When building a house on a site with a high level of groundwater, on clay soil or when planning basements with a large depth, one must take into account the danger of underflooding the foundation. Its probability increases with a large amount of precipitation, a small slope on the site, an incorrect calculation of the discharge of waste water. Even irregular and uninfluenced flooding can have an extremely negative impact on the strength of the foundation, cause dampness and mold and lead to the destruction of the house. You can protect the building by equipping the foundation of the house.
For houses located on sandy ground, not freezing over 80 cm, the construction of drainage is not required, but thorough waterproofing of the foundation is a must.
Which drainage is suitable?
Around the house with the used basement or basement rooms, a wall drain is required. It is excavated around the basement and is equipped with manholes in the corners. The construction of such a drainage should be taken care of even during the erection of the foundation, so after the completion of construction it will be much more difficult and more expensive.
If the house does not have a deep basement, it is possible to construct a trench( ring) drainage at a distance of one and a half to three meters from the foundation with an additional protective layer of clay. The same trenches can also be used for storm sewers.
Preparation and selection of materials
Before excavation, you need to determine the required material.
- To date, pipes from PVC or polypropylene for drainage are the best option. They are light, not subject to corrosion due to the action of groundwater, and the installation of such a drain is simple. Specialized drainage pipes have a diameter of 11 cm and perforation of a part of the surface in the form of two wide longitudinal strips. You can use cheaper tubes without perforation, drill evenly with a drill hole in several rows at a distance of 6 cm from each other. It should be noted that in the future the pipes should be located so that the holes are on the sides. Between each other the pipes are connected by couplings.
- geotextile is used to protect pipes from clogging, it is also used as a rubble pad, preventing rapid siltation. It is a membrane that draws water to the pipes, but detains large particles.
- To monitor the condition of the drainage system and, if necessary, to wash it, in certain places it is necessary to install inspection wells. Their number is equal to the number of turns in the system plus one in the place of draining the water.
Begin the laying of drainage with a thorough waterproofing of the foundation. It must be treated with bituminous primer, and then apply the mastic in two layers, placing between them a reinforcing mesh with cells 2 * 2 cm. The second layer of mastic is applied only after the previous one has dried, not earlier than in 24 hours.
Earthwork
Before trenching a trench is dug along the walls of the house at a distance of about a meter from them or from the blind, if any. In advance, with the help of a level, it is necessary to find the lowest point of the basement, in this corner the uppermost part of the drainage will be located. It is better to excavate trenches from this point, deepening them so that the pipes run at an inclination of about 1 cm for every 2 meters, so that water does not accumulate, but can drain. Slope may be greater if the site is often flooded or groundwater is close to the surface.
The width of the trench should be such that the pipe and the layer of crushed stone are placed 10 cm around it, that is, about 30 cm. A layer of sand 5-10 cm thick is poured onto the bottom of the pit. The geotextile layer is laid on the sand so that its ends extend beyond the wallstrenches evenly on both sides. A layer of crushed stone of fraction 20-40 with a thickness of 10 cm is poured on top of the top.
Pipe laying
After completing the preparatory work, you can begin laying pipes wrapped in a layer of geotextile, constantly monitoring with the help of the level, whether the required gradient is observed. In the corners bends are made at an angle of 45 degrees, from which the inspection wells, which are closed by lids, then rise to the surface. The well should not be located at the very turn, but not further than 20 m from it, on the direct same sections of the audit are located every 40 m.
Padded pipes on the sides and top are covered with a layer of crushed stone. Then, the free ends of the geotextile are lapped over it, as if wrapping the whole pie. The ends of the fabric are sewn or fixed with metal clips. From above, the geotextile is covered with a layer of sand, which in itself is a drainage.
At the lowest point of the drainage system, a water receiver is connected to it. For this, a deep pit is dug, the bottom of which is lined with geotextile, a container is installed in it, for example a plastic barrel, along the bottom edge of which a series of holes is made. The drainage well can be constructed of concrete rings( as described here) or cast from concrete. It will drain water from the system. On top of the drainage well should be tightly closed with a hatch, it is desirable that it was also insulated with foam.
Correctly executed drainage will secure the foundation of the house from undermining, will avoid the occurrence of mold on it and increase the service life of the entire structure.
