Damp proofing

A horizontal barrier or horizontal sealing prevents soil moisture from capillary rise in the masonry. In new construction, a horizontal barrier is installed as standard, but in older buildings it is often leaking or non-existent.

Types

Basically, there are three methods: the mechanical, chemical and electro physical processes.

• In the mechanical seal horizontal mechanical locking, for example, from wall cardboard, stainless steel sheets, plastic sheets and films are placed over the brickwork cross-section in order to prevent the spread of water. These are usually introduced during the construction phase.
• In the chemical Horizontal seal is subsequently introduced by injection method suitable materials in the masonry and thus reduced the moisture from spreading.
• In electrophysical dehumidification of electroosmosis is attempted to prevent the effects of moisture in the walls due to the principle. Their effect is controversial.

Design of new buildings

As a horizontal barrier mostly come bitumen sheets or thick films are used. These must on a smooth surface ( such as a mortar layer) to be laid; it is important to ensure that overlap the tracks at the joints sufficient. In buildings without cellars often two or three horizontal barriers to be fixed: the first on the foundation and the top above the soil (below the basement ceiling ) so that splash only below this barrier may impinge on the wall.

Leaking horizontal barrier

A leaky horizontal barrier leads to capillary rising damp in masonry. This in turn brings moisture damage such as mold or dry rot and the like with them. Furthermore, the thermal conductivity decreases with increasing moisture to ( the insulation is worse). Due to the lower wall temperature can in the winter condensation on the walls, this will be a further increase in the moisture.

Subsequent horizontal barrier

A horizontal barrier can also be introduced subsequently. There are, depending on the degree of saturation and building materials various methods.

Saw-

Saw- When the masonry is cut in a groove in sections of about one meter and there are PE fiberglass or stainless steel plates inserted. The plates are then wedged in the cut and sealed the cuts again. The mechanical lock the moisture is prevented in the long term from rising in the masonry. May be a seal of the bottom is also required, which can be connected to the saw kerf with the inserted film, in order to construct a sort of tub, on the inside bottom of the well can be constructed.

Wall -exchange process

In this method, stones are worked out over a length of up to one meter from the masonry and introduced a film or bitumen sheet into the hole in the wall. Then the stones are inside the wall again. After curing of the joints, another meter of the old masonry is worked out. This in and of itself quite simple, cheap and reliable method itself is often crowned in the DIY sector of lasting success, but it is comparatively time-consuming and the statics and strength of the wall should first be examined by a specialist to determine the maximum length of a replacement section and damage such as cracking or sagging walls to avoid.

Smashing of plates

A mechanical separation is also produced in that stainless chromium steel plates ( Nirosta ) are driven in a horizontal joint. Without opening the wall, a 1.5 millimeter thick wavy plate is taken. Here a continuous mortar joint must be present. The material itself is not critical in this method. Subsidence hardly occur because the plates are taken without opening in the mortar joint. The mortar is displaced in this way up and down or compacted. The fine strokes can affect the entire masonry, so that under certain circumstances, small cracks at the house. To reduce the displacement, and compression resistance, stainless steel plates have been used for some time, the wedge - or. are arrow-shaped deformed or pointed. Wherein the penetration speed is increased.

Core method

In this method, holes are drilled with a diameter of eight to ten centimeters, and then filled with a dense mortar. The holes are placed so that they overlap, that after completion of the work, a continuous barrier layer.

Injection method

So that moisture in the masonry can be transported by capillary action, an injection material is inserted into the masonry structure; This is done by holes having a diameter of about one centimeter, which can be drilled at intervals of 10 to about 25 centimeters and a depth of approximately 2/ 3 of the wall thickness. The objective of this measure is that the injection material is distributed over the entire cross-section of the masonry. This substance is intended the pores of the masonry either permanently clogged or make waterproof the walls of the pores of building materials by a hydrophobic " coating ". Thus, no capillary water transport longer take place and the overlying masonry to dry.

A distinction is made between methods with and without pressure. In the former case, the injection material under pressure up to 13 bar is injected into the masonry, in the second case it will only penetrate under the effect of gravity and by capillary action into the pores of the masonry; the holes are drilled to a downward position. When the injection material is a hydrophobic liquid and is introduced only by pressure, resulting especially in old masonry is the problem that the liquid spreads only in joints and larger cavities, but only a small part enters the water-filled capillaries and thus no continuous barrier layer forms.

The injection material

Alkali metal silicates are used for, also known as silicification process; they can also be introduced without pressure or with low pressure. The application must be repeated under certain circumstances, after a few years. Verkieselungsprodukte are alkaline and carry the danger signs "corrosive ". Dealing with them is therefore one taking the necessary precautions and the use of appropriate protective clothing.

When heated liquid paraffin used as an injection material, this affects porenverstopfend. There is also paraffin oils with dissolved plastics. Silicone microemulsions contrast, act hydrophobic effect.

There are also colored injection materials available so that someone can check with the help of control drilling the distribution of the substance.

The introduction, the effects and limits of application of the method or different injection materials are described in the brought out by the Scientific and Technical Association for Building Preservation and Conservation WTA data sheet 4-4-04 / D " masonry against capillary moisture injections ". The leaflet includes, among other things, to the fact that not every injection substance is universally applicable, but the injection of the different injection materials, depending on the degree of saturation, the capillarity of the building material and the thickness etc. building materials specific to plan and implement, in order to achieve success. According to the WTA data sheet of the manufacturer of the injection material can get a WTA certificate from a laboratory. If the injection substance the test, so he gets then a so-called WTA Wirkungsprüfzertifikat with the indication of the injected Durchfeuchtungsgrades building material, for which he has passed the test.

Execution at high moisture

Crucial for the efficiency of a non-pressurized injection borehole is the degree of saturation of the masonry and the resulting amount of injection material. However, if a Baustoffpore example, filled to more than 95 percent capillary with water so there is no sufficient residual volume to accommodate injection substance can. An injection into such a moistened building materials is thus ineffective without preparatory measures, ie the pores must be freed from the water first. This can be done by the so-called pre-drying, which precedes the actual injection. Thereby electrically operated heating elements are introduced into the drill holes and heats the walls through this to a temperature of about 110 ° C. In this heating process that exists in the material pores water evaporates in the later injection level. Thus, in the subsequent injection is the total pore volume for receiving the unpressurized injection substance available. A pre-drying is necessary, for example, so that the building materials can absorb paraffin oil.

Electro-osmosis method

The electro-osmosis process is not a horizontal barrier in the strict sense, but is based according to the specifications of the supplier on the physical principle of electroosmosis. The effectiveness was not confirmed by scientific studies. For details see Electrophysical Mauertrockenlegung under the keyword.