There are several types of foundation foundations, but among the most common and used are pile and tape. They differ significantly in design, but serve one purpose - to ensure the stability of the building and to avoid subsidence under the weight of building structures. But what is better - strip or pile foundation? We analyze further in the text of the article.
Description of the bases on stilts
According to the constructive solution, piles are strong columns, hammered, screwed or inserted into the ground and resting on dense layers of soil below the freezing point. In the upper part, all the column heads are interconnected by a horizontal grillage, which serves to evenly distribute the weight load from the walls between them.
According to the installation method and execution, there are three main types of piles:
- clogged;
- screw;
- bored.
They can be made from:
- tree trunks;
- metal rolling;
- not reinforced concrete;
- prefabricated reinforced concrete.
It should be said right away that today piles of wood are used very rarely and only for temporary structures, the operation of which is designed for no more than 2-3 years.
Driven piles. Supports of this type are prefabricated from reinforced concrete and driven into the ground using special construction equipment (more on this can be found here). The technology of driven piles is used in multi-storey construction and in the construction of massive large buildings in private.
In most cases, a shallow foundation is used as a grillage. Hammered reinforced concrete supports are characterized by a high level of reliability, but require the highest costs associated with the high cost of materials and the use of special equipment.
Screw piles. Are made of steel pipe metal rolling. They are a steel pipe construction with a pointed end above which helical blades are welded. Screw supports can be used on all types of soil, except for boggy peatlands and with a high content of stone.
They can be installed manually or mechanically. As a grillage, steel is used in the form of a channel, an I-beam or profiled pipes. A grillage made of reinforced concrete or in the form of a shallow tape is allowed.
Bored bearings. To install a pile foundation of this type, wells of a calculated diameter are dug to the depth of freezing of the soil. A sand-gravel pillow is poured into them and a hollow formwork of pipes or rolled sheet material is installed. A reinforcing frame is mounted inside the structure and the concrete mixture is poured. After hardening concrete, the upper part of the supports is connected by a concrete grillage.
Due to the increased bearing capacity, bored supports are widely used for the construction of one and two-story stone buildings in private construction. Excellent structural stability allows construction on any type of soil.
Description of tape type foundations
They are massive building structures made of reinforced concrete, blocks, stone or brick. By the external configuration, such a foundation is a continuous support for the walls in the form of a flat tape. The use of a large number of materials makes the construction of a tape base a laborious and expensive event.
All the weight load from the building structures of the building is transferred to the stone strip and evenly distributed on the ground.
On stable dense soils it can be used for any buildings up to 5 floors high. With weak soil, the presence of heaving and horizontal movements, the maximum height of the house is up to 2 floors.
It is not recommended for use on wet and clay soils.
The construction of the strip foundation requires the organization and conduct of large volumes of earthwork. However, if there are basements or a large cellar, these efforts will be justified. Unlike pile foundations, the tape requires the installation of a sand and gravel pillow, the installation of formwork and the installation of reinforcing frames.
Advantages and disadvantages of pile foundations
To prepare a comparison base on what is better, a strip foundation or screw piles, it is necessary, first, to determine the advantages and weaknesses of pile supports. Pros:
- the cost is 25-30% lower than that of tape structures;
- quick terms for the erection of the supporting structure;
- the possibility of construction on most types of soil;
- high level of stability and durability;
- lack of earthwork and the use of bulk non-metallic materials;
- performance of work at any time of the year, even at low temperatures;
- ability to withstand heavy loads.
Despite the large number of positive qualities of the pile foundation, these structures have several disadvantages:
- the impossibility of installing piles in rocky and rocky soils;
- lack of basements under the building on a pile foundation;
- the need for insulation of the free space under the floor of the basement wall.
If you do not know the requirements for the manufacture of piles, you can choose and buy low-quality material. For example, metal screw products with a thin pipe wall, poorly welded blades or a structure that does not meet your soil type. Therefore, it is better to entrust the acquisition of material to a specialist who will carry out installation work.
Pros and cons of strip foundations
The main advantage of the strip foundation is the possibility of arranging basements and high-quality insulation of the lower part of the building. In the basement or basement, you can lay utilities, make a non-freezing water supply and organize several utility rooms.
Despite the large volumes of excavation and installation work, the construction of the foundation in the form of a tape can be done independently by inviting 2-3 assistants for this. Of the special construction mechanisms, you only need a concrete mixer and a vibrating device for compacting concrete. You can simply hire an excavator to dig a pit.
A correctly made strip foundation is durable and can last up to 150 years, despite any external negative influences. A layer of hydraulic insulation will protect the building from groundwater and meltwater, and thermal insulation will reduce heat loss.
At the same time, despite the listed number of advantages, the tape-type bases have several significant disadvantages, among which:
- large labor costs in the production of work at all stages;
- a lengthy construction process associated with large volumes of excavation and concrete hardening (we described the technology here);
- high cost of construction;
- the impossibility of construction on some types of soil;
- the need for process continuity when pouring concrete.
But if you take into account the feedback from developers, then the listed disadvantages are fully justified by the high level of reliability of the design and the presence of a basement.
Comparison of two foundations
Which foundation is better, tape or pile screw? To be honest, the strip foundations are used in the construction of buildings as a traditional structure, which has shown good results for a long time.
However, practice shows that pile supports have a higher bearing capacity. Let's try to compare these two designs by indicators such as:
- financial expenses;
- construction time and labor costs during the construction;
- possibility of use;
- manufacturability and seasonality.
Financial expenses
What foundation is cheaper than tape or pile? During the construction of the strip base there are expenses that are not required for pile structures:
- excavation and planning, storage and removal;
- transportation costs for the delivery of equipment, fittings and concrete mix;
- backfilling of sand and gravel cushion and its compaction;
- concreting or installation of blocks using lifting equipment.
Total strip foundation is much more expensive.
Construction time and labor
The design of the strip foundation is much more complicated in its structure. When it is erected, it will take time to carry out excavation work, install formwork and reinforcing cage, lay a pillow, pour concrete. After this, you will have to wait until the concrete mixture grasps properly, and begin waterproofing work.
In a pile foundation, it is enough to screw, hammer or install piles and tie them with a grillage. Work is performed several times faster.
Applicability
For pile foundations, there are practically no restrictions on use depending on the type of soil. An exception is swamped peatlands, on which usually no one builds anything. But the use of tape depends on the depth of its laying.
If the sole of the structure rests on dense layers of soil below the freezing point, then only lateral loads act on the tape and its stability depends on the degree of reinforcement, that is, the strength of reinforced concrete. Shallow foundations can only be used on stable, dense soil with a small freezing depth and deep groundwater table.
In the presence of a complex relief of the site, with a slope or elevation, the cost of the strip foundation increases sharply, while the pile foundation allows you to solve the problem without any problems.
Finally
As you can see, a comparison of the tape and pile-grillage foundations for technical and operational qualities gives a clear preference to the second type. However, if you decide to build a house with a full basement, and not a cellar, then only the tape structure allows this. In addition, when choosing a foundation structure, the type of soil at the building site plays a crucial role.