Due to the speed of construction and affordable cost, frame houses are becoming popular in Russia. The durability of the building largely depends on the reliability of the foundation. When choosing a foundation, the expected load, the type of soil and the features of the relief of the site are taken into account.
Soil characteristics
Before developing a building project, it is necessary to conduct geological surveys and draw up a topographic plan of the area. Drilling a well or digging a hole allows you to study the soil. There are several main types of soil:
- Rocky, gravel and sandy soils are the best option for construction. They do not contain voids, are waterproof, and have a low compression ratio. Sandy soil of uniform density does not swell when frozen.
- Clay soil due to porosity in winter increases significantly in size. Frozen water causes swelling, creating pressure on the base of the house. Moisture affects the load-bearing capacity of the soil, with an increase in the parameter, the ability to withstand the load drops.
- Loam is a type of soil containing sand and clay in a proportion of 3-10% to 30%. Suitability for construction is inferior to sandstone, but better than clay.
- Peat, loess and quicksand are soil types characterized by uneven compression and low water resistance. Such soils are not suitable for the construction of buildings.
If there is weak soil in the purchased area, it is compacted or replaced. In the first case, they use tamping with surface vibrators, cementation. The second method is to remove the soil to a certain depth and replace it with a sand cushion.
Foundation requirements
When choosing a base, price is not a decisive factor. The main criteria are safety requirements, compliance with the type of soil and the technical features of a particular project.
General requirements for the foundation of the house are:
- Strength and resistance to movement and heaving of the soil, which provides the material of the structure.
- Durability - the foundation and construction must have the same lifespan.
- Profitability - the optimal cost of estimates is based on the purchase of materials of local production, the appropriateness of the selected type of design.
As a material, concrete, reinforced concrete is recommended, for sandy soil - brick and cinder block. With a low level of groundwater, the use of wood after antiseptic treatment is allowed.
Rules for choosing the basis
When choosing a foundation for a frame house, its design features and geological data of the site are taken into account. In order to prevent uneven subsidence, high humidity in the basement and other problems, it is necessary to choose a design that meets the following criteria:
- dimensions, weight, number of storeys and configuration of the building;
- groundwater depth;
- soil freezing level;
- seismic activity in the region;
- basement planning.
Groundwater level and freezing depth affect the choice of type of structure. For heaving soil with a high groundwater level, a fully buried strip foundation is recommended. The shallow structure is suitable for the area where groundwater is far away, and the soil freezes to a shallow depth. The slab as a base is used on moving or bulk soils. Piles as a building support are used for any soil.
The influence of the frame house on the foundation
Heavy brick buildings with reinforced concrete floors create a high load on the base. The budget for laying their foundation is 20-30% of the total construction budget. With lightweight frame buildings, the situation is different. Their weight is much less, therefore, the foundation can also have a lightweight design.
Knowing the technology of building a cottage, specialists make the calculation of the estimated load. This will require information about the type of frame (timber, logs or metal guides), insulation, exterior and interior decoration materials. The foundation for the frame and panel house can have a limited area of support on the ground. These types include pile and columnar structures.
Types of foundation for a frame house
Light buildings can be built on any basis, but most often the following types of construction are used:
- tape;
- pile;
- monolithic;
- columnar.
They have different stiffness and resistance to swelling of the soil. Detailed information on the pros and cons of designs will help you decide which foundation is better.
Tape
The foundation is a reinforced concrete strip around the perimeter of the entire building. Before pouring concrete, formwork is installed. Necessarily performed reinforcement with an iron bar. The design is of two types:
- Shallow tape - it is laid in a trench 40-60 cm, it protrudes 30-40 cm above the ground. For reliability, a continuous reinforcing belt is arranged. The base is built on a sand cushion.
- Deep laying - the structure is located below the level of soil freezing. The exact value is taken from the region reference. The base has a high bearing capacity.
