Quite often, owners of private houses want to increase the area of \u200b\u200btheir home by adding new premises. In this case, the primary issue is the choice of the foundation on which the additional structure should be located, because the reliability of not only the new extension, but also the main building depends on this. In addition, it is important to correctly coordinate and connect the new and old structures. Next, we will tell you more about how to make a foundation for an extension, taking into account all the technical characteristics of the building.
There are several types of foundation for an extension to the house:
- Reinforced concrete tape monolithic.
- Reinforced concrete tape prefabricated.
- Columnar.
- Pile-screw.
- Pile.
Considering all the options for the foundation for the house and an additional extension to it, most often they prefer a reinforced concrete tape monolithic or prefabricated type of basis. They are quite reliable, strong, durable. They can be easily connected to the main building without disturbing the structure of the supporting structure. Therefore, these types of bases are used mainly for massive and large outbuildings made of heavy materials, such as brick. As for the pile and pile-screw type of the base, they are recommended for lighter and simpler extensions, for example, for frame structures or for terraces, verandas adjacent to the house. It is worth saying that if you build an extension without a foundation, it can cause collapse and deformation of the entire structure.
Extension foundation bonding options
In addition to the type of foundation for the extension, you should choose the right options for linking it with the main house. Before performing these works, it is necessary to conduct a thorough analysis, including:
- The study of the characteristics of the type of soil on the site.
- Measurement of the level of passage of groundwater.
- Inspection of the state of the foundation of the main building (its technical characteristics and quality).
There are two options for connecting the old and new basis:
- Rigid connection with reinforcement. Such a pairing of two foundations is possible when the extension is being built on a non-heaving type of soil. On other types of soil, it is recommended to use other types of connection of bases. In addition, a reinforced connection is advisable when the foundation of the main building is already firmly “rooted”, its complete shrinkage has occurred and no further displacement is expected.
- Connection by forming an expansion joint. Such two foundations are simpler and easier than pairing according to the first method. This is useful in the case when a frame extension is being built.
The technology for mounting a rigid connection with reinforcement is as follows:
- First of all, you should analyze the soil (determine its type and depth of groundwater). Next, the type of foundation on which the main building is erected is determined. Usually, for massive brick buildings, a tape or columnar basis is used.
- To conduct a deep analysis of the characteristics of the foundation, you should dig a trench along its perimeter. The dimensions of the base can be measured using an iron bar, which is sunk into the ground to the same level as the old base. When the buried rod rests against the base of the foundation, a mark must be made on its upper part. Having taken out the iron rod, we measure the distance from its edge to the mark made. The resulting segment will be equal to the width of the installed bearing base.
- If it is determined that the soil on the site is not heaving, then the same type of basis should be erected as that of the main building, even if the new extension is framed or made of lightweight foam blocks.
- The new foundation is laid to the same depth as the old one. Further, holes for reinforcement are drilled in the old base. The diameter of the holes must match the dimensions of the iron bars.
- If it is not possible to pre-drill holes, then you can immediately hammer the reinforcement into the old foundation, in the same way as the anchor is hammered. Further, with the help of spacers, the reinforcement is attached to the base. It is necessary to correctly determine the required number of reinforcement bars, which will be required to fasten two bases. Usually 1 sq. m. foundation requires 5-6 rods. The fittings are cut into the required number of segments using a grinder.
- We fix the reinforcement bars in the old foundation. We attach strong metal washers to their edges by welding.
- Next, the protruding reinforcing bars during the construction of a new foundation are poured with concrete, so that they are inside the new structure.
The connection installation technology by forming an expansion joint is as follows:
- First of all, a new foundation should be erected, located next to the main building. Usually, in this case, the construction of reinforced bases is not required. However, the technical features of the main building should be taken into account. It may be necessary to strengthen the new basis.
- The gap between the old and new foundation should be no more than 4 cm. To get the right distance, before laying the new base, make wedges from wooden bars wrapped in plastic wrap. After building a new foundation, these wedges can not be taken out, but left inside the structure.
- If a new extension is being built on heaving soil, the level of its shrinkage should be taken into account. Depending on this, the height of the floor of the future structure is regulated.
- If a small extension of one or two floors is being built, then the distance between the old and new walls should be no more than 20 mm.
- The distance between the walls is filled with sealing material, for example, tow, mineral wool, polyethylene foam.
- Next, the gap should be properly sealed. To do this, use sealants that are resistant to precipitation.
- The resulting seam between the old and new building can be hidden with the help of decorated overlays. Usually decorative inserts are attached to the wall of the main house.
Technology for building a foundation for an extension
Characteristics of the strip foundation
A strip foundation is being erected for an extension to the house with their own hands in the event that an additional structure is built of brick. In addition, reinforced concrete monolithic structures will be relevant when the additional extension has a basement or basement. As mentioned above, heaving soils that can cause a large shrinkage of the building are not suitable for the construction of this type of basis. Best of all, such a base "feels" on dry and stable soils.
The scope of the strip foundation is quite extensive. It will be relevant in such cases:
- During the construction of houses made of brick, cinder block, concrete.
- For the construction of bath rooms.
- During the construction of capital garages.
- For the construction of outbuildings, summer kitchens, garden spaces.
Advantages of the strip foundation:
- Strength. Suitable for large massive structures.
- These types of foundations can be built independently without the involvement of specialists from construction companies.
- Long service life.
- You can build a foundation "for a different budget."
- For the construction does not require the use of large construction equipment.
Disadvantages of strip foundation:
- For the construction will require a large amount of building materials.
- Construction work is quite labor intensive.
- You can not build on heaving soils.
Strip foundation construction technology
The order of work is as follows:
- First of all, you should draw up drawings of the foundation for the extension. All dimensions and technological features of the future design are noted here. Based on the drawings made, marking is done. Check the correctness of the markup using the building level.
- Next, they begin to carry out land work - they dig a trench. In this case, the level of soil freezing should be taken into account. The foundation must be placed lower than this depth.
- Then you should equip a pillow of crushed stone and fine-grained sand at the bottom of the trench. The thickness of this layer should be about 150 mm.
- Next, you should think about how the foundation of the main building and the extension to it will be fastened. As mentioned above, there are two methods for pairing the old and new basis - a rigid connection and the arrangement of an expansion joint. If a rigid connection is chosen, then the basis of the additional structure should be reinforced with iron rods. The reinforcement cage is fastened with jumpers. Usually 4-5 iron bars of reinforcement are tied together.
- The next step is the arrangement of the formwork. It is necessary only for that half of the basis, which is located above the soil level.
- Next, you need to fill the foundation. To do this, calculations are carried out, how much concrete mixture will be required for these works. When calculating, the following indicators are taken into account: length, width and height of the base.
- The concrete mixture is prepared from fine sand, crushed stone, water and cement. In order for the solution to have the required consistency, a concrete mixer is used to stir it. If it is not possible to prepare the mixture with your own hands, then you can purchase ready-made packages of dry concrete at a hardware store.
- Concrete is poured in stages, in layers of 200 mm. After pouring each layer of the solution, it should be well tamped. For this, wooden rammers are used.
- After the concrete is poured to the fixed markup, the mortar layer is leveled with a trowel. Then, in certain places, the filled base should be pierced with reinforcement so that the remaining air comes out of the structure and it acquires a stronger shape.
The tape base hardens in about 25-30 days. At this time, the structure should be protected from the effects of weather conditions: in hot weather, the concrete base must be sprayed with water, and in cold and nighttime, it must be covered with waterproof material.
Foundation for frame extension
The foundation for the frame extension is being built in the following order:
- Concrete pillars should be installed in the main supporting parts of the structure. These supporting elements are placed in increments of 1 m. They deepen lower than the level of soil freezing.
- Next, a frame of reinforcement is installed and strapping is performed.
- Then a waterproofing layer is laid.
- Strengthen the structure by pouring concrete. Next, wooden bars are attached to the supporting elements.
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