Leca® KERAMZYT - the way to drainage.
Continuous development of construction results in a systematic reduction of attractive land for development. Therefore, many times investors decide to build in difficult soil and water conditions. There is a problem with the foundation of the building and proper protection against groundwater and rainwater. Also, prolonged and heavy rainfall can cause situations when a previously used object is flooded by water. In such circumstances it is worth considering drainage.
What is drainage?
In the simplest terms, drainage can be defined as a system of collecting and draining water from the ground. It can apply to both the drainage of the building itself and the entire surrounding area. It is part of the protection of the building from moisture. In particular, the foundation walls, basement and ground floor, as well as floors on the ground. It is used most often when waterproofing alone may be insufficient.
When is drainage needed?
The shortest answer is - when water can directly threaten the foundation walls, basement or floor on the ground. This happens in areas where there is a high groundwater level, which periodically can still rise due to snowmelt and prolonged rainfall. These risks are facilitated by the presence of impermeable or semipermeable soils (e.g., clay, silt) at the location of the building.
However, the final answer to the question of whether drainage is needed will be provided by geotechnical studies, which will determine the type of subsoil and the maximum level of groundwater. The hydrogeological characteristics of the site obtained from the survey, supplemented, if possible, by archival data, allows the proper design of drainage.
Drainage helps to properly protect against the effects of groundwater and rainwater
© Leca
The need for drainage applies mainly to basement buildings built in difficult soil and water conditions and buildings located on the slopes of a hill. It also happens that a change in water conditions raises the groundwater level, which begins to threaten existing, previously dry facilities.
Note that the building's surroundings must provide for drainage or infiltration of drainage water. If there is nowhere to remove excess water, just making a drain will not help.
Construction and operation of drainage
The basic element of the drainage is a filter layer made of coarse aggregate. Its task is to ensure the free flow of groundwater and rainwater to the drainage pipe system, and further to the receiver, such as a drainage ditch, absorption well, seepage system, pond or, as a last resort, to the sewer system. The drainage must be laid with an appropriate slope (about 0.5%) so as to ensure free drainage of water in the direction of the planned outlet.
Correctly designed and constructed drainage lowers the water table to the level of the location of drainage pipes and effectively drains water from the building environment, ensuring its protection from moisture. At the same time, it should be remembered that despite the implementation of drainage, proper waterproofing of basement walls is necessary.
Note: Do not place drainage pipes below the foundation level of the building (the exception is the so-called offset drainage - 2-3 m away from the building).
Filter layer
An excellent material for making a filter layer is Leca® KERAMZYT building L. This is a lightweight ceramic aggregate with a grain size of 10-20 mm, which is characterized by a high filtration coefficient, that is, a flow velocity of 3.33 cm/s (k = 3.33‧10-2 m/s).
An additional advantage of expanded clay is its high thermal insulation, which allows to combine the drainage function with thermal insulation. At the same time it is a lightweight material, more than 6 times lighter than gravel, which makes the work itself and transportation easier.
Keramzyt combines the drainage function with thermal insulation
© Leca
Implementation of the drainage involves making a trench, which is lined with a separation geotextile separ ating the native soil from the filter layer to avoid silting up the drainage by fine soil particles.
Next, about 10 cm of expanded clay aggregate is spread on the bottom of the excavation, drainage pipes are laid on top of it , maintaining the appropriate gradients, and the excavation is filled with Leca® KERAMZIT Construction L. It is laid in layers about 30 cm thick, which should be compacted each time using a hand rammer with a 40 × 40 cm plate. Finally, the filter layer is covered with a geotextile, the sub-base is made and the pavement is laid.
EXAMPLES OF SOLUTIONS
Banded drainage
It is made along the contour of the building along the footings. Drainage pipes are usually laid right at the footings, below the horizontal insulation of the foundation walls or basements, but absolutely above the foundation level of the building. It is necessary to maintain the appropriate gradients, so that the water can flow unhindered by gravity to the intended recipients.
Banded drainage
© Leca
Underfloor drainage
In a situation where it is not possible to make a band drainage (for example, in terraced housing), an internal drain age can be made under the basement floor. It consists of a system of drainage pipes laid parallel to each other in expanded clay backfill. The pipes are laid along the walls and on the remaining surface at a distance of 0.8-1.4 m, preferably parallel to the shorter side of the building. Internal drainage can function as a stand-alone solution or in conjunction with external band drainage.
Floor drainage
© Leca
Drainage of a building on a slope
The implementation of drainage for a building located on a slope should be considered a necessity and regardless of the type of soil present. This is because there is a serious risk of retention of flowing water along the foundation wall of the building. In these circumstances, the danger is not only the risk of dampness of the elements of the building, but, above all, the soaking of the soil. This can cause excessive settlement of the building and, in extreme cases, even its landslide. To protect against this, it is enough to make drainage on the side of the hill.
Drainage of a building on a slope
© Leca
French drainage
This is a type of drainage made without pipes. The arrangement of such a drainage comes down to filling a linear excavation with Leca® KERAMZYT building L tightly wrapped in geotextile. With this method, even large areas can be drained easily and inexpensively. Such highly efficient linear drainage can be an excellent complement to a building's drainage system.
French drainage
© Leca
Plan drainage with caution!
When planning the drainage of existing buildings, it is important to consult with the constructor and geotechnical engineer, because in some cases a change in water conditions can change the bearing capacity of the soil (this applies mainly to cohesive soils) within the foundation area, which can lead to excessive and uneven settlement and consequently damage to the building. The method and timing of the work should also be agreed with the builder. Digging up too large a section of the foundation wall at once can end in a building disaster.
Prevention
Drainage of a newly constructed building can be a kind of preventive measure. This is because there is no guarantee that the groundwater level will not rise in the future and the need for drainage will arise. It is definitely better and cheaper to carry it out at the construction stage. It will be such an insurance policy at a promotional price.
Formore information, visit the company 'sLECA POLSKA Sp. z o.o. page on thePdD portal.
