Modern residential buildings have very high requirements for the quality of the used building materials and the reliability of the adopted technical solutions.
Sometimes in new buildings, various systems fail during the initial period of operation of the building. As a result, the initial investment is supplemented by repair costs, which are comparable to the cost of the construction itself.
In most cases, the first problem after the construction of the house is a leaky basement. This happens due to an incorrectly selected external waterproofing system, or poor quality of its execution.
The foundation, and especially the basement or ground floor, are some of the most labor-intensive and expensive works in the construction of a house. Properly designed and built, it becomes the key to the durability and reliability of the entire building. And especially the foundation, like no other part of the house, needs reliable protection.
Its structure, located below ground level, is constantly exposed to water, the causes of which can be very different. This is a constantly high level of groundwater, or its seasonal increase, precipitation, or a break in the sewer pipe. Even the capillary rise of water, which under certain conditions can be more than 12 meters, affects the waterproofing of the foundation.
Contact with water destroys concrete, damages reinforcement, and causes microcracks. In addition, temperature changes should be taken into account: when water freezes, its volume increases by 9%. All these factors can gradually destroy the foundation. That is why its waterproofing is so important in modern construction. Depending on the method of installation and the materials used, the following types of foundation waterproofing are distinguished: adhesive, coating, penetrating and mounted.
In addition, there are: quick-hardening compounds for repairing emergency leaks; sanitizing plasters; water-repellent compounds for imparting water-repellent properties to concrete and brick; anti-salt, anti-fungal impregnations, etc.
Wet on wet
Coating waterproofing is perhaps the oldest, but still one of the most popular methods of combating moisture. Coating waterproofing is a multi-layer coating with a thickness from several millimeters to several centimeters. The most common materials for coating waterproofing are bitumen and bitumen-containing materials. They are cheap and easy to apply, but at a temperature of 0°C they lose elasticity and become crushable, as a result, their service life is limited to 5-6 years.
Recently, materials based on synthetic resins (polymers) and their various modifications have been increasingly used. They have higher technical characteristics and a much longer service life. The most striking representative of such materials is Remmers cold bitumen-polymer mastic, which has a number of advantages over other types of external waterproofing. It can be applied to wet bases, which is important for rainy Belarus, it is simple and technologically advanced in application, which reduces the dependence of the final result on the qualifications of workers, it is able to cover cracks and withstand the effects of waters that are aggressive for concrete. The service life, if applied correctly, can last for decades.
Gluing courses
This coating is a continuous carpet made of waterproof film or roll materials. These include: roofing felt, tar paper, parchment and representatives of the new generation, which are produced on the basis of synthetic materials (glassfiber, glasscloth, polyester).
The adhesive materials are most often sold in rolls, but there are also sheets. The method of fixation is gluing on a special mastic or fusing with an open flame. In order to avoid moisture penetration, the joints, both in the first case and in the second, are overlapped.
Practical builders note that roll waterproofing is reliable and durable, but very “capricious” in execution. It requires a carefully prepared surface – irregularities of more than 2 mm is unacceptable, a dry base, priming with bitumen emulsion, extremely careful gluing or fusing of the material are necessary. Any oversight in application can eventually turn into a hole in your basement. In case of using such waterproofing outside (with positive water pressure), it is necessary to protect it (for example, with screens, panels or geotextiles) from possible mechanical damage. Adhesive waterproofing will perform its function for many years, but for this it is necessary to involve only highly qualified personnel in the work and strictly adhere to the application technology.
Shield against water
Another waterproofing technology is the creation of protective screens. Since ancient times, compacted clay (40-50 cm layer) has been used for this purpose – a widely used and easily accessible material.
The natural development of the idea was the so-called bentonite waterproofing. Bentonite clay, which has pronounced colloidal properties, is capable of playing the role of a shield already at a thickness of 1-2 cm. The bentonite layer is enclosed between sheets of cardboard or geotextile. The cardboard shell decomposes in the soil during operation. As a result, the entire buried surface is surrounded by clay.
