DIY foundation on screw piles: phased construction
Budget construction requires a smart approach to materials and savings. The foundation is one of the most costly construction stages, accounting for about a third of all costs. Is it possible to somehow reduce spending? It turns out there is! Moreover, this method of arranging the base of the house not only allows you to save money, but also guarantees high strength and durability of the building. Meet the foundation on screw piles. To make such a structure with your own hands is quite within the power of any more or less competent builder. Its advantages and disadvantages, installation and finishing features are all about this in our material.
The use of pile supports allows you to create original structures without disturbing the natural landscape
The content of the article
- 1 Screw pile foundation: main advantages
- 2 Pile foundation with monolithic grillage: reliable and durable
- 3 Cons of the pile-screw foundation and ways to eliminate them
- 4 How to choose screw piles for the foundation
- 5 Calculation of the pile-screw foundation
- 6 DIY pile foundation: step by step instructions, video
- 7 Construction of communications in the pile foundation
- 8 Foundation repair with screw piles: basic methods
- 9 SVF finishing
- 10 Outcome
- 11 Video: replacing the foundation during the reconstruction of a wooden house
Screw pile foundation: main advantages
The pile-screw foundation is suitable for wooden, frame houses and foam block buildings. This technology cannot be called new - it has long been used in industrial construction. For individual developers, such foundations are still a novelty, but they are gaining popularity more and more rapidly due to an impressive list of advantages. Let's consider in more detail why it is worth dwelling on this type of foundation:
- Impressive construction speed. To install such a foundation, even with a complete lack of experience, will take only about 12-14 hours. And install piles it is possible without the help of special equipment, manually. It only takes two people to do this job. So if there are no good access roads to the construction site, this is not an obstacle to work.
With a mechanized installation, the whole process will take only three to four hours.
- The ability to install almost anywhere. The screw supports will form a solid, high-quality foundation, even in swampy soil. Want a house over water - easy! If you want a building on a steep slope - no problem either. And what is most remarkable, the terrain and the ecological state of the site will not be affected in any way either during the work or during the subsequent operation of the building.
Minimal, targeted intervention in the ecosystem will allow you to install a house even in the forest among century-old trees, without disturbing the natural landscape
- Impressive service life. A house on a pile foundation will stand for at least a century. So the safety margin will be enough for more than one generation of its owners. And if you approach the construction with special diligence and additionally process the piles with a protective coating, the service life of such a foundation will at least double.
- Possibility of installation at any time of the year. Heat, frost or rainfall - nothing will hinder the installation of piles. The only thing worth worrying about is the health of the builders, but otherwise the installation can be carried out when necessary. Weather conditions will not affect the results in any way.
- Excellent load and strength data. Depending on the size, the screw mounts can support up to eighteen tons. For example, for a wooden house, a bearing capacity of three tons is sufficient, for bricks and a block - nine. The load on the ground with this type of foundation is evenly distributed. Another important aspect is that the SVF (pile-screw foundation) is highly resistant to seismic vibrations.
The use of such structures is recommended in areas where the threat of earthquakes is not excluded.
- No form restrictions. On the SVF you can build structures of any shape - square, round, with bay windows and towers, columns and terraces. If necessary, it is easy to attach a wing or veranda to the building. You just need to install additional supports and connect the grillage.
- Low cost. The pile structure can be called one of the least expensive in construction. It will cost about half the cost of a strip foundation.
And if you still have any doubts about the advisability of choosing in favor of a pile foundation, let's compare two types of structures:
| Pile | Tape |
|---|---|
 |  |
| The length of the supports is selected in such a way as to compensate for differences on the ground. | In the presence of complex relief, leveling of the site is required. |
| The installation does not require excavation, the landscape of the site remains in its original form. | The arrangement requires a large amount of earthwork. |
| The supports are installed by the efforts of two people without the use of special equipment. | Reinforcement requires welding. Pouring with concrete without mechanized fixtures is time consuming. |
| The foundation can be used immediately. | After pouring, the base must withstand at least a month to gain the necessary strength. |
| Installation of piles is carried out at any time of the year, regardless of the air temperature. | It is advisable to carry out concrete work at a temperature not lower than plus five degrees. |
After all these arguments in favor of screw piles, only the following questions remain:
- How to choose supports for your home?
