Sooner or later, in almost any household, there is a need for additional living and working space. When planning the construction of new buildings by joining the existing main house, it is important to take into account all the loads and the impact of the inevitable shrinkage on both parts of the structure. Before starting the construction of any such structure, it is necessary to equip the foundation for the extension. In case of errors during construction, deviation and distortion of the structure is possible. That is why the most important stage of the process will be the design and installation of the foundation for the future premises.
We must not forget that the implementation of any major projects requires coordination with regulatory organizations. To build an extension to an existing building is a rather responsible task, as well as the construction of a full-fledged house. An accurate calculation and a well-planned action plan are required. A number of professional tools are involved. Most likely, you will have to get helpers. And yet, subject to the technological process, it is possible to do it yourself, without involving third-party specialists.
Preliminary work
In order to determine the type and dimensions of the base of the building, a pit 100 × 150 cm or 100 × 100 cm breaks out near any wall. The strip foundation is measured in width and height. For a columnar, the parameters of the pillars and the depth of their laying are important. Enough attention should be paid to this issue, since marking the foundation is one of the most important stages.
The size of the base is measured using a steel rod, the end of which is bent 90°. The rod is placed under the sole, placing the bent part strictly horizontally. By turning it, they detect the moment when the curved edge rests against the wall from the inside, a mark is placed on the metal. The distance from the bend to the mark, measured after the rod is removed, will correspond to the width of the tape.
At the time of development of the pit, the type of soil on the site is also determined. From the data obtained will depend on which foundation to choose.
If a project of an old house is available, preliminary measurements are not required. But it is necessary to know the geological characteristics. Careful planning at the initial stage of work, taking into account all the features of the area, will help to avoid mistakes.
After the analysis, you should decide what design the future foundation should have. There are several types of them:
- columnar;
- tape reinforced concrete;
- pile and pile-screw.
With rare exceptions, the extension has the same type of foundation as the house. This ensures the reliability of the entire structure.
Foundation Rules
- In the process of attaching two bases, it is impossible to dig the entire perimeter at the same time if it is more than 3 meters. This will make the building less stable.
- When the building is located on a concrete slab, another slab is poured nearby. Similar ones are attached to a pile, strip or column foundation. The difference in characteristics will create an excessively large stress on the existing foundation, which will lead to greater shrinkage, and sometimes the collapse of the entire structure.
- The depth of the foundation for the extension must be planned somewhat less than for the main building. This creates a place for future shrinkage.
- Further work is carried out only after shrinkage of the poured concrete. It usually takes about six months.
- Coupling can be done in the following ways:
- Separate installation and subsequent formation of an expansion joint;
- Rigid bond with common reinforcement laying.
To correctly fill the foundation for an extension, you need an error-free calculation. The choice of communication method depends on the type of land in the area. This is also affected by the dimensions of the attached structure.
Hard connection
This method is used in the following cases:
- on non-rocky and slightly heaving soils;
- if there is a shallow strip foundation, the basement of which forms a single whole with it;
- when the shrinkage of the building is predictable;
- when summing up an extension of several floors under one roof with the main house.
In the case of the columnar version, the reinforcement is mounted on the plinth, if it has sufficient dimensions. When the length is not enough, it is more logical to choose another method. Violation of this rule is fraught with cracks and unsteadiness.
How to start connecting tape samples:
- A ditch is cut out to the desired size. A layer of sand is poured to the bottom to ensure stability.
- Holes are drilled in the foundation. Each next row is drilled with an offset relative to the previous one.
- Metal rods are driven into the holes with a longitudinal slot at the end, into which wedging wooden liners are inserted.
- With the help of protruding pieces of reinforcement, a foundation is formed for the extension.
- After the frame is ready, concrete is poured.
- Further work can only be continued after the structure shrinks. This standard is observed for any filling options.
The slab foundation is connected in this way only if its thickness is more than 400 mm. The possibility is preserved even when the slab protrudes beyond the basement of the house. The protrusion must be more than 300 mm. The fittings are exposed and welded to the metal frame of the base of the extension. Such protrusions are often found in buildings made of foam blocks.
Separate erection
When working with a tape base, the territory is marked out and a ditch about 600 mm deep is dug under the tape. The bottom of the trench is covered with sand or gravel to create a cushion. The next step is to install a solid formwork according to the given dimensions. Reinforcement is made with metal rods and cement mortar is poured. A free-standing foundation for an extension to the house guarantees durability and stability of the result.
When using this method, a void is left between the wall of the old house and the foundation of the extension. The width varies from 100 to 150 mm. Inside, a layer of waterproofing and thermal insulation is laid. It is imperative not to miss this moment and make such a deformation seam that prevents shrinkage and protects against damage. The new sole is slightly higher than the old one. Over time, it will settle to the same depth as the main structure. This will ensure the reliability and durability of the entire structure.
In addition to the strip foundation, a columnar foundation is also used, closely adjacent to the main building. Piles are preliminarily waterproofed and installed on concrete pads. Next, the strapping of the required dimensions is mounted. This method reduces construction time, allowing construction to continue in just a few days.
Frame extension
The foundation for the frame extension does not carry significant loads. Basically, such designs involve the use of lightweight materials. In this case, the correct solution would be to use a columnar view.
The work takes place in several steps:
- holes are dug in the ground below the freezing level;
- the bottom is covered with sand and gravel;
- fittings are installed;
- work on the installation of formwork;
- cement mortar is laid;
- pillars can be supplemented with brickwork.
It is possible to make an extension to the house using a variety on screw piles. They are screwed into the soil and cut off to the desired height. In order to increase strength and durability, concrete is poured, then the heads are welded.
This type is characterized by speed of execution. After its installation, it is possible to proceed to the construction of a structure from timber, OSB or plywood. The finished structure cannot be further weighted with any elements. The whole process should strive for minimalism.
If the house is made of brick or wood
In this case, tape variations of reinforced concrete are used. The basis for an extension attached to a brick house is installed in the following order:
- The territory is marked according to the developed plan.
- Trenches are dug below the freezing level of the soil.
- The bottom is covered with a sand-gravel mixture to a height of 100-150 mm.
- A rigid binding to the existing base is established and an expansion joint, if necessary.
- The foundation for the extension is reinforced with a reinforcement frame. Most often this is a design of four segments with jumpers.
- Formwork is exposed.
- The concrete solution is poured.
In the same way, the foundation for an extension to a wooden house is also made.
The best option for building an extension is the one in which it is built together with the main building. Unfortunately, it doesn't always work out that way. The need for expansion may arise due to family circumstances, hobbies of the owners of the house, and also depends on financial issues. It is quite possible to attach a room to the house on your own, if you follow all the rules and recommendations.
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