Causes of leaks in the elevator shaft and garage. Risks to the building as a result and some possible solutions.
For a start, it is good to get acquainted with the purpose of elevator shafts. Apart from being a vertical communication for the flow of people between the floors, they are often the supporting core of a reinforced concrete structure - the so-called earthquake washers. Washers and support columns are located on the dividing lines of the garages, as well as on their bottom. Issues related to the design of vertical load-bearing elements, their implementation and proper operation are of paramount importance for the security of the building! Therefore, they should be considered as a priority, regardless of the purpose of the structure. Compromises in any of the above three stages can lead to severe consequences and even accidents in the future. In our daily lives, however, we often witness leaks in basements, underground parking lots, garages and elevator shafts. The lack of underground waterproofing or its poor performance is the cause of leaks even in newly built buildings. A prerequisite for this is the naturally high level of groundwater in many Bulgarian cities, the reason for the "flooding" of the shafts and flooding of garages and basements.
Due to the location of the elevator shafts, usually around the geometric center of the building, the repair of the external waterproofing in this section becomes practically impossible.
Английски Povecheto firmi predlagat polaganeto na vŭtreshna izolatsiya pod razlichni formi ili dopŭlnitelnoto izgrazhdane na khidroforna uredba. Na prŭv pogled tezi resheniya eliminirat pochti napŭlno problema s vodata, koyato se prosmukva prez stenite i poda. Na praktika obache, te zashtitavat edinstveno asans’ornata uredba, kato dori vloshavat situatsiyata v koyato se namira konstruktsiyata. Visokata vlazhnost s vremeto stava prichina za znachitelno namalyavane na fiziko-mekhanichnite svoĭstva na gradivnite materiali i kompromentira konstruktsiyata. Sŭshto taka predizvikva seriozna koroziya v elementite na asans’ornata uredba. Most companies offer the laying of internal insulation in various forms or the additional construction of a hydrophore system. At first glance, these solutions almost completely eliminate the problem of water seeping through the walls and floor. In practice, however, they only protect the elevator system, even worsening the situation in which the structure is located. High humidity over time causes a significant reduction in the physical and mechanical properties of building materials and compromises the structure. It also causes serious corrosion in the elements of the elevator system.
Additional internal waterproofing
Let's first consider the application of additional, internal waterproofing on the walls and floor. Even qualitatively executed, this waterproofing often does not create sufficient watertightness around the structural connections of the elevator system with the structure - anchors, plates. Not long after, the leak situation repeats itself.
Another major drawback is the sealing of the water inside the load-bearing walls, which are very often earthquake washers. And right at their base, where they are extremely busy. Through the internal waterproofing we artificially create conditions for retention and capillary rise of water in the height of the shaft.
An improved version of the internal waterproofing is the implementation of waterproof screed on the bottom, which prevents the penetration of water between the bottom-wall joint. Pre-impregnation of the walls improves their water tightness and to some extent limits the capillary rise of water.
The implementation of these systems is complex and requires strict monitoring of the implementation technology. The installation of water-swellable tapes and injection hoses increases the reliability and maintainability of this system. It is applied at long leaks and serious degradation of concrete and reinforcement.
Hydrophore system in the elevator shaft
This method can eliminate the problem of "boiling", but the high humidity in the walls and floor of the structure remains.
As an additional effect of the continuous pumping of water, there is an extraction of calcium hydroxide (portlandite) from the structure of the cement stone (so-called corrosion type 1), as well as sulfate corrosion, which reduces the strength of concrete. It also reduces its hydrogen index (pH), which otherwise prevents corrosion in the reinforcement. This method can be defined as the most undesirable and harmful to the structure.
Local sealing of affected areas with weak concrete
A relatively fast and efficient method is the local sealing of areas affected by strong corrosion in concrete and reinforcement. Weakened concrete is removed, and in cases of affected longitudinal reinforcement, it is necessary to replace it. This is followed by installation of an injection hose, reinforcement, formwork and concreting of the site.
To achieve a watertight barrier, special concrete compositions and strict execution of the work process are used. The implementation of this system carries the risk of killing a high-flow leak during the preparatory activities including the removal of concrete and reinforcement from the affected areas.
What can be done to avoid these undesirable consequences of conventional waterproofing systems?
Here is the place to emphasize the mandatory involvement of a highly qualified specialist both in the research and design activities and during the implementation itself. His participation will ensure the successful and safe solution of a complex and individual construction task like this. The options for action are many and can be determined only after a more in-depth analysis of the causes that led to the problem. Linking to a company specializing in one type of activity most often leads to the implementation of its system, without a guarantee for an optimal solution. In general and conditionally according to the specific site, the following steps can be taken:
First step - a study to select a qualified specialist to assess the situation. This step sets the direction for further action and at the same time can save a lot of money, time and unnecessary activities. Consultation is the lowest cost of eliminating such a problem.
Second step - to give a definite answer about the level, the nature of the groundwater and the possibilities for their reduction. If necessary, to inspect the structural elements affected by moisture to determine their current state.
Third step - to apply simple and easy measures to deal with the problem. Such are diagnostics of the internal plumbing installation, replacement and discharge of the gutters from the roof and others.
Fourth step -in the absence or insufficient result of the above activities, proceed to the diagnosis of the external plumbing installation of the building, provided that the leak is year-round.
Fifth step - for each specific site, is the implementation of one or more measures such as a drainage system with or without a hydrophore, partial replacement of an external HI, injection of resins and solutions directly into the structure.
Waterproofing injections
The injection method is particularly effective in the case of local moisture or leakage in wall or floor elements and especially in the connection between them. Its main advantages are the created water tightness in the whole section of the element, the protection of the reinforcement from corrosion, the fast execution without the need for breaking, deformability after connection. Polyurethane resins have an extremely long service life - as long as the life of the building. Another advantage of polyurethane is that it does not harm the environment and humans. The disadvantages are the complexity of the operations and the need for special pumps. This technology is applicable to concretes with sufficient mechanical properties. Continuous control and participation by specialists in the field is mandatory.
Additional drainage system
The construction of an additional drainage system, reducing the water level under the foundations of the building, is also an often applied, efficient solution, but it hides its risks. In many cases, when the drainage is completed without the obligatory intervention of a geologist, it does not function well enough, after some time it becomes clogged or causes the collapse of earth layers due to hydraulic destruction of the soil.
The drainage system locally lowers the groundwater level under the building:
When the level of the drainage system is below that of the street sewerage network, the additional installation of a hydrophore is required.
The drainage system is a very suitable, but not universal, approach. Its higher price can be justified by solving a complex of problems related to the high groundwater around the building.
Waterproofing of underground parking lots, garages and basements
Waterproofing leaky or damp walls and joints of underground parts of the building is a large venture. It is possible to apply different techniques in different parts of the building. The ultimate goal is to protect the building and significantly reduce the humidity in its premises.
These elements imply the use of more economical materials and technologies. In most cases, gradual treatment of leaks is applied. The first stage is sealing the active leaks in cracks and joints between the elements. This can be done by coating with fast setting cements or injection with polyurethane polymers. After a reliable stop of the water, a deeply penetrating impregnating agent is applied on the concrete surface. The third stage is the application of greased, high-tech cement-based plaster.
Sometimes the solution turns out to be simple and does not require expensive interventions. However, untimely intervention on problems with leaks and moisture inevitably leads to property damage, endangering the safety of occupants, the need for complex and expensive repairs to the structure and elevator system, reducing the life of the building and aesthetic defects.