In the world in almost any country you can meet a house on stilts. In some places, for centuries, housing has been built on wooden logs dug vertically into the ground. This technology allows you to build housing even on the water. In recent decades, nobody has been surprised by a house on stilts made of concrete. In modern construction, a real revolution took place after screw piles were used for the construction of light buildings.
General information
A stilt house is an ideal solution to the problem of construction where the soil does not fit a monolithic strip foundation. It can be built on sites with the following features:
• with previously created landscape;
• with difficult terrain;
• with increased soil moisture;
• where it is impossible to carry out earthwork;
• in areas with deep freezing.
The construction of houses on stilts is very popular today, but metal poles are especially demanded, which make it possible to quickly build small buildings with their own hands. The advantages of such buildings are:
• saving time and cost of construction;
• the ability to carry out work on problematic soils;
• lack of need for soil leveling;
• the possibility of erecting wooden structures on lawns, slopes, near trees;
• high piles protect the house from the penetration of rodents;
• during floods, the house is protected from possible flooding;
• the use of high piles makes it possible to use the area located under the house for parking a car, summer kitchen or sports ground.
Wooden Stilt House
Despite modern advances in construction, some ancient methods of building construction have been successfully used to this day. A wooden stilt house is a typical method of construction, popular in many states. So in Russia, for many centuries, wooden houses were erected on wooden logs. They were often called "chairs." For such piles, trunks of those tree species that are characterized by a long service life are used. These include pine, oak, larch. The minimum diameter of such "chairs" to create a reliable foundation is 20 cm. The larger it is, the better. To extend the service life of wooden piles, they are treated with fire - burned. In the earth, scorched wood is difficult to rot, which makes it possible to erect structures whose service life is many tens of years (at least 30 years). Today, the treatment of piles with fire is often replaced by impregnation with special antiseptics or coating with bitumen.
Since today there is a sufficient number of high-tech piles made of metal available for sale, the construction of houses with the help of logs is being taken to the background. Most often they are used for suburban frame or wooden structures.
A stilt house, the photo of which is on top, would require digging quite deep holes under the logs. The minimum depth for digging in wooden piles is 1.25 m. They should abut against beams with a cross section of 10x20 cm and a length of 40-50 cm. Wooden piles are located in all corners of the structure and are located along its perimeter (with a distance of 1-2 m). Pit filling is carried out in layers of 20 cm. Each of them is carefully rammed. Top 30-40 cm backfill is made using fine granite crushed stone or gravel.
The disadvantages of wooden piles
Despite its popularity, wooden piles have been losing ground in recent years. This is due to such factors:
• difficulty digging logs;
• the need for additional processing of wood;
• short life of piles compared to other products of this type;
• the sale of more high-tech building materials;
• high price for quality wood.
Pile screw foundation
Foundations erected using screw piles have been used for a long time for the construction of military facilities. This specialization is due to the fact that their design allows you to build reliable supports for a variety of buildings in the shortest possible time. Abroad, the modern technology of building buildings on pile foundations was mastered dozens of years ago. It is used for the construction of residential buildings, farm buildings, as well as various industrial buildings.
In the Russian Federation, these bases have been used for a long time exclusively for the construction of lightweight structures, since the screw piles available on the market had a low bearing load. Recently, modern varieties of metal supports have appeared, which make it possible to make the scope of such building materials much wider.
Every year an increasing number of Russians erect the foundation of the house on stilts. This is due to the improvement in the quality of this building material and its affordable price. A house on
screw piles, reviews of which most of its owners are only positive, can become an ornament on any site. Most often it is a light structure made of wood. This type includes frame houses, and buildings from other light construction materials. Screw piles are used for the construction of playgrounds, baths, saunas, fences, arbors, greenhouses, terraces.
General information about screw piles
Screw piles for a house - the main element of the foundation. They are a steel pipe whose metal thickness is at least 4 mm. On the one hand, it has a point. At this end of the pile is a cutting blade, with which the support is screwed into the ground. Many people think that the use of such building materials will require the use of special equipment. In fact, the ideal shape of the blades of screw piles allows them to be screwed to the required depth with the help of 3-4 workers.
For the construction of objects with differences in height or with the presence of various lateral loads, piles with two blades are used. This design gives the foundation additional reliability. The diameter of the blades of screw piles varies in the range of 200-850 mm. The supports themselves have a diameter of 50-350 mm. The length of screw piles can be 2–11 m. Not only hollow, but also whole piles are on sale.