- How to properly mount the pile foundation?
- How to make a grillage correctly and do you need to additionally strengthen the strapping?
- Does such a house need a blind area and how to sheathe the foundation?
Related article:
Pile foundation: calculation. To equip the pile structure, it is necessary to accurately calculate the number and size of the pillars, their depth and location. You can make these calculations yourself, using the information, algorithms and recommendations that are offered in our material.
Pile foundation with monolithic grillage: reliable and durable
The foundation on piles with a monolithic concrete grillage is usually placed in areas with complex soil. Pile supports transfer the load from the building to denser soil layers, and the monolithic grillage evenly distributes this load. Such bases are suitable for almost any type of building: from foam blocks, wooden, frame.A similar foundation can be used not only for a residential blockhouse, but also for baths, for fence brick, garage or carport.
A great example of using screw piles for a metal trestle
Such a construction on the site will be useful to any motorist. An overpass can be installed from 9-14 piles without the use of concrete pouring. A metal welded grillage is enough.
The combined reinforced concrete foundation on pile supports is far superior in strength to a conventional shallow foundation. The wood or metal of the grillage is subject to the adverse effects of external factors, and cast concrete structures can stand for centuries.
Types of SVF with concrete grillage:
- hinged. A distance of up to a meter in height remains between the floor level and the ground;
- terrestrial. In this version, the grillage is placed directly on the ground or deepened into the ground, forming a low base of the required size. The recessed structure is not placed on heaving soils; seasonal movements can split the concrete slab.
Important! The concrete structure in the SVF should not be in direct contact with the ground. If a recessed foundation is made, the bottom of the grillage is insulated with waterproofing materials.
For a foundation with a concrete grillage, use screw, driven or bored piles
Drives are rarely used under a house in private construction. Their installation requires the use of special equipment. But screw and boring is a more common option. They can be installed manually. Screws are screwed in by the efforts of two people, and for borers they drill wells, install formwork in them, reinforce and fill with concrete.
House near Taldom 10x10 on a concrete grillage
Experts recommend using a combined base for a stove or fireplace. Such a heavy structure in a wooden or frame house requires a separate foundation. For this purpose, the piles are placed by the cluster method - several pieces next to them with a minimum distance, and then tied with a reinforced concrete sole.
This correct approach will ensure the stability of the structure and the absence of skewing of the entire base due to uneven load distribution.
It makes no sense to install concrete grillages for a greenhouse, for a gazebo or for sliding gates. The loads on these objects are too small, and the costs of reinforcing and pouring reinforced concrete will not be justified. In all these cases, it is easier to use the light eco option - the usual screw piles, selecting their bearing capacity for a specific object.
An example of a 6 by 6 gazebo on piles
Cons of the pile-screw foundation and ways to eliminate them
We examined in detail all the advantages of the SVF. But it would be correct not to forget along with the pros and cons. Forewarned is forearmed. Keeping this principle in mind, let us study the possible disadvantages of the pile foundation. If you take them into account and compensate for all the weaknesses during the installation process, you can not worry in the future whether the foundation is reliable, subsides or not, and what is its durability.
- The service life of the metal is limited. All its weaknesses are especially manifested in the absence of proper processing and the use of used pipes. Corrosion damage to piles can be prevented by selecting a material with a modern coating - epoxy enamel, galvanizing or polymer "jacket". You should not skimp on this most important moment.
Moisture in the soil can "eat" your foundation in a matter of years if it is not protected by a reliable coating
- The need to monitor the progress of work.Manual installation of screw supports is not just an economical approach to construction, but also an important part of ensuring that they are securely fixed in the ground. Do not trust this work to unfamiliar specialists. This is exactly the case when it is better to do everything yourself. An under-rolled or crooked pile that is not firmly installed in dense soil layers will lose its bearing capacity.
- Refusal from the basement or basement floor. This disadvantage is perhaps the most significant of all. In a private house you cannot do without a basement. But it will not work to dig it up in the locations of the SVF. Any excavation work will weaken the strength of the supports. The only way out is to dig a cellar away from the house. Not everyone will enjoy running in the winter for a jar of jam to the far end of the site. So when deciding what to choose, a tape or a screw foundation, think about the need for a basement and the possibility of arranging it elsewhere.
