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Normally, the floor of a patio is exposed to all kinds of precipitation. It is therefore important that the water can run off and the terrace covering can dry quickly. This requires a slight slope across the entire terrace.

In a nutshell

  • slight slope of terrace and ground necessary for water drainage
  • Necessary inclination depending on the material of the terrace covering
  • Depending on the material, the terrace slope should be at least 2 to 3 percent
  • our recommendation: calculate the value on paper beforehand and then implement it when building the terrace

Recommended slope

The degree of inclination depends on the material of the terrace covering. A gradient of 2 to 2.5 percent is necessary for a terrace surface with fine stoneware, natural stone slabs and also concrete paving so that the water can drain off well. Laid natural stone paving has a rougher surface and should therefore have a gradient of 3 percent.

Tip: If you are building a terrace floor with a substructure, you can also provide the planks with a slight incline.

gradient calculation

First of all, it is advisable to calculate the necessary value of the slope on paper, because it will tell you how to stretch the guideline on the surface of your terrace.
The terrace slope indicates the degree of inclination of the terrace surface. In order to be able to calculate the value correctly, the difference in height and the length in the direction of the slope are necessary.

The general formula is as follows:

Percent gradient = (height difference in centimeters / length of the route in centimeters) *100 percent

Calculation of the height difference:

(gradient in percent / 100 percent) * length of the route in centimeters = height difference in centimeters
Example with a terrace slope of 2 percent and a terrace length of 600 centimetres:
Height difference = (2 percent / 100 percent) * 600 centimeters = 0.02 * 600 centimeters = 12 centimeters

slope alignment

The degree of inclination should be such that the water can easily drain off the terrace floor. Optimally, it should run away from the house, even if the house terrace is built around a corner. With wooden floorboards, the slope is aligned along the floorboards. Especially when the surface of the decking has a corrugation. With a jointed terrace covering, the precipitation runs off along the joints.

Tip: The slope leading away from the building wall always creates a water drainage edge. Under her, however, must there is a drainable soil. However, you can alternatively bring in a downspout so that the precipitation can run off better.

Steps to create a gradient

Depending on the type of terrace, a slope must be built in at different planning stages. For example, a gravelled floor under a metal or wooden deck should be given an appropriate slope.
The following instructions for the example with a height difference of 12 centimeters show you how to create the necessary incline on this floor. However, the excavation is already finished, the ground has been consolidated and a layer of frost protection has already been applied.

Prepare and lay out material and tools

You will need the following materials and tools:

  • 4 wooden pegs or twine nails
  • gravel
  • hammer
  • cords
  • pencil or marking chalk
  • Tape measure or folding rule
  • wall angle
  • level
  • Squeegee or squeegee
  • 2 pull gauges

Drive in wooden stakes or twine nails

The terrace is highest on the building to which the terrace area adjoins. Drive in the first post or string nail here at one corner of the patio area, while driving the second post at the opposite corner of the decking area on the house wall. Now hammer in the other two posts at the corners at the other end of the patio area, parallel to the wall of the house. A masonry angle helps to establish the right angle of their connecting lines to each other.

Mark the height of the first stake and attach the cord

Now mark the height of the terrace construction at the highest point on the first post on the house wall and attach a guide line at this height.

Transfer height to second stake and attach string

Now transfer the height from the first peg to the second peg on the house wall by stretching the cord between the two pegs and using a spirit level. The guideline must be exactly balanced. Then attach the cord to the stake and mark its location.

Mark the height with the calculated slope on a peg at the end of the terrace

Stretch the plumb line horizontally around the opposite post at the other end of the deck using the spirit level and draw a mark. From this mark, measure 12 centimeters downwards, mark the difference in height there and stretch the cord tightly around this point.

Transfer height with calculated slope to second peg at deck end

Now transfer the height from the first peg to the second by stretching the string between the two and again using a spirit level to ensure the string is level. Mark the location of the cord.

Fasten the guide line tightly to the pegs

Lead the cord back to the first post on the house wall. Now pull the guide line really tight at the markings on the pegs or cord nails so that it cannot shift.

Tip: It is best to have two people attach the cord and pull it tight.

Subtract slope

Now run screed gauges along the strings that will indicate the final deck pitch. Align them evenly, fill in the space between them with gravel and level off the slope with a screed board or screed. For large areas, work piece by piece.

frequently asked Questions

Can I also add a slope to the terrace afterwards?

Yes, that is possible, for example with a sloping screed. It can also be retrofitted if you have a straight floor that should have the necessary incline. The inclination can be achieved, for example, with a so-called leveling mortar.

Is there a way to build my wooden deck without a slope angle?

Yes, there is a way, for example with Naturinform's zero-degree solid planks. They have a special shape and a water-repellent surface, so the water can run off automatically. With this floorboard system, a slope is no longer necessary.

I want to build two terraces of different sizes. Do I have to buy two squeegees?

Not necessarily, since there are also pull-off rails that can be infinitely adjusted in length. You can adjust it without tools using wing nuts.

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Category:

Garden design