Dry a cellar professionally

Many homeowners know it only too well. The cellar is often a not to be underestimated weak point, which refers to rising damp in the basement walls and wet basements in general. But draining a cellar depends on many factors. Not always the handyman should lend a hand here. Therefore, below we have compiled important information for you to drain a cellar.

The cellar historically considered

Buildings are on dirt, always. To understand why old cellars are often very wet, you have to go back a bit in the history of building. Not always had the craftsmen so excellent construction and sealants as today. Even in the last 60 years, there were still huge deficits. For many centuries, the construction of the house and cellar was characterized by a wealth of experience, which was passed on from one to the next generation of craftsmen.

The house construction was perfectly coordinated

After moisture always moves into buildings, no attempt was made to completely seal a house from the basement. Rather, the house construction was adapted to these requirements. The entire house structure from the basement to the facades and windows to the roof are fine-tuned. Old cellars usually have a loose floor through which the moisture can rise.

The ventilation of the house starts in the basement

Leaking basement windows provided ample ventilation and dehumidification. The moisture rising further into the house was channeled outside via the diffusion-permeable outer walls (including their protective layer in the form of plasters and paints) as well as via windows that were also not properly sealed. The final venting and drainage of a house took place via a cold roof.

Today can not be built anymore

However, this design is no longer feasible today, is also contrary to the claims. Alone, the energy costs for such a poorly insulated house would be exorbitantly high. Also, according to the EnEV not allowed. However, deliberate house insulation has increased more and more explicitly in the past 30 to 40 years.

  • wall insulation
  • roof insulation
  • Dämmfenster
  • high-attenuation windows
  • modern, high insulation ETICS

Especially in the last decades many mistakes

Even back in the 1990s just old houses, but were built according to the above principle, suddenly partially insulated with special windows, the cellars were often converted into living space. The result was often a strong mold, because the entire ventilation and drainage system of a house was destroyed.

The insulation always begins with the cellar drying

Therefore, a basement wall is drained today after numerous factors. The building materials used play a role as well as the wetness properties of the surrounding soil. So it has to be established that groundwater presses against the house, whether rainwater runs off quickly or whether water is stored in the ground for a long time. Because Keller itself can seal you differently.

  • vertical sealing
  • horizontal sealing

The horizontal drainage

The horizontal seal is missing especially in older houses mostly. This creates a barrier on which the house stands later. In the 1980s, this barrier layer was often introduced after the first row of cellar stones, and then proceeded to the next stone layer. Different materials such as stainless steel sheets or bituminous sheets can be considered for this.

The vertical cellar seal

The vertical cellar sealing has been carried out for some time. The aim is to seal the outer walls of the basement to the base. For older houses tar was used for this purpose, which decomposes however over the decades. Modern seals consist of a plastic-coated bitumen.

The vertical seal consists of several elements

In addition, a plaster layer is applied, which is also adapted in their vapor permeability to the respective needs. For with the water also salts penetrate into the masonry and provide additional damage. Finally, a perimeter insulation for thermal insulation can be applied to these layers.

The construction of the vertical cellar drywall

The drainage and sealing of the exposed basement walls thus takes place in a specific order from the inside to the outside (outer wall).

  • Completely expose masonry and allow to dry (sometimes over weeks)
  • remove old plaster if necessary
  • Apply barrier and primer
  • Plastering (mostly with P3 classification)
  • Bituminous paint (plastic-coated)
  • perimeter insulation
Take equal account on this occasion

In addition, it may well be useful to check the drainage on this occasion. Whether it is present or if it is still intact.

The horizontal drainage

The horizontal draining or sealing can also be carried out in the piece by piece, the release layer (steel, bituminous sheet, etc.) is introduced. This work can be done from inside as well as from outside.

Tips & Tricks

In recent years, horizontal draining and waterproofing have become increasingly popular with injections. However, compared to the previously described horizontal seal, this only provides an efficiency of between 60 and 80 percent, whereby the costs can be approximately the same (around 200 euros per square meter for a high quality basement wall injection). However, the success of the injection also depends on the condition of the brickwork from. The injection seal is a capillary-based seal. If the capillary system of the masonry is now filled with water due to heavy moisture in the basement, the injection seal can not penetrate into the capillary system and therefore can not seal. Accordingly, additional work such as plaster removal and the lengthy draining of the basement walls are often added.

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