The waterproofing and drainage of a building - a real challenge

A basement has to do a lot. Regardless of whether the basement is used as living space, to store personal items or to house important building services such as for example the heating system. At the same time, the basement has to withstand numerous requirements: the load on the floors that build on it, the lateral earth pressure and, in particular, the water loads in the form of surface, facade, seepage, stratum, backwater, and groundwater.

Water finds its way and causes its damage

A slightly musty smell, peeling plaster or mould growth are typical signs of a damp basement. The main cause of it is an insufficient or incorrectly executed sealing. Because water finds many ways into the masonry and even “wanders” through concrete. Rising damp from the foundation impairs the use of the basements and may rise to the apartment of the ground floor. The consequences are the formation of mould and mould spores in the room air. These, in turn, are hazardous to health because they may trigger many diseases and allergies. Furthermore, the damp walls give off moisture to the air. The result is an unhealthy indoor climate. The water inside the walls damages the various functional layers inside the wall structure such as the interior and exterior plaster and of course the thermal insulation. In addition to the potential damage to the masonry, a considerable amount of energy is lost as well.

For this reason, a basement must be properly sealed - otherwise there is a risk of moisture damage resulting in mould and even in the impairment of the building's statics. This is why the subject relating to the “foundation protection” is of central importance for both homeowners and builders.

The solutions by DELTA®

The basement products of the brand DELTA® offer flexible system solutions for the protection and drainage of foundation walls. We only use high-quality materials whereby this is noticeable in the service life as well as in the functionality of our products. The wall barrier membranes by DELTA® such as DELTA®-SOFTFLEXX offer an effective protection of the masonry against the rising damp and are supplemented by the DELTA®-THENE, sealing of building which can also be used as radon sealing. The sealing protection is provided by the protective and drainage membranes by DELTA® such as DELTA®-GEO DRAIN QUATTRO und DELTA®-TERRAXX offering a tested long-term durability of 100 years!

A fundamental problem: a damp basement

Basements are entirely or at least partially positioned in the moist soil. For this reason, the basements and/or components being in touch with the ground must at least be sealed against soil moisture. Depending on the nature of the subsoil - for example, in the case of groundwater and the risk of standing seepage water - a higher-quality sealing and an integration in the form of a surface drainage may be needed.

A building site appraiser provides information concerning the characteristic of the soil. If, for example, stratified water is found in the subsoil, this may result in laterally pressing water on the outer wall of the basement. A properly planned sealing connected to a surface drainage covering the whole basement protects against leaks. Older buildings, however, do not have the suitable sealing measures. In many cases, the cross-section seals (masonry barriers) are missing inside the walls. This can result in moisture problems caused by capillary rising moisture. Or only a tar or bitumen coating was used as sealing. These days, however, such seals are no longer professional because the basement rooms are being used in an increasingly more sophisticated way so that moisture cannot be accepted any longer inside the basement.

A suitable sealing of the basement

While acute problems such as leaks or mould growth require a quick action, the sealing of the basement can be planned in advance in the context of new construction or renovation measures. Regardless of whether it is a new building or a renovation: A high-performance sealing always plays its crucial role.

Vertikale Anwendung von DELTA®-THENE

The basement sealing is the main component of the basement protection. It should always be tailored to the individual requirements of the environment and planned with care. For this purpose, first of all, the existing soil conditions must be clarified. In addition to the load-bearing capacity of the subsoil, its seepage capacity, the existence of water veins or the height of the groundwater level are explored and inspected in the context of a subsoil survey.

If the basement is based on a floor slab made of normal reinforced concrete with basement walls built on top of it, all surfaces being in touch with the ground must be sealed according to the water action (formerly also referred to as "load case"). A so-called "black tank" can be used in case of the water or groundwater pressure. This is usually a multi-layer bituminous membrane seal entirely enclosing the basement, including the floor slab, from the outside.

As an alternative, a so-called "white tub" can be planned as well. In this case, the basement is made entirely of waterproof concrete (in German, the so-called WU Beton). In addition to a special concrete mix, in this context what particularly counts, is the reinforcement. This must ensure that crack widths are limited to a permissible minimum due to the shrinkage process of the concrete. In the area of the joints between individual components and/or between the walls and the floor slab, the sealing is carried out by using sealing tapes in the concrete.

In the case of soil conditions such as soil moisture or seepage water, a traditional sealing will suffice. This type of sealing includes the sealing of the floor slab, the cross-sectional seals (horizontal barrier or masonry barrier) inside the walls and the sealing of the outer walls of the basement.

The type of sealing of the basement also determines the construction type of the basement itself.

Other causes of moisture problems in the basement are, for example, high levels of moisture from the laundry rooms or water damage caused by defective and leaky pipes.

Even if a damp basement wall isn't always noticeable by water stains or a musty smell, there may be moisture inside the wall. For this reason, it is advisable to obtain an expert opinion on the condition of the basement walls. If in this context wetness or moisture is discovered, this means that you have to address the causes instead of carrying out a superficial treatment.

A professional renovation of the basement sealing is urgently required.

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