A separate cellar is a necessity for a pile type of house foundation
Note! Previously, the lack of columnar or screw bases was considered the impossibility of mounting supports close to the existing structure. Now this problem has been solved - there are special rotators with which you can install a pile fifteen centimeters from any foundation.
Having considered all the arguments, we can say with confidence that when asked which is better, a strip foundation or screw piles, we can confidently say that SVF is more economical and easier to install, but on the condition that the piles are reliably protected and the house does not have a basement.
And it would be possible to end the conversation on this about the shortcomings of SVF, but today, literally on the heels of this technology, know-how in construction is coming: the TISE method. This installation option involves the use of a special drill, which creates depressions in the ground with an extension at the end, the so-called "cup".
This shape of the column allows you to actively resist heaving of the soil
Let's consider which is better: TISE or screw foundations:
- What is cheaper: screw, since they do not require special equipment for installation.
- Where can they be installed: screw - literally on any soil, TISE are not suitable for areas with a high level of groundwater and rocky soil.
- When can it be installed: TISE, like any concrete foundations, is limited by the temperature regime of installation. Screw piles can be installed at any time of the year.
- Maintainability: the screw pile can be replaced with a new one, TISE are not repairable.
Considering all of the above, it should be admitted: screw piles are the best foundation option for a lightweight house. Their few shortcomings can be easily compensated for by a competent installation.
How to choose screw piles for the foundation
The correct selection of materials is the key to the strength of the entire structure. This also applies to screw supports. How to choose the right screw piles for the foundation?
Blades
Piles are of two types:
- broad-lobed. The diameter of the blades is one and a half to two times the diameter of the trunk. Such supports are ideal for loose soil and low bearing capacity, for peatlands, sands and the bottom of a reservoir;
- narrow-lobed. The diameter of the propeller blades is equal to or slightly larger than the diameter of the pile. These supports are suitable for dense soils, including permafrost areas.
The blades can be arranged in one row (single-blade piles) and in two or three rows
Multi-blade piles have an additional level of fixation and are used on difficult, floating soils. They have good resistance to pressing and pulling out. At the same time, the installation of such supports requires additional effort and control. When deciding which piles are better to choose, it makes sense to focus on multi-blade.
Handpieces
Metal pile caps can be cast or welded. Welded ones are made of heavy plate iron. Their blades are welded to the tip. Such attachments are less resistant to stress and may deform during installation.In addition, weld spots are an additional risk factor for corrosion.
Cast tips will cope even with stony soil, their safety margin is higher than that of the pipe itself
Metal
Steel marked CT3 is suitable for soils with a low level of chemical activity. For aggressive environments, it is better to use CT20.
Coating
A high-quality coating will not only facilitate the process of installing the support, but also keep it for a long time. Manufacturers offer four types of support processing:
- polymeric (the support is covered with heat shrinkable material);
- epoxy (epoxy based compounds);
- zinc (cold and hot galvanizing);
- polyurethane (based on polyurethane resins).
Each of the listed coatings has its own characteristics. The most durable are piles and galvanized and covered with heat shrinkage.
Calculation of the pile-screw foundation
An online calculator can be used to calculate the bearing capacity of a support.
Calculator for calculating the bearing capacity of a screw pile
The basic principle for studying the permissible load is based on data on the nature of the soil and the dimensions of the support. If you do not have complete information about the nature of the soil on the site, the calculator will make calculations based on the average values laid down in the SNiP. When deciding on the installation of the structure on site, it is worth laying additional support points for greater confidence in the strength of the base. Now you have an idea of how to calculate the bearing capacity of one pile.
Calculator for calculating the total load on the pile foundation
After calculating the bearing capacity of one support, it is easy to calculate the required number of piles. To do this, you need to find out the load of the entire building. The second calculator will help to calculate the weight of the building. It takes into account the weight of walls, ceilings, roofs and even the finishing of the building.
For calculations, you should indicate the dimensions of the future structure, the materials that are planned to be used for the construction of the house. The program will offer to select the types of floors from several options, as well as the shape and materials of the roof. For accuracy in the calculation, it is proposed to take into account the types of finishing of the building (ideally, the weight of people and furniture should be added to the result obtained). The result will be the result in tons.
To calculate the number of piles, it only remains to divide the total mass of the building by the bearing capacity of one support.
