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If the terrace is to be redesigned, then the question arises as to the substrate for the terrace slabs. Chips, sand or even fine gravel can be used here. The different variants are explained below.

In a nutshell

  • Grit as a substrate is one of the variants that is chosen most often by default
  • Grit or gravel is always chosen as the bottom layer as frost protection before sand or gravel is distributed on top
  • Gravel is also possible as the first frost protection layer directly above the ground, but should have a certain thickness
  • On top of the frost protection layer, sand, gravel or chippings of a smaller thickness can be used as an inlay layer for the stone slabs
  • The bottom layer of gravel must be leveled with a vibrating plate, otherwise the stone slabs will sink later

grit as a substrate

Anyone who chooses a gravel bed as the substrate for their terrace slabs chooses the standard. Because this is the most common way to lay the slabs straight and non-slip on a terrace. The prerequisite for this is the following procedure:

  • Mark out the terrace area and dig out the earth
  • about 30 cm to 50 cm deep overall
  • Excavation is calculated depending on the height of the terrace slab
  • Fill in the first coarse-grained layer of grit
  • about 10 to 20 centimeters high
  • Compact layer by layer with a vibrating plate
  • Fill in finer grit about five centimeters over this
  • peel off plan
  • Lay terrace slabs in the gravel bed
  • Leave gaps of three to five millimeters

The stone slabs should be placed in the gravel bed in such a way that they are flush with the surrounding height. It is therefore important to measure the height of the slab before excavating so that you can calculate exactly how far to excavate. The stone slabs are evenly aligned with a rubber mallet and a wooden board as well as a spirit level.

Tip: If you choose stone slabs for outdoor use, you should make sure that the surface is not too smooth. Because when it is wet, the risk of slipping is particularly high in such a case.

use sand

If sand is to be used to create the stone slabs as a terrace or walkway, then an additional layer of gravel or grit is required as a frost protection layer. So the sand is applied to the vibrated and solid layer and the slabs are laid in it. Since sand attaches well, the plates are very firmly embedded in it when they are fixed again with a rubber mallet after laying them down.

Notice: With any type of laying terrace tiles, you must not do without a frost protection layer. This is a prerequisite for the terrace slabs not lifting up later when there is frost and the surface then becoming uneven. If no concrete base is available, then you must always lay a first layer of coarse crushed stone or chippings before the actual bed of chippings, sand or gravel is filled.

underlay gravel

Gravel can also be used to create a surface made of stone slabs, this is a different variant of using grit. Because gravel is also available in different grain sizes. Here's how to do it:

  • use coarse-grained gravel as a frost protection layer instead of grit
  • also fill and shake
  • add another layer of finer gravel
  • place the plate on top of this

Notice: It is always important that you compact the bottom layer of crushed stone well with a vibrating plate. Otherwise, the terrace slabs will sink later, which should be avoided. Then various slabs sink sideways, the terrace becomes uneven. You can rent a vibrating plate by the day from a well-stocked specialist shop or a hardware store.

Quartz sand for the joints

When the terrace slabs are all in place, fine quartz sand is scattered over the surface and the joints are wiped well with a broom until they are filled to the top. This work can be done over and over again over a period of several days, as the quartz sand settles a little after a while and the process should therefore be repeated.

Tip: This use of quartz sand is not absolutely necessary. If you have laid your stone slabs on grit or gravel, for example, and left extra large joints here so that the subsurface shows through, then of course you do not use sand as a joint filler.

Which variant do you recommend?

If you don't want to work with concrete, all three methods are equally suitable. The question here is rather how the surface should look later. There are natural stones or stone slabs that are laid close together and between which only small joints can be seen. On the other hand, there are also areas where the gravel should shine through between the stone slabs. The various procedures are to be used as follows:

  • Always use gravel and grit as a frost protection mat
  • here you can choose the cheaper variant
  • Gravel is mostly round
  • Split is usually rather angular
  • choose what you like better between the joints
  • pay attention to the color of the stone slabs
  • Different colors available for gravel and grit
  • Use sand only when joints are almost closed

frequently asked Questions

Can I lay the patio tiles myself?

Laying terrace slabs yourself is quite easy. Even as a beginner, you don't need a professional for this. The slabs can be easily laid on sand, grit or gravel. So you can assume that as a beginner you will be able to cover one square meter in about 90 minutes. You can plan two to three days for a larger area yourself and save yourself the costs for a specialist.

I excavated the ground too deep for the terrace, what should I do?

If you have miscalculated and removed too much soil from the patio bed, you can also apply another sub-layer of gravel. This must be compacted again with a vibrating plate. You can also fill in the excess soil that you have removed. Keep in mind, however, that you must also secure this layer of soil with the vibrating plate, otherwise the subsoil will become too unstable due to the loosened soil.

How do I get even joints?

There is a simple trick to ensure that the joints are straight and evenly wide. With concrete slabs, you can use joint crosses, which are also used when laying tiles. Otherwise, set up small pegs at regular, measured intervals at the edge of the terrace, to which you stretch a cord. You then lay the panels along this path and thus obtain the desired width of the joints.

How do I know how much material I need?

If you yourself do not know how to calculate the amount of material, then the specialist will help you with this when ordering. All you have to do is provide the key data, which includes the size of the terrace, the desired height of the gravel layer and the desired height of the second layer of gravel, grit or sand and the thickness of the terrace slabs, and you will receive exactly the right amount of building materials.

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