Screw piles are steel pipes ending with a blade and a pointed tip. They are screwed into the ground like screws.
An important part of the pile is precisely the tip, since it performs several functions at once:
- is the supporting part of the pile;
- carries the load on the ground;
- prevents the displacement of piles from frozen soil during winter heaving.
The problem from the last paragraph is most often encountered in the construction of light wooden structures, using small piles. The only way to avoid meeting with expanded soils is to deepen the foundation of the house below the freezing line in the construction region.
Where are screw piles used?
Prefabricated inexpensive foundations for lightweight frame buildings - this is where screw piles are used, the pros and cons of which are discussed below, but for now, we will deal with their sizes.
What house are which piles?
For individual construction, the following types of piles are most often used: CB89x250, CB108x300, CB133x350. This abbreviation is deciphered as a screw pile with a barrel diameter of 89 (108, 133) and with a screw blade diameter of 250 (300, 350). The smaller the radius of the pipe, the lower loads you can trust it. If we are talking about light railings and small garden buildings, then a 76 mm pile will do; about verandas, arbors and brick fence posts - 89 mm; on small frame or log houses - 108 mm. And finally, if it is planned to build a spacious wooden house or even a foam block, then for this case piles with a trunk diameter of at least 133 mm are needed.
Like all building materials, screw piles have negative reviews , but they are no longer dictated by the unsuitability or unreliability of this type of foundation, but by improper use. Any construction requires a professional look and at least consultation, and as a maximum, an accurate detailed calculation of all structures and loads.
Screw piles: pros and cons
The construction of a foundation on screw piles has many advantages, such as:
- they are quick and easy to install, since they do not require preliminary drilling and concreting;
- you can engage in screwing piles year-round;
- complex relief and bulk soils are absolutely not terrible for them;
- they are mass-produced in factories, which means that their cost is much lower than that of traditional types of foundations;
- they can be twisted and unscrewed many times;
- they have good resistance to winter ground swellings.
Considering the screw piles, the pros and cons of these structures, one can not fail to mention that from year to year they are becoming more and more popular. And sometimes there are situations that can’t be done without them.
In contrast to everything that has been said about screw piles, consider the disadvantages that they have in comparison with their concrete “brothers”: they have a shorter service life due to susceptibility to corrosion in a moist soil environment, especially if their manufacturer uses low-quality materials and processing methods .
In general, the life of piles depends on many parameters that must be observed: on the thickness and grade of steel, on how professionally the seam connecting the shaft with the blade is professionally made, on the quality of anticorrosion coatings and on the mineral composition of soils. If there is a desire to purchase quality products, then it is necessary to require all passports, certificates and documents confirming the conduct and results of all appropriate tests.
Depending on how to operate the screw piles, the pros and cons can manifest themselves to a greater or lesser extent. For example, if I use it as a grounding method, then it will more likely collapse and rust, therefore, in the event of a zero conductor breakage, current will flow directly through the body of the structure. They can get negative screw piles if the house is built within a radius of 50 meters from a power station or cell towers. In such a terrain, a phenomenon called stray current, which accelerates electrochemical corrosion , is observed in soils .
Types of Screw Piles
Depending on which screw piles are used, the pros and cons, reviews about them may vary. There are 2 varieties of them: with a welded tip and with a cast one (in this case, the pile is an integral construction). The second option is more expensive, but more reliable, because the weld is the most vulnerable spot of the product.
Almost all negative reviews relate specifically to welded piles, because they are usually made in artisanal conditions with non-compliance with standards and GOSTs.
How to choose the right piles?
Welded can be used if you need to build minor structures such as fences and outbuildings. In other cases, preference should be given to cast, made of galvanized pipe. Anti-corrosion treatment of the blade will not solve the problem, because during screwing in, the friction is so high that all coatings are easily erased.
In order not to be disappointed in screw piles, they should be purchased only from trusted suppliers, of which you are sure of the quality.