The domestic market offers Voltex and BENTOMAT insulation mats. The latest development in the field of protective screen technology is polymer geomembranes. Its undoubted advantages are durability, neutrality to aggressive environments, resistance to structural deformation and soil movement. The screen consists of a cloth with rounded spikes up to 8 mm in size and filter textiles. The textiles protect the system from silting with soil particles, and the rounded spikes form drainage channels through which filtered water is sent to the drainage system. This solution prevents building subsidence, provides good waterproofing of the walls, and also serves as protection for the foundation slab from capillary moisture suction. Drainage screens work successfully only in combination with a drainage system and stop functioning when the groundwater level rises above the level of the discharge pipes. This type of waterproofing has a number of advantages, but experts believe that its most rational use is for household and industrial waste dumps or for areas for storing petroleum products.
With the right choice of the required external waterproofing system and its high-quality execution, the foundation will be reliably protected from destruction and moisture penetration, but this is not always possible to achieve. At a certain stage, moisture can still penetrate into the premises and disrupt the normal operation of the building.
As a result, the problem of basement waterproofing arises again, for the solution of which you can resort to opening the foundation and repairing the waterproofing or contact suppliers of modern technologies that allow you to carry out repair work from the inside.
There is a significant difference between the arrangement of external and internal waterproofing. In the first case, the water pressure from the outside presses the waterproofing coating to the base, in the second case, it tears it away from it. Thus, to ensure reliable internal waterproofing, the used coating should meet two main conditions – good adhesion to the base and water resistance. In this type of work, the Remmers coating waterproofing system has proven itself well, which was specially developed for internal protection of the basement from water leaks. Due to the ability to apply “fresh on fresh” on any mineral bases and at any humidity, it allows to create a waterproof membrane that can withstand negative water pressure equal to 20 m of water column in the shortest possible time. As a result, a basement that was used as a warehouse can be transformed into a cozy living space.
Fix the leak!
Another option for internal basement waterproofing is penetrating waterproofing. The idea of penetrating waterproofing (penetration) was first born in Denmark in the early 1950s. Penetrating materials are made of cement with additives of chemically active substances and specially crushed sand. They are used to reduce the capillary conductivity of concrete. Additives, together with capillary moisture, penetrate through open pores into the thickness of the material, where they interact with the components of the concrete and form thread-shaped crystals. The pores are significantly narrowed, and water permeability becomes lower.
However, it should be noted that the effect of penetrating waterproofing is possible only in the capillaries of concrete or cement-sand mortar. And that penetrating compounds are good for fresh concrete. When repairing old concrete, the surface should be thoroughly cleaned of plaster and degreased, opening access to the capillary system. Moreover, a scraper or wire brush is not enough for this operation. Here, a sand-water jet apparatus operating at a pressure of at least 15-20 atm is required. It is important to note that only a single application of penetrating compounds is possible, since the substances necessary for the reaction have already reacted, and subsequent application will not lead to anything. The depth of their penetration into the concrete structure depends on many indicators, so it is impossible to calculate and thereby guarantee the effectiveness of the system. And the property of such compounds to form crystals not only in concrete, but also on its surface over time can lead to peeling of plaster, tiles or damage to the external waterproofing.
Recommendations
To successfully carry out waterproofing work on your future home, you need to strictly fulfill 3 conditions.
1. Avoid making mistakes at the design stage. Ideally, for the best choice of waterproofing material, it is necessary to conduct engineering and geological surveys. They are necessary in order to accurately determine the level and pressure of groundwater (hydraulic load).
2. Whatever type of waterproofing you choose, the work should be carried out according to technology by experienced builders.
3. Do not economize! The cost of the foundation usually makes up 15-20% of the total cost of the house, and the cost of waterproofing the foundation is only 1-3%. But miscalculations and poor quality work will inevitably require much larger investments in the future.
For information
The most commonly offered block foundations have many advantages, including high load-bearing capacity and an economically advantageous method of laying. But from the point of view of waterproofing, a monolithic foundation is preferable.
Thermal insulation of the foundation
There are often cases when a lot of effort, money and materials have been spent on waterproofing, but the basement is still damp. The reason may be condensation falling on the “cold” wall from the humid air. Therefore, the basement walls should be insulated from the outside, and ventilation should be arranged inside. You can cover the walls with special porous “warm” or sanitizing plasters that reduce steam condensation on the cold surface.
Rigid slabs made of extruded polystyrene foam, as well as foamed (porous) polystyrene foam, are used for thermal insulation of foundations.
Author: Sudenkova S., 2011.