Technology of bored Foundation
The contents
- What is a Foundation?
- What are its advantages and disadvantages?
- Types of raft Foundation and its implementation
Bored Foundation of today can be called one of the most common among all the existing types, and this is not surprising, because its use differs important advantage – versatility. It is possible to build even on the most difficult terrain, while providing maximum preservation of the integrity of the Foundation, as the most reasonable and optimal for today variant in the process of construction of the building is pile Foundation, which is ideal as a base for houses of brick and aerated concrete.
To sustain the Foundation is not even the largest mansion may not every area, therefore in the construction process will need to resort to various tricks, especially when it comes to the construction of country houses.
What is a Foundation? ↑
The raft comes from the German word Rostwerk, that is, structure-lattice. The design is a combination of a large number of piles in one piece.
As a Foundation grillage plays a very important role, because through its use all the loads that will be building on the piles are distributed evenly. In this case, the grid can be represented not only as some beams, but also to be a full concrete slab.
Bored piles Foundation technology which will be discussed later, plays also another important role – through piles with a raft Foundation the load is transferred from the entire surface of the building to the ground. If we are talking about wooden houses, such role is played by a lower crown design, but we’ll consider it brick built.
What are its advantages and disadvantages? ↑
First and foremost, you should consider the positive side, which is different on bored pile Foundation:
- the construction process is no different a loud noise, so work can be carried out around the clock even if they are held in close proximity to other residential buildings;
- with the introduction of the pile into the ground, there is a very slight vibration, therefore entirely eliminating the possibility of damage or deformation of nearby buildings, if you are tight urban infill development;
- the technology of continuous auger during the drilling process does not provide for the extraction of significant ground masses;
- the Foundation of bored piles involves changing the depth and length at different levels, if we are talking about building houses on the side soils.
- unlike a normal factory, bored piles can be used in any diameter, there is no need of the original procurement, transportation and subsequent storage of the whole set of such products;
- there is no need to buy or rent high-power pile-driving machine;
- there is the possibility of adjusting certain structural features of the piles, including the lack of reinforcement in the lower part;
- relatively low cost and short construction time of a brick house.
But there are certain disadvantages:
- metal piles are subject to corrosion;
- the Foundation cannot be used on rocky soil;
- for the construction of the basement will need to carry out certain additional works, and use additional material that is related to financial costs;
- the use of this Foundation quite difficult if the house is built on the gravelly soil.
Types of raft Foundation and its implementation ↑
Bored Foundation with raft Foundation under the brick house in the majority of cases is executed in the form of a tape or plate. If slab raft Foundation will fully combine between the end walls of each pile, then the tape will merge only those piles that are in close proximity to each other, and are located directly under building walls.
Modern experts in order to build the Foundation piles with a grillage using a variety of materials including wood, steel and monolithic and precast reinforced concrete, but the use of metal is not recommended, for the reason that it will have to spend in large numbers.
In order to equip the metal grillage, you will need to use a specialized crane, and to apply corrosion-resistant coating. That is why the most technologically effective and practical option for modern experts call the construction of monolithic grillage made of reinforced concrete.
Drilled Foundation is the most common ↑
In addition to that piles in principle are a relatively inexpensive material, providing a significant Foundation strengthening, they are also very large bearing capacity. In the majority of cases, well made pile can withstand loads of about 1600 kg, and for maximum strengthening of the Foundation of the house will be sufficient to use approximately 30 to 50 piles.
Are bored piles with a raft Foundation below the level of soil freezing, it is worth noting the fact that after installation they necessarily need to sign a shirt, that is covered with two layers of roofing material. Use this shirt will allow you to significantly reduce the pressure on piles at low temperature, when they begin to be ejected outward and will provide good waterproofing.
As the Foundation is being built with raft? ↑
In fact, if work is carried out competently and skillful expert, then you are guaranteed to receive quality work, regardless of what time of year they are held. Build it like this:
- formwork is installed on top of piles;
- the frame is mounted directly inside the formworks;
- the raft is carefully filled with concrete. It should be noted that in this case uses exactly the same technology as in the case with strip foundations;
- height of grillage ideally is approximately 30 cm, the width of the design should be much more in comparison with the thickness of the walls of the building that is to be at least 40 cm.
In this case it is important to note the fact that for the construction of foundations on bored piles will not need to spend a large amount of earthworks, and to give a large amount of time and money. If you’ve just opted for this method of construction, then eventually you will get very reliable and solid ground, which will fully meet modern requirements.
The types of combined piled-raft Foundation ↑
There are two main varieties the Foundation of this type:
- hanging with a grillage;
- with the recessed grillage.
In the majority of cases with a suspended grillage Foundation is used in case if we are talking about the construction of light timber-framed houses, but in some situations, its use is also in the construction of heavy houses, with even more powerful designs.
The use of Foundation piles with embedded raft is recommended for those wooden houses, the walls of which are made of boards of a thickness up to 300 mm. However, the use of this option will be relevant in the presence of the construction of bored pile Foundation under the house from a brick or any monolithic construction.
Features of construction of the Foundation under the house of bricks ↑
Unlike buildings made of aerated concrete brick house is more difficult. Pile Foundation for a brick house provides a large enough diameter and depth of piles, and these parameters must be define at the design stage. In this case, it is essential to be properly reinforced raft Foundation, and also the interface of it with the piles.
Overlaps such a Foundation, in most cases the floor slab, and any areas of increased complexity are executed as monolithic. It should be noted that the sole of the grillage will not be considered as bearing element of the Foundation, and its reliance on the soil occurs only in the case when the weight of the building can balance the swelling soil.
Pile Foundation with raft Foundation represents the most optimum choice for serious homes, and thus it is the most economical among all the varieties of foundations available today.
Learn more about the features of drilled Foundation you can find on the video: