the slabs are then placed. A fine split, so-called noble split, is used for this. If the surface is created without imperfections and hills, all common ones can be applied to it Lay sheet materials up to slate, without later bumps or tripping hazards to fear.
NOTE: One reads again and again that terraces should be inclined by around two to three percent for proper drainage. If this is desired, the guide line in the following description must be inclined in the direction of the desired slope. When laying in a bed of gravel, rainwater can seep away through tile joints, so that especially with polygonal slabs and other slabs with large joint widths, the inclination is less important is. Even smaller terraces can be aligned quite well without a slope, since less water can collect overall.
Required materials and resources
- Right
- Spirit level
- Rake
- bucket
- shovel
- Guide line with pegs
proceed
- Apply high-grade split, grain size up to a maximum of 3-5 millimeters, to the substructure between the edges and distribute roughly
- Set up the exact target height with a guide line on the edge of the plate
TIP: Set up the guide line in such a way that the line indicates the upper edge of the guide line when the split surface has reached the target height
- Set up a spirit level on a straight edge and align it in the area of the terrace edge according to the height of the guide line
- Pull off the split with a straight edge horizontally or following the created slope of the cord
- Remove excess split, add in the case of imperfections and peel off the area again
- Pull straight logs crosswise from the terrace sides to eliminate waves when working in one direction
The relocation
Now the last thing to do is to insert the desired slabs on the created subgrade and between the existing edge boundaries. For the sake of simplicity, we assume that panels can be inserted without breaking or sawing cuts.
Required materials and resources
- Right
- Spirit level
- Guide line with pegs
- Rubber mallet
proceed
- Carefully place the selected panels in the split bed from one side of the terrace and press them down gently
- In the case of slight unevenness in the split, carefully tap the panels horizontally with a rubber mallet
- Regularly check the position above the straight edge and level using the straight line
- Desired joint width between panels using a suitable spacer, e.g. B. Ensure wooden strip or specific plastic molding, remove temporary spacers later
- In the edge area of the surface that does not run out into full slabs, cut stones using a cut-off machine and a suitable stone disc, do not forget to bevel the edges
- After laying all quarry stone slabs, fill the joints with suitable joint sand and put sand on the Give the terrace area and sweep it in all directions with a broom, process after a few days due to subsidence of the Repeat sands
TIP: When laying slate panels, preparing the edge panels with a sharp hammer can be easier than with technical aids! However, you should first familiarize yourself with the technology on a leftover piece! Special spacers can be used to create equivalent joints, which are only used in apply to the lower half of the board thickness and thus not appear after the joints have been filled step. They remain permanently in the joints and stabilize the surface, especially during construction and until the joints are completed, to prevent the panels from shifting against each other.
Why joints at all?
Unsuspecting readers may now ask themselves why the stone slabs are laid with joints at all. But if they were tightly butted, they would have been much more secure and at the same time more harmonious in the look of the stone surface.
The joints between the panels serve several functions:
- Drainage option for rainwater
- Decoupling of the plates from one another, otherwise with (tilting) movement of one plate also movement of neighboring plates
- Compensation option for dimensional tolerances between the panels
In addition, joints are also able to hide one or the other inaccuracy in the execution. We assume that every do-it-yourselfer will do a conscientious and precise job, but even professionals are not immune to mistakes and like to use the advantages of tile joints for themselves.
