If you consistently follow all the recommendations that will be given in this article, then almost any owner will be able to build a foundation for an extension on their own. Moreover, if you do it yourself, then the cost of construction will be significantly lower than that of workers hired by ad. The ideal option can be considered if the key points of how the main construction was carried out and if there is a project with geodetic survey data remained in the memory. All this will greatly facilitate and speed up the construction of the foundation.
Linking the main and attached foundations
When hatching the idea of an additional extension to your main house, you should understand that it cannot be just taken and stuck. Any construction activity must be carried out consciously and after strict calculations. Otherwise, you can damage the existing housing. After all, the new extension will have an impact on the ground, which can begin to move, which will cause damage to the structure. Therefore, when building an extension, it is necessary to connect its foundation with the foundation of an already standing house.
The foundation can be attached in several ways:
- rigid connection, this method should be used in those houses that have been built for a long time and their foundation has already been established. In addition, with the help of simple calculations, you should make sure that the load that has arisen will not bring deformation of the old foundation;
- arrangement of special expansion joints.
A slight retreat, a rigid connection should under no circumstances be practiced in places where non-rocky soils exist.
Let's consider in more detail each of the ways to arrange a new foundation for an extension to a wooden house.
Rigid Foundation Combination System
Before you start pouring the foundation for the extension, you should remember on what type of foundation the house was built. We most often use tape or columnar types of foundation, less often you can find a foundation based on slabs or piles.
In addition to the type of foundation, several more factors should be determined that may affect future construction, namely:
- the depth to which the foundation is laid;
- determine the space that he occupies under the house;
- identify the types and types of building materials that were used in the construction of the foundation.
There will be no particular tragedy if some of the information is lost, it can be restored as a result of new research. For this, a special ditch is dug along the old foundation, which gives an idea of the size of the foundation. Its depth is determined using a simple tool, a piece of reinforcement, with an end like a poker. This end should be pushed under the base so that it literally lies under it.
After that, the reinforcement should be turned to a horizontal position and stretched to the stop of the rear wall, after which a notch should be made in the place where the wall ends. We remove the probe and repeat the operation along the entire wall, this will allow us to get a fairly accurate picture of the dimensions of the foundation.
The new foundation must be built exactly the same type as the old one. Moreover, this should be done after calculating the heaving of the soil at the construction site. Calculations must be done in any case, there should be no excuses that I am building a small extension, or it will be made of lightweight materials. In addition, the new foundation should not lie deeper than the old one, they should be located on the same level.
At the next stage of construction, we will need to drill holes for reinforcing reinforcement. The holes for it should be slightly larger than the diameter of the rods themselves. Inexperienced builders often have a question: to what depth should reinforcement be deepened? To calculate it, there is a universal formula: the recess should be 35 rod diameters.
There are cases when the width of the base of the house is not enough to drill holes of the desired depth. In this case, proceed as follows: vertical slots are made at the end of the plate, into which special wedges are inserted. This system is called anchoring, with its help the new foundation will receive a strong bond with the old one.
It is very important to correctly calculate the required number of reinforcing bars. This will envy the strength of the entire structure, if an insufficient number of them are installed, then the foundation will be weak, if more than the technology requires, then this is a waste of money. As a rule, they are installed at the rate of 5 pieces per quarter meter. The required length of the rods can be cut with a grinder, or you can order ready-made ones. To enhance the effect of the installed rods, small pieces of metal or nuts can be welded onto their free end. These ends will be filled with concrete, as a result of which the structure will receive additional reinforcement.
Proper arrangement of thermal seams
The thermal seam avoids the negative effects of seasonal and daily temperature fluctuations. To obtain a so-called expansion joint, when pouring a new foundation, a small gap should be left (2 cm for small buildings and 5 cm for buildings more than one floor high) between the new and old foundations. A board of the required thickness wrapped in plastic wrap and placed between two bases will help to get the right and even seam.
Digging a trench and pouring the future foundation
Before starting to dig trenches for the future base, it is necessary to clearly determine where it will be located and mark its boundaries. This will greatly facilitate the implementation of all future work. For a more visual marking, you can use pegs and a skein of twine. The diagonals that are laid at the corners of the trench will make it possible to understand how correct the future foundation will be. With the help of a plumb line, you can get even and regular walls, because this is also an important factor that affects the strength and quality of the future structure.
If the extension is small, then the trench can be dug on your own, otherwise it is better to use the services of special equipment. After a hole of the required size has been dug, it is necessary to carry out primary insulation in it, pour a pillow of sand and gravel. Then you should think over all the necessary connections and communications, and you can start pouring the foundation.
In the manufacture of concrete, several mandatory rules must be followed:
- choose frost-resistant cement for the foundation;
- strictly observe the sequence of adding concrete components: water, crushed stone, fine sand, and only then cement;
- ready-made concrete should be quickly delivered to the place of work, it quickly hardens and becomes unsuitable for pouring;
- put the formwork only after filling the trench with concrete, remove it no earlier than a week after pouring;
- Before building an extension, waterproofing must be laid on the foundation.
Subject to all these conditions, it will be possible to quite successfully, by one's own efforts, obtain a quality foundation for the future extension of one's own wooden house. At the same time, the cost of the construction itself will cost you at the price of building materials and rented tools.
Video - the foundation for an extension to a wooden house
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