With a little skill, the right materials and craftsmanship, you can build a terrace in the garden yourself. The substructure, the foundation, is always important. Here are some tips for constructing a terrace.

Solid substructure necessary

Regardless of whether paving stones or slabs are used for a terrace construction, a solid foundation is always necessary. Without the appropriate substructure, the stones would sink down over time. Therefore, detailed planning is important. But that alone is not enough, the substructure must also be installed professionally in order to be able to enjoy the terrace for a long time. The subsoil consists of several layers such as

  • Planum
  • Frost protection and base layer
  • leveling or bedding layer

The material used for this becomes finer and finer towards the top. The terrace construction takes place in different steps. More on that below.

Note: All layers that are applied over the naturally grown soil are referred to as the substructure. These must be safe and pressure-resistant and also allow soil water to drain well into the subsoil in order to prevent waterlogging.

stake out area

First of all, of course, the size of the area must be precisely defined for the terrace construction. It should be noted that there is also enough space for an edging. This is necessary so that later the individual layers of the foundation and, of course, the terrace covering above them cannot shift sideways. Therefore, about 20 centimeters of working space should be added. The following materials are required for staking

  • short wooden or metal stakes
  • a hammer
  • a guideline
  • level
  • Richtbrett

Four pegs are usually required for a rectangular terrace structure. It is important when staking out that there is a slope from the house to the garden. This should be at least two percent, although a gradient of three percent is usual for irregular or natural paved surfaces. The area is now staked out as follows:

  • Drive pegs into the ground with a hammer
  • Use a spirit level to install the slope
  • place them on the straightening board
  • set incline
  • then stretch the cord accordingly, connect with pegs
  • The height of the guideline corresponds to the height of the paving surface
Note: With a two percent gradient, the area drops by 2 percent over a meter length. In other words, the height difference per meter is two centimeters.

excavate soil

The excavation depth depends on the height of the foundation, the type of soil and the terrace covering used. When constructing a terrace, an excavation depth of between 15 and 30 centimeters is usually calculated, depending on the risk of frost. A spade is used to excavate the area. Depending on the nature of the ground, a pickaxe may also be necessary. The unsustainable soil such as topsoil or clay is then removed until the desired depth is finally reached. The incline must also be taken into account when digging.

The floor must then be carefully leveled. Roots and stones should no longer be present. Finally, it is compacted with a vibrating plate. The water must then be able to run off well. The resulting floor area is also referred to as planum.

Tip: Heaped up soil or clay soil is not particularly suitable as a base for fastening. Filling sand and cement should be mixed in here.

set curbs

Edge stones are set so that the terrace structure remains stable and does not slip sideways. can be used

  • Lawn edging stones made of concrete and natural stone
  • cobblestones
  • palisades or
  • L stones

The stones are placed in an earth-moist concrete bed. It is best to use dry concrete mixed in a mortar bucket for this purpose. Procedure is as follows

  • Set stones in concrete bed
  • that should be 5 cm high
  • align along the guideline
  • Align the stones with a rubber mallet and knock down
  • check the slope with a spirit level
  • form a wedge-shaped concrete support to stabilize it
  • Support from both sides of the stones
  • should be at least one third of the stone height
  • Allow concrete to harden

Base and frost protection layer

After the concrete for the curbs has hardened and the subsoil is well compacted, gravel or crushed stone can be introduced. By introducing this layer, the water is drained off, the terrace becomes frost-proof and finally it is prevented from sagging. At the same time, the soil can be aerated. Here, too, the gradient must be observed for each layer.

The material should be introduced in several layers:

  • each layer height about 5 to 10 cm
  • Bring in the material when it is earth-moist
  • compact each individual layer well with a vibrating plate
  • all layers must retain drainability
  • Foundation should be compacted at least three times

The final height of the crushed stone or gravel layer can be easily calculated by subtracting four centimeters of chippings and the thickness of the terrace covering from the excavation depth. In order to keep the height correct, a marking can be made on the curbs.

It doesn’t really matter whether you choose gravel or crushed stone. Both are possible, although gravel is used particularly frequently in areas that are subject to heavy loads. The grain of the respective material is important

  • with gravel grain size 0 to 32
  • for gravel 0 to 45
Note: It should be noted that if you compress three times, there is a volume loss of around 3 percent.

bedding or leveling layer

As a rule, terrace slabs are laid in a bedding layer made of a mixture of chippings and crushed sand. This comes at the end on the frost protection and base layer. The mix of grit and sand ensures good drainage. Depending on the terrace covering, the bedding layer should be four to five centimeters high. It is then important that the grit bed is leveled using a straightedge. In order to be able to smooth off the chippings without any problems, two long metal pipes are placed parallel to each other on the base course as an aid.

The following work steps are necessary for this

  • Lay pipes or other metal profiles on the surface
  • The distance between these must correspond to the length of the straightedge
  • Pad the pipes with some grit
  • adjust to correct height
  • stretch a guideline over curbs
  • always pay attention to inclines
  • measure from strings
  • Align the pipes accordingly
  • Fill in gaps with grit mixture
  • Use a straightedge to scrape off the grit above the pipes
  • make saw-like movements
  • then carefully remove the pipes
  • fill any voids with grit
  • no longer enter the area
  • if necessary, lay boards as a walkway

The grain of the bedding material should be fine:

  • Split 0/2, 1/3 or 2/5
  • Sand 0/2 or 0/4

After this work is done, nothing stands in the way of laying the terrace slabs.

frequently asked Questions

Both are mixtures of stones with a size between 2 and 63 mm. The only difference is the shape of the individual structures. Gravel consists of round stones, better known as pebbles. Chips, on the other hand, are quarry stones with sharp edges.

Yes, there is a possibility. However, the surface must then be flat and undamaged. The concrete surface should then be connected to the house wall. It is necessary to use drainage mats to drain water away. These then divert the water laterally.

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