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How to build a terrace on a sloping ground?

Do you want to lay a terrace on pedestals on uneven ground or on sloping ground? Whether it is a wooden terrace or a paving terrace, terrace pedestals are the solution to allow you to catch up with the height and ensure that your terrace is flat. To find out how to build your terrace on pedestals on uneven ground and even on sloping and steep terrain, discover our article!

Laying a deck on a sloping surface

Whether it is a concrete paving, loose soil or a surface covered with gravel; your ground surface is not completely straight? This is a good thing ! Yes, it is recommended to tilt your paving slightly to facilitate the evacuation of rainwater under the terrace. Imagine a concrete paving or a completely straight surface would be a bad choice because it would lead to stagnation of water and premature deterioration of the foundations of your terrace. Moreover, the DTU mentions it perfectly, it is indeed recommended to apply a slope of 1% per meter, which is equivalent to 1 cm of slope per meter of terrace.

Lay a wooden terrace on a sloping ground

To catch up the height and lay a very flat wooden terrace, there are two solutions :

  • Notched wedges
  • The adjustable pedestals

Notched wedges for laying a wooden deck

The notched wedges are available in 4 wedges of different colors and sizes. Made of high density polyethylene, these wedges are very resistant and allow vertical leveling of your joists. Thus, gain up to 85 mm by juxtaposing two black and yellow notched wedges. For optimal stability, you can of course screw them, nail them or glue them. Thanks to these wedges, which are always used in pairs, you can raise your joists in no time and adjust your terrace to the right height. This is a safe and economical solution for building your wooden terrace on sloping ground. Note: install shims every 50 cm on the joists concerned in order to guarantee the stability of the foundations.

Adjustable pedestals to make up for a height between 8 and 358 mm

For the installation of your wooden terrace, opt for terrace pedestals! Easy to use, they are also stable and resistant. The particularity of adjustable pedestals is that they adjust to the nearest millimeter to level your terrace. In addition, if you choose self-leveling them, they will catch up to 5% of the slope over 1 meter.

For the installation of your wooden terrace on a sloping ground, you just have to calculate the necessary heights of your different pedestals without forgetting to take into account the height of the joists and the blades in order to obtain a level wooden terrace, flat and adapted to your home but also to your sloping terrain.

The different heights vary according to the brands of pedestals. Note that the lowest height will be at YEED (ex Rinno) (8/20 mm) and the highest at Profilitec 328/358 mm. One thing to remember: you cannot mix cone brands with each other. It is therefore up to you to compare the different manufacturers and choose the one that will make your project feasible.

Lay a wooden terrace on a steeply sloping ground

For steep terrain, nothing better than laying a terrace on foundation screws! This type of terrace rests on tall posts called piles. The leading brand in this market is Weasyfix. For the installation of a terrace on foundation screws, we recommend that you call on a craftsman whose job it is. If you are a careful do-it-yourselfer and follow the instructions to the letter, you can get started, but don't forget to take all the necessary precautions and learn about the different steps to follow.

Building a wooden deck on Weasyfix foundation screws

First of all, do not forget to make a layout that will allow you to visualize all the elements necessary for the realization of your wooden terrace.

Weasyfix foundation screws are large screws ranging from 550mm to 1750mm in length. Made of galvanized steel, they are very robust and can support weights of up to 1 ton! By choosing Weasyfix foundation screws, you support the structure of your wooden terrace without using adjustable pedestals or, more complicated, creating a terrace on stilts.

  • Laying a wooden deck on sloping ground with Weasyfix foundation screws takes place in four steps:
  • Place your foundation screws in your ground at the rate of one screw for 2 m2. Remember to choose different pile sizes depending on the slope of your land. Be sure to align their locations and heights to obtain a flat terrace. Please note, your Weasyfix foundation screw must be at least 70 cm deep.
  • Install joists over your foundation screws. To be placed perpendicular to your joists.
  • Place your joists on the joists.
  • Install your wooden boards on your joists.

Now your terrace is ready to welcome you! 

terrasse bois surélevée sur vis de fondation weasyfix
hommes fixant les vis de fondation dans sol pentu
terrasse bois vue de plongée pour entrevoir les vis de fondation

Lay a paving terrace on a sloping ground

Two solutions allow you to create an outdoor tiled terrace on sloping ground:

  • The adjustable pedestals
  • Foundation screws or Weasyfix piles

Adjustable paving pedestals to compensate for a height between 8 and 358 mm

As with wooden terrace pedestals, paving pedestals make it possible to make up for different heights. From 8 mm at Rinno, from 10 mm at Jouplast, from 20 mm at Vérindal, from 28 mm at Profilitec… the heights of the pedestals are variable and above all adjustable to the nearest millimeter in order to adapt to your sloping ground. And as with wood, the self-leveling paving pedestals will allow you to catch up to 5% additional slope. This is an economical, quick and practical solution for building your terrace on pedestals on moderately sloping ground.

Building an outdoor tiled terrace on Weasyfix foundation screws is possible!

Weasyfix foundation screws are also compatible with exterior tiling. Indeed, Weasyfix has developed galvanized steel structures that allow the installation of porcelain stoneware terraces. The installation is quick and the accessories allow for a perfect finish. Better you can install your porcelain stoneware terrace in aligned or staggered pose. Since the foundation screws are made of magnelised steel, their lifespan is optimal. Adjustments are simple as all components are bolted.

Laying a porcelain stoneware terrace on Weasyfix piles is done as follows :

  1. Start by making the pilot holes
  2. Install your foundation screws & connectors
  3. Lay the lower structure
  4. Lay the upper structure
  5. Install paving supports
  6. Lay your porcelain stoneware tiles.

Your terrace with foundation screws is now ready to welcome you!

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