How to professionally seal your basement

In many buildings, the basement is in the true sense of the word a permanent construction site. The basement is one of the most massive weaknesses in the house, when it comes to penetrating into the masonry water and wet to wet walls. In recent years, however, much has been done in the selection of suitable sealing materials. Below you will find detailed instructions for sealing a cellar and a lot of information about the sealing systems.

The principle of basement waterproofing is not yet old

The understanding of sealed cellar walls (and also a watertight base) did not really materialize until the last third of the 20th century. Previously, buildings in their entirety were designed so that a basement was damp from the house, but this moisture was derived throughout the house. Correspondingly many buildings have to be sealed afterwards.

  • poorly sealed basement windows
  • diffusion-permeable interior walls and paints (limestone and lime sludge)
  • not completely closed wooden windows
  • cold roofs

However, with the increasing importance of energy savings, more and more diffusion-open insulation was used. As an example, only the high-attenuation energy window is mentioned here. In addition, the requirements for basements have changed. For a long time, it has not only served for storing vegetables and as a storage room.

Old cellar seals do not have a particularly long service life

In addition, houses were to a small extent, although a cellar sealed, but which consisted of tar. But tar dissolves even more quickly on contact with water. Only in recent years have highly efficient sealing materials come on the market, which have significantly longer lifetimes and can be perfectly matched to the given situation on site.

Requirements for sealing the cellar

This is how you have to divide the soil surrounding the house according to the water holding or running properties.

  • Leachate (rainwater and meltwater) that runs off quickly
  • Leachate, which accumulates in the short term in the case of very heavy showers
  • Groundwater that is permanently pressed
  • Pressing water in case of rain due to rising groundwater
  • Earth layers that prevent the water from draining (loam layers)

The construction of a basement seal

Basically, the structure is always similar, except that the concrete tub, from which the cellar is poured, differences according to constantly or often oppressive water or fast running leachate has.

  • white bath tub or basement bath (water-impermeable WU concrete) without expansion joints, but with predetermined breaking points if pressurized water is a problem
  • black bath tub or cellar with bituminous paint and expansion joints if water always drains off

The horizontal basement waterproofing

The outer masonry or concrete walls Always experience a horizontal seal, which is usually directly above the building base and is sometimes repeated again in front of the basement ceiling. For this purpose, a barrier layer is laid in the walls, which may consist of bituminous sheets or stainless steel sheet. This barrier layer can also be retrofitted from the inside or the outside, but requires a lot of expertise.

The injection seal

Alternatively, you can also apply a horizontal barrier through injection seals. For this, the basement wall must be internally but absolutely dry and professionally sealed from the outside.

The vertical cellar sealing

From the outside, the vertical sealing takes place, that is, the cellar masonry is sealed from the outside. In addition, drainage and perimeter insulation should also be installed on this occasion. The structure results as follows on the outer wall from the inside to the outside.

  • Adhesive primer
  • Plaster (P III)
  • Special bituminous compound for sealing (up to 7 mm thick)
  • Styrofoam or Styrodur insulation boards
  • Knock-out membrane
  • Drainage

Below we describe for you the sealing of the basement from the outside, as well as the subsequent horizontal sealing can be made from the outside or for the injection barrier and the outer basement wall must be efficiently sealed.

Instructions for sealing the cellar

  • special plaster (P III, also suitable for salt)
  • primer or barrier primer
  • bitumen for sealing the cellar outside
  • styrodur or styrofoam insulation panels (perimeter insulation and, if necessary, horizontal drainage)
  • pincushion barrier (possibly also horizontal drainage)
  • Drainage pipe
  • Gravel
  • Masking tape or net
  • Mini excavator
  • Shaft supports
  • Hammer
  • Chisel
  • Various trowels
  • Cleaning-friction board
  • Drilling machine with stirrer
  • Mortar bucket
  • Possibly concrete mixer

1. Preparation

a) Excavation and securing
First of all You dig out around the building to a maximum of 30 cm below the basement base (dig deeper, this can negatively affect the statics). Then the approximately 80 cm wide shaft in which you perform all work is supported. Secure the excavated soil with appropriate films or nets.

b) Remove old loose plaster and loose joint mortar
Now old plaster must be removed, as well as joint grout that loosens. The background is that otherwise neither primer nor the new plaster stick. Ver 2. Plastering the basement walls

Now you can start plastering the basement walls. The plaster can be applied several millimeters. Then smooth the still damp plaster with a friction board. After that the plaster has to dry completely. This can take several days.

3. Seal cellar walls with bitumen

Now the special waterproofing bitumen compound is applied. Please note the manufacturer's instructions. In some cases a layer may be applied during application (ie a maximum of 4 mm, but in total it may be necessary to form a bitumen sealing layer up to 7 mm thick.) According to the manufacturer's instructions, the first layer must also dry completely before the second

4. Apply perimeter insulation and notepatch ply

Once the bitumen layer has dried completely, stick the polystyrene insulation boards back in. Use the bitumen previously used as adhesive for the reverse side Modern perimeter insulation has gradations on the side so that they can be joined with the next one N The notched ropeways are ajar with the knobs towards the wall side, the clear upper overhang is cut off after filling in.

5. Applying the drainage

Now a thin gravel bed is laid in which the drainage pipe is laid top point of the drainage may not nic ht are above the upper basement skirting. The drainage pipe, which should ideally be in a ring around the house, must have a gradient of approximately 1 percent at the lowest point. The drain is optimally located on the seepage shaft. Then a 10 to 20 cm high layer of gravel is applied over the drainage pipe. Soil would clog the perforation. Abschluss 6. Final Theses

Now refill the shaft with soil. If there was a lot of loamy soil when digging the pit, it should be replaced, as loam is extremely beneficial for backwater. Finally, the Noppensperrbahn is cut off. If you still want to do an injection sealing from the basement side, you can do that next - provided that the basement walls are already dry.

Tips & TricksThe polystyrene faceplates can be equipped with a horizontal drainage system. However, this must not be used with pressurized water. In addition, the outside can be equipped with a special filter fleece to protect against blockages. If you apply a bituminous layer up to 7 mm thick (when the water is heavy), you can place a reinforcing mesh after the first layer to reinforce it.

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