Advantages:
- There is the possibility of a basement
- high reliability and durability;
- simplicity of the device.
Disadvantages:
- increased consumption of material (for a fully buried base);
- long production period (it is required to wait for the concrete to dry);
- not suitable for areas with high groundwater levels.
Concrete tape is suitable for heavy houses, in private construction this is the most common version of the foundation.
Pile
During construction, piles are used in areas with heaving unstable soil. Supports are of several types: stuffed, jellied, screw. Ready-made piles are twisted or driven into the ground, printed piles are made directly on the site. In the construction of light houses, metal screw piles are popular. They can be screwed into the ground on their own. To connect the supports in a common design, a grillage is mounted on them.
Advantages:
- erected faster than other types of foundation;
- suitable for all types of soil;
- earthwork is not required.
Disadvantages:
- significant heat loss;
- metal piles are subject to corrosion.
Monolithic plate
A slab foundation for a frame house is a type of monolithic base used on soils with high compression. The base is made of concrete and reinforcement, located under the entire building. Under the plate, a pillow of sand and gravel is poured, insulation and waterproofing are laid. The base is flat or with additional stiffeners.
Advantages:
- provides stability of the house on heaving soils;
- can be used with close occurrence of groundwater;
- long service life;
- universality, used in standard projects of country houses.
The disadvantage is the high cost due to the high consumption of materials.
Columnar
For small houses, a columnar base is used. Supports are concrete, stone or brick. They are installed in the corners of the building, at the intersection of the walls, in areas of increased load.The distance between the pillars is 1.2-2.5 m. The lower part of the supports is in the ground, and the upper protrudes 50-60 cm above it. A beam of beams is laid over the posts.
Advantages:
- differs in the least financial expenses;
- can be done independently;
- quickly erected.
When building on heaving soil, a columnar foundation reduces the life of the building. In addition, there will be no opportunity to make a basement.
Warming and waterproofing
For insulation and protection against moisture, materials resistant to environmental influences are selected. The strength and durability of the structure depend on the quality of the waterproofing. Two types of materials are used:
- liquid mastic;
- rolled waterproofing.
Bitumen mastic is the most affordable option to protect a concrete surface from moisture. It is applied to a clean and primed base in 3-4 layers. The composition penetrates into the pores, fills the cracks, prevents the spread of mold. After drying, the mastic is covered with fiberglass or insulation is installed. Another material for waterproofing is a bitumen-polymer emulsion or liquid rubber. It forms an elastic, monolithic and durable coating. The lack of material is the high cost.
Cloths of rolled insulation serve as the main or additional protection of the concrete structure. For gluing, roofing material or modern materials based on fiberglass (Isoelast, Tekhnoelast) is used. The material is glued to hot mastic. The sheets of roofing material are laid with an overlap of up to 15 cm, the joints are soldered with a gas burner.
Instructions for insulation
Thermal insulation of the foundation occurs at the construction stage. Plate, sprayed or bulk materials are used. Synthetic heaters penopleks and expanded polystyrene do not decay, perfectly retain heat, are resistant to moisture. The thickness of the insulating layer for them is about 100 mm. The insulation is installed after waterproofing. Plates are mounted on special glue and dowels, fungi. Outside plastered on fiberglass.
The sprayed polyurethane foam is characterized by low thermal conductivity and the absence of cold bridges. This is an effective insulation, forming a monolithic waterproof layer. It has adhesion to any surface. The only negative option is the payment for the work of spraying specialists.
Thermal insulation of the base of the frame house can be done with gravel or expanded clay. Work begins with digging a trench around the perimeter of the structure and the drainage device. Fill insulation loses its properties when wet, so moisture must be removed. Geotextiles, special pipes are put in the drainage ditch and they are covered with rubble from above. The expanded clay trench is waterproofed with polyethylene. For effective insulation, its width should be at least 60 cm. A blind area is arranged on top of the bulk material.