Advantages of Screw Piles
Anyone who has already built a house on stilts, reviews about them leaves mostly positive. The main advantages of these building materials include:
• the possibility of reuse due to easy disassembly without damage;
• lack of need to carry out significant volumes of earthwork;
• the possibility of building houses on mobile and flooded areas;
• speed of construction of the foundation;
• the start of construction of the building immediately after the construction of the foundation;
• the possibility of using for the construction of various extensions;
• long service life exceeding 100 years;
• acceptable cost, which is almost three times less than the price of the strip foundation;
• lack of construction waste on the site;
• the ability to replace or repair the foundation.
Due to the optimal perpendicular arrangement of the blades, a screw pile does not loosen it when screwed into the ground. The bearing capacity of such building materials varies in the range of 5-25 tons. For construction, piles with molded tips are chosen. The best protective coating of such supports is made on the basis of polyurethane resin. Very reliable galvanized piles coated with protection on the outside and inside.
The cost of the foundation of the screw supports depends on the size of the house. So, for example, a structure with an area of 6x6 m will cost 1-1.2 thousand dollars, and 9x12 m - 3-3.3 thousand.
Disadvantages of Screw Piles
Despite the fact that there are few shortcomings in these building materials, they still exist. Those who built the house on stilts, reviews about them leave mostly positive. Among the most common shortcomings, most developers distinguish:
• inability to use on rocky or coarse soil;
• foundation deformation, possible in case of violation of the device technology. It occurs when, during the screwing of the piles, their position was not fixed, the binding was improper, the screws were hammered or installed in dug holes;
• subsidence of soils resulting from poor-quality site survey;
• corrosion of piles with poor quality anti-corrosion environment;
• the impossibility of building large houses using heavy building materials.
Pile screw foundation design options
There are several design options for such foundations. They are selected depending on the type of future home and soil on the site. The most common of the foundation projects:
• single piles supporting individual structural elements, used when a small extension is made to an existing building;
• standard foundation, which is being erected for the basic elements of the building;
• pile tapes located under all walls of the house;
• pile field, necessary for the construction of the foundation for heavy structures.
Building a house on a pile-screw foundation
The house on screw piles is built in several stages:
1. The creation of the design of the structure and the calculation of the number of screws. Most often, piles with a diameter of 108 mm are chosen for frame and wooden houses. For smaller buildings, smaller screws can be selected, which will save money. When calculating the required number of piles, it should be remembered that with too often installed supports, the reliability of the foundation practically does not increase, but its cost increases significantly. One pile after filling it with concrete can withstand a load of 5-9 tons, so the distance between them during the construction of frame houses can be 3-5 m. The number of supports is increased when building two-story buildings or using heavier building materials. To increase the reliability of the pile-screw foundation, its bearing capacity is increased by 25-30%.
2. Marking of the site and its preliminary preparation.
3. The type of foundation is chosen depending on the mass of the structure under construction, the type of soil and the depth of its freezing. Begin construction with a geodetic study of the soil. It is necessary to determine the location of groundwater and stable layers of soil.
4. Piles are screwed into the ground according to the marks made. At the same time, soil compaction occurs in the screw area, which contributes to strengthening the foundation strength. These works can be carried out in any weather. Pile screw at least 3 workers: one monitors the level of support, and the other two screw it to the desired level. The supports are cut at a single level and poured with concrete. It enters the pile pipe, which strengthens the pile and prevents metal corrosion. After the concrete hardens, they proceed to welding to the support of the metal tip.
5. It is necessary to tie the piles to evenly distribute the load. Most often it is made from a channel. The upper part of such a foundation is called a grillage. It redistributes the load of the supporting structural elements.
6. Insulation of the pile-screw foundation is not required, since it refers to a ventilated type. Sometimes the grillage is insulated, but with improperly performed work, moisture may appear, reflecting throughout the building. To save heat in the house, it is best to warm the floor of the house.
7. On the prepared pile foundation, frame or wooden houses are erected.
8. The basement base is mounted.
Which stilt house to choose?
Weighing the pros and cons of choosing one or another type of support, we can say with confidence that the modern pile-screw foundation has more advantages than wooden. It surpasses the latter not only in technical, but also in economic and labor-intensive indicators. At the same time, its durability is many times greater than the service life of log supports.