To properly make the foundation, you need to carefully study the options for the types of construction and their features. The construction of the underground part is carried out taking into account the following requirements:
- economic expediency;
- reliability;
- strength;
- durability;
- sustainability.
Before you begin construction work, you should conduct a study of the soil. The choice of the right type of foundation is influenced by the total weight of the house, strength characteristics of the soil and the level of groundwater. Carefully made and built in compliance with the technology foundation will last a long time and will not cause problems during operation.
Preparatory stage
It’s worth starting with pits or drilling. The main goal during this event is to find out what kind of soil is located on the site, as well as to find out the level of groundwater occurrence. It is necessary to lay the foundation in compliance with the rule: the level of the sole should be at least 50 cm above the level of the water horizon.
How to do soil research? Two methods are used for this:
- fragment of pits (deep pits, dimensions in the plan are usually 1x2 m);
- manual drilling.
In the first case, consider the soil on the walls of the pit. They also check if water has come from the bottom. In the second embodiment, the soil is examined on the tool blades.
After you determine what soil is available on the site, you will need to find its strength indicators. This can be done using special tables.
The cost of laying the foundation for a house can be up to 30% of the estimate for the entire building. To avoid cost overruns, you need to perform a calculation that will allow you to find the optimal design parameters that will simultaneously guarantee the lowest cost, strength and reliability. For your convenience, you can use the online calculation.
Types of foundations
DIY construction of the foundation involves the use of several technologies:
- Pillars
- piles
- tape;
- plate;
- combined options.
Columnar supports are characterized by low bearing capacity. Perhaps the device of monolithic pillars or their assembly of compact concrete blocks. Both options are great for doing the job yourself.
Pile foundation for the house is of three types:
- driven (not recommended for private buildings because of the need to attract equipment);
- bored (suitable for the construction of a brick or concrete house);
- screw (ideal for light wooden buildings).
Piles reduce the amount of excavation work. There is no need to dig trenches or a foundation pit, to take out a large amount of soil outside the site. Due to this quality, a device of this type of foundation is a very economical choice. The main disadvantage will be the inability to equip a basement or underground for utilities. The base of the building in this case is closed with decorative materials.
Another advantage of piles is the ability to use in a boggy area. Even if the groundwater level is close to the surface of the earth, the supports provide the necessary bearing capacity.
The next option is the tape. It can be made monolithic or from blocks. The second option is rational to use for mass construction. The strip foundation is:
- buried (for buildings with a basement, brick and concrete structures);
- shallow (for wooden and frame houses);
- shallow (technology of pouring the foundation for small buildings on a solid foundation).
Before making the tape, it is worth checking the level of groundwater and observing the rule that the sole cannot be closer than 50 cm to the groundwater horizon. Otherwise, there is a high probability of flooding the basement, reducing the bearing capacity of the base and the destruction of the materials of the supporting part of the building.
What to do with high GWL? If the structure is made independently of brick or stone, screw piles will not work, and for bored ones it will be necessary to lower the water. An excellent option is to fill the slab foundation. In this case, a shallow or slightly buried base is made. The thickness of the plate is assigned depending on the load, an average of 300-400 mm.
How to fill the foundation under the house
A monolithic type of foundation is the best option for private housing construction. In this case, installation allows you to significantly save on transportation and installation of structures. No need to hire a crane to install the elements in the design position or KamAZ for transportation of concrete blocks and slabs.
Monolithic foundations can be made from prefabricated concrete or mix the mortar yourself with a concrete mixer. The first option is recommended. The fact is that it is very difficult to strictly observe the proportions of the composition in artisanal conditions. For factory concrete, such a guarantor will be a passport, which indicates the verified performance of the material.
To make the material yourself, you will need to prepare clean water, cement, sand and gravel (or gravel). They are mixed with each other strictly observing the proportions, which depend on what brand of concrete you need to get. If you add a little more sand or gravel to the composition than is required, the strength of the supporting part of the building will suffer.
To properly fill the foundation, you need to familiarize yourself with the basic rules of concreting:
- Concrete should be poured in one go with time intervals of up to 1.5 hours. If you take long breaks in work, the mortar sets and concreting seams are formed, which weaken the structure. The technology allows you to make horizontal seams in case of emergency. It is unacceptable to arrange a monolithic foundation vertical seams, since in this case the support of the house will not be able to resist soil deformation.
- The class of concrete is selected depending on the type of support part. For a columnar or pile foundation, class B 15 is enough. For a tape, grades from B 15 to B 22.5 are needed. Building the foundation of a house using slab technology requires concrete of grades B 22.5 or B 25.
- After pouring, the material should gain strength. On average, it takes 28 days. It is possible to continue construction work after a set of 70% brand strength has been set.
- It is better to perform work in warm, dry weather. The ideal average daily temperature for hardening concrete is + 25 ° С. At temperatures below + 5 ° С, the material practically does not freeze. In this case, special additives and heating are used for normal hardening.
- Within 1-2 weeks after pouring, care must be taken for concrete. It consists in wetting the surface with water.
- For self-mixing the mixture you will need cement, sand, gravel (gravel) and clean water. The proportions depend on the strength class. Material is delivered from the factory by a concrete mixer - it allows you to extend the life of the solution and deliver it over relatively long distances.
How to fill the foundation? In general, the work is performed in the following order:
- installation of formwork and reinforcing cage;
- laying waterproofing material in the formwork;
- pouring concrete;
- its compaction by vibration or bayonet;
- curing;
- stripping works (if necessary).
For fast work with a concrete mixer, it is recommended to order a concrete pump. This technique is usually ready to provide concrete manufacturers. In this case, it is required to use a concrete mixture of grades P3 or P4 for mobility. Otherwise, the technique breaks.
Step-by-step instructions for filling the strip foundation
Concreting is considered on the example of a monolithic tape. To announce the supporting part of the structure, it is necessary to mark the construction site. For this, a cast-off and a construction cord are used. It is necessary to show the edges of the tape.
After marking, soil development is performed. In the absence of a basement, it is enough to dig a trench. At its bottom you need to make a sand pillow. It performs several functions:
- soil leveling;
- prevention of frost heaving;
The next step is the installation of formwork. In this quality, the material included in the estimate is used: boards (removable type) or expanded polystyrene (non-removable). The second option performs the function of not only the mold for pouring concrete, but also the insulation of the underground part of the building. When installing the formwork, I raise the base to the desired height.
Then mount the reinforcing cages. In the tape type, the working rods are arranged horizontally. They perceive bending loads. Read more about this in the article “Reinforcement of strip foundations“.
When ordering concrete from the factory on time, it is necessary to provide a convenient access to the construction site. Otherwise, the equipment will not be able to get to the site.
It will take a few people to fill. After laying the mixture, it must be compacted. This can be done with deep vibrators or a conventional reinforcement bar (bayonet). The task is to remove air bubbles, which after solidification will become the weak point of the structure. Cracks may appear here.
The first stage of concrete care is to retain moisture in it. If the material dries too quickly, surface cracks will appear. The structure must be covered with burlap or polyethylene. Every few hours it is moistened with clean water. This continues for a week.
Do not assume that pouring concrete is only for professionals. But one cannot be careless about this process.