DIY pile foundation: step by step instructions, video
SVF is easy to install with your own hands. The technology is extremely simple and does not require any special skills and knowledge.
Step-by-step instruction:
| Construction stages | Picture | Description |
|---|---|---|
| Test screwing |  | A test screwing will help to study the bearing capacity of the soil without costly research. |
| Design |  | To calculate the required number of piles and their size, it is necessary to study the soil at the site. The main goal of the study is to determine the level of occurrence of dense soil layers capable of firmly fixing the support. To obtain reliable results, you can turn to professionals who will take soil samples at the site and make all the necessary calculations.You can determine the depth of the supports yourself. To do this, a meter-long hole is dug on the site away from the site for the foundation, and then a deepening is made with a garden drill. In the course of work, you will be able to determine where the dense layers of the earth begin and what the level of occurrence of groundwater is. To calculate the bearing capacity of the pile, you can use a calculator, or go the extremely simple way - install the supports in two meter increments, adding points at the intersections of the walls and at the locations of the stove or fireplace. The recommended pile size for a project for the construction of an individual house of lightweight construction (wooden or frame) is 108 millimeters. |
| Marking on the site |  | The markings on the site are made using a conventional building level, tape measure and twine. All you need to do is mark the points of the location of the supports in accordance with the diagram and pull the string to determine the level to which it will be screwed. |
| Well preparation |  | So-called pits are made at the marked points. They can be made with a regular garden drill. The depth of the wells is from seventy centimeters to one meter. Such wells will help to accurately align the pile and greatly facilitate the entry of the screw into the ground. In addition, the three-meter support will be difficult to screw in manually if it is not buried in the pit. |
| Screwing in piles |  | To calculate the time to install each support, you need to measure the pitch of the propeller blade. For example, a step of five centimeters will require about forty turns to install a support two meters deep. It will take three people to install the support. A crowbar is inserted into special holes, two people screw in the pile, and the third checks the correct entry of the drill with a building level. After significant efforts are required to turn the support, screwing is stopped. The pile screw has reached a dense soil layer. You can mechanize the process using a gearbox and an electric motor. In this case, the fate of only two people is required: one holds the screwing device, the second checks the correct installation of the post. |
| Horizontal undercut |  | After all the supports are installed in their places, it is necessary to mark the places for cutting them using a level or laser level. Piles are cut with a conventional angle grinder (grinder). To build a wooden house on piles, you need to install heads. They are secured by welding or bolts. The heads are provided with mounting holes for fixing a wooden or metal grillage. |
| Concreting |  | To prevent the support from rusting from the inside, it is filled with concrete mixture. For this purpose, dry backfill is used, which is subsequently cemented from internal condensate or classical concrete filling. Filling the supports with concrete will give them additional rigidity and strength, even with thin walls. |
| Installation of grillage |  | Experts recommend installing the grillage at a height of about half a meter from the ground level. This distance will allow you to keep warm floors in the house and create natural ventilation. There are three main types of grillage: wood, metal and concrete. To create a monolithic grillage, formwork is formed, reinforcement and concrete pouring are performed. A waterproofing material must be placed under the monolithic slab. The wooden grillage is a bar with a cross-section larger than the planned wall thickness. It is attached to the heads with bolts or self-tapping screws. The iron grillage is made from a channel or I-beam. All joints are double seam welded. |
| Summing up engineering networks |  | It is better to start communications at the stage of installing the SVF. Later, the work will be complicated by the need to open the floors. The space between the ground level and the future floor is enough to install all communication nodes without interference. For water supply and sewerage, it is necessary to provide insulation in advance. |
| Finishing |  | The last stage of work involving the sealing of the walls with decorative material. The presence of walls will allow in the future to fill up the subfloor with dry backfill and to keep the tops of the piles from the destructive effects of external factors. |
In more detail the whole process of installing the SVF foundation in the video:
Construction of communications in the pile foundation
SVF pipes rise at a level from half a meter to a meter above the ground. This distance between the piles and the ground allows you to install all the necessary engineering networks without any problems:
| Communication | Construction description |
|---|---|
| Water pipes | Installation of water pipes in the SVF foundation implies a solution to the problem of their insulation. To do this, use mineral wool insulation and polystyrene winding. In areas with harsh climates, self-regulating heating cables are used. They will maintain the optimal water temperature and prevent ice plugs from forming in the pipes. The cable can be installed both inside and outside the pipe. |
| Sewerage | Water draining into the sewer system is at room temperature, so they do not need to be insulated as thoroughly as the water supply. One layer of mineral wool strapping will be enough. |
| Earthing | It is not recommended to use supports with a grillage for grounding the power supply system of the house. Passing currents will lead to premature destruction of the foundation. For grounding, you should create a free-standing structure of three piles, tied with metal wire. The posts for such a device should not be covered with a protective layer. |
| Electricity | If the electrical networks enter the house in the area of the basement, they must be protected by a special casing. |
What else is important to know when equipping a SVF:
- A pick is used to isolate the distance between the ground and the floors of the house. This imitation of a plinth is made from siding or corrugated board.
