Many people have to solve the problem of how to increase the house by several meters, how to connect the new part of the house with the old one, how to make an extension so that the whole structure remains stable and reliable. In this article, we will consider the nuances of performing this type of “modernization” of the house, as well as give advice on how to correctly and competently perform it.
In order to avoid the appearance of cracks and other deformations of the structural elements of the house, it must be cut with vertical expansion joints.
Expansion joints distinguish between seismic, sedimentary and temperature.
The sedimentary seam, as it were, cuts the entire building from the very foundation to the roof ridge. It is performed in order to ensure self-shrinkage of various parts of the house in a vertical direction. Sedimentary seam must be carried out in buildings that are built from different parts (outbuildings) on the ground with different geological structure or in case of a large difference in weight of different adjoining parts of the same building. The main task is to protect both the house and its attached part from uneven subsidence.
The main cause of subsidence of soil under the foundation, as a rule, is the compaction of soil layers under the influence of the weight of the building. This process has the greatest intensity during the first year after the completion of the construction of the house box. During this period, the soil, as it were, “gets used” to the changed conditions. Settling of new foundations occurs much faster than old foundations, since under the old foundations it has managed to compact and harden sufficiently.
During earthworks, to prepare a foundation pit for an extension, the properties of the soil may change, and this pit may violate or weaken the density of the soil under the old part of the house. Often this happens when the pit has been open for a long time, the earth in it has been exposed to rain, melt water or frost. The soil can have a loose structure, especially in freshly filled excavations, which affects the change in the outflow of rainwater. In most cases, these changes can only be revealed after the construction is completed.
Uneven subsidence of the foundation in any case entails deformation, while cracks and cracks form at the joints between the old and new parts of the building. When planning the construction of an extension, it is necessary to take into account these circumstances in the project documentation and strictly observe them. These problems do not arise during the execution of the extension if the house and the extension are separated with a sedimentary seam. As a rule, sedimentary seams are arranged 1-2 cm wide. It runs from the very bottom of the foundation to the highest point of the building: through windows, floors, pillars, walls, beams, ceilings, etc.
The slots are filled with elastic material: elastic tapes, polystyrene foam, plastic silicone, acrylic or bituminous masses. If the architect or planner had not provided for the sedimentary seams, then after some time (a couple of months) after the completion of construction, the plaster would begin to crack, floors, ceilings, and walls would burst. It also happens that the stress caused by subsidence is not able to withstand window panes, doorways. They can warp, jam when opened. In the cracks that appear, water can form, flooding the rooms under the bathroom, basements, cellars, etc.
In most cases, expansion joints are designed in such a way that they are visible at the separation of the facade. Usually, from the front side, this seam is sealed with a low-strength material, covered with platbands or false panels that do not prevent the building from settling and the mutual displacement of the outer walls. They can be hidden by installing drainpipes on the facade. On the roof, the expansion joint is covered with a special compensation device. Another problem is the lateral expansion (displacement) of the house.
In this case, it is necessary to qualitatively protect the old part of the house, since it is usually structurally weaker. In this case, it is necessary to design the attached part of the house in such a way that its foundation and load-bearing walls are perpendicular to the old part of the house. In this case, the outer walls of the old house will become the inner walls of the attached premises, and the expansion joint will be located at the junctions of the floors and walls with ceilings and the walls of the extension.
Another option for reliable protection of the old structure is the creation of a project for a new supporting structure. Soles and foundation tapes in this case must be placed at a safe distance. In some cases, the distance from old to new foundations can be several meters. In this case, the ceilings are mounted in such a way that they do not reach the old structure by the size of the sedimentary seam and do not rest on the walls of the old building.
In addition to the options considered, it is possible to connect structures in an atypical way. For example, floor slabs can be laid on two walls – a new one and an old one, but at the same time, a slight movement of the wall can be provided, which can be caused by uneven subsidence of the foundation. In some cases, architects and designers also use other, extraordinary solutions. Sometimes the old foundation is wide enough for a new wall to be built on its surface. In any case, do not forget about the protection of the junction (adjacency).
Before realizing your plan and building an extension, you need to carefully study the design and condition of the foundation of the old house, learn more about the quality and density of the soil, choose the right connection method, plan all stages of construction, and strictly adhere to our recommendations.