You can make an extension of brickwork, but you will need to prepare the base for it
- The false base is necessarily supplemented with a blind area, which provides additional waterproofing of the underground. Considering that the SVF does not shrink, all these works can be carried out immediately after the foundation is installed.
- The empty space under the floor should be covered with sand and gravel. For natural ventilation, vents are left in several places.
Foundation repair with screw piles: basic methods
Sometimes there are situations when the existing foundation cracks or begins to sink rapidly. If the foundation is not strengthened in a timely manner, the entire structure may suffer.
Distortions in window and door openings, subsidence of floors can become alarms.
All these symptoms require immediate treatment - reconstruction of the foundation. And it is better to do this before cracks appear on the walls and basement.
Reasons for damage to the foundation:
- neglect of reinforcement of supports by concrete pouring;
- incorrect distribution of the load on the foundation;
- use of materials of inadequate quality;
- violation of technology;
- systematic flooding.
The easiest way to solve the question of how to strengthen the existing base is to use screw supports. This technique is the most economical and easy to implement.
There are two methods for repairing a foundation:
- A wooden or frame house can be raised above the foundation using a jack system and the columnar ones can be replaced with screw piles. Replacement can be complete or partial.
- A new base is made to the side to fit the size of the house, and then the entire structure is moved to a new location using a crane. This method is expensive but considered the most reliable.
Before choosing one or the method, it is necessary to study the state of the structure and the possibility of its transportation to a new place or lifting on jacks. Dilapidated buildings may not withstand such procedures
After repairing the foundation, it is necessary to decide how to close the new foundation. Roofing material should be used to cover all joints of walls and grillage. All metal parts of the foundation must be painted with epoxy paint, and the wooden parts with anti-mildew and insect repellent.
It remains only to choose a way to finish the base. There are many interesting solutions for the design of SVF, which should be discussed separately.
SVF finishing
The screw foundation can be designed in different ways. For cladding, basement siding, stone tiles, polyvinyl chloride panels, and ceramic tiles are used.
Important! So that the decorative cladding does not suffer with seasonal movements of the soil, a small gap of about five centimeters should be left between it and the ground. Close the gap with a strip of mesh or other material.
In order not to add loads to the base, experts recommend using light materials for decorating the basement
Decorative materials are attached to metal or wooden planks. For insulation of the foundation, you can use expanded polystyrene skirting or stone wool. The last stage of finishing will be the creation of a high-quality blind area that diverts storm water from the house.
The simplest option is a blind area of paving slabs laid on a waterproofing film
More details on how to insulate and how to finish a pile foundation in the next video.
Video: finishing the pile foundation
Outcome
The pile-screw foundation is an easy-to-install and cheap construction. With all this, the base on screw piles is distinguished by its reliability, durability and maintainability. When choosing piles, you should pay attention to the quality of the material. It is better if the screws are cast, the coating is zinc or polymer. All installation work can be done by hand, but you should first study the nature of the soil at the construction site.
Video: replacing the foundation during the reconstruction of a wooden house
Loading... See also:
Pile foundation: calculation of the number of piles, bearing capacity and load 
Rostwerk: what is it, its types and purpose 
How to choose the right base, or Types of foundations for a private house 
Screw piles for the foundation: price with installation, types, production and installation 
How to make a columnar foundation with your own hands: step-by-step instructions with photos and videos 
Do-it-yourself rafters for a gable roof: design and installation
