Pile foundation in many cases is preferable to other types of bases, especially in the field of low-rise construction, as it allows to save considerably on its erection. The stage of tying the screw piles with a bar is mandatory and is one of the most complex and responsible. But before considering the order of its conduct, it is necessary to understand why this should be dealt with and how important it is at the same time quality.
What is a pile? A hollow tube of high-quality steel, which has one tapered end with welded "blades".After it is screwed into the ground above the surface, only a part of the "trunk" rises, on which there are diametrically drilled holes( technological).After the installation of the piles and the preliminary alignment of the "tops" are finished, they are cut off. How can I mount the walls of the house? That is why before starting to erect them, the masters are engaged in the installation of a kind of "interlayer" between the base and the structure itself.
Why do I need a harness?
It solves several tasks:
- rigidly connects all installed piles to a single structure;
- allows to make more accurate alignment of their upper slices in the same plane( horizontal), since it is difficult to avoid during the process of screwing the supports of technological errors, especially if the work is done on its own;
- evenly distributes the entire load on the foundation along the perimeter;
- partially protects the walls from the effects of the soil.
Various methods are used for binding( for example, the construction of grillage is one of its varieties) and the materials are a log, a channel( shown in the figure).
But still the best option is tying not just wood, but a bar, as it has a rectangular cross-section, which simplifies the work on its installation( including the mounting of the lower row of walls).
Single strapping
The most effective way is combined, in which two methods are combined - fixing with screws( anchors) + clamps( corners, plates).
Installation of
heads These elements are attached to the "tops" of all piles. As a rule, these are metal plates that are welded to the ends of the supports.
But in case of tying timber, given its strict dimensions, it is advisable to install flanges( the letter "P" in an inverted form).The distance between the "legs of the letter" depends on the parameters of the workpieces, since they will be stacked between them( the minimum cross-section of the bar for the strapping is 150 mm).Naturally, the holes for fasteners are prepared in advance.
Preparing blanks
The cuts are made at their ends, and the type of connection of the timber to choose is decided by the master. It is clear that the first is much simpler and does not require much experience, but it is less reliable. In addition, slots for lags are prepared.
Laying and fixing the beam
The first thing you need to do is lay all the flanges with a waterproofing material( the cheapest one is ruberoid).As an option - bitumen + film p / e. The task - the wood should not touch the metal. At least because on it during operation it will condense the moisture and gradually become absorbed into the bar.
Work always begins with corners. The first 2 adjacent bars are pre-joined, aligned, after which the connection is checked for 90º( using a square).After an additional fit, the workpieces are fastened with hardware. Self-tapping screws are much better than nails, as it is easier to remove them if necessary. For the rest of the corners - the same.
The laying of the bar on the sides of the complexities does not represent, considering that all products have the same( calibrated) length. Their connections, from the standpoint of maintainability, it is desirable to do "butt".Between them they are fastened with metal plates and staples( the possible variants are shown in the figure).
Inside the perimeter, the technique is not much different from the above( example - in the figure).
All joints, in order to avoid the appearance of "cold bridges", it is necessary to warm( for this purpose it is expedient to use jute tape).
Treatment of the
strapping As a rule, the bar is covered with bituminous mastic, on top of which the waterproofing material is applied. After this, you can proceed to the next stage of construction.
Special feature of double strapping
It is considered more reliable and maintainable.
The technology is not fundamentally different, but there are a few nuances:
- for the 1st "level" is taken beam 200 mm;
- for the second - section 100 x 150;while laying the second row is carried out by installing the blanks "on the pop"( the smaller side);
- in the 2-nd level do not cut for lags;
- the joints of the joists along the rows must be spaced apart.
Useful advices
- For binding, we recommend a bar made of softwood. The best option is larch. Since the material will be located directly above the ground, then it will be intensively affected by moisture. Its effect is reduced by various impregnating compounds, but they also have a validity period. The peculiarity of larch is that this tree becomes stronger only when wet.
- After the end of welding, all the places exposed to temperature influence, it is advisable to treat with anti-corrosive composition. The fact is that the piles have a protective coating, which is damaged by welding.
- For more accurate alignment of the bar horizontally at the place of its placement on the flange or a wedge is placed, or a small drink is made.
- In the absence of grillage, it is possible to further strengthen the foundation with "jagged" metal.
There are recommendations, how to make a binding for "gluing together"( like a bar) from the boards. And the argument is given - it will be cheaper. No matter how masterfully the text is written, no matter what advantages such a technique may be given - the should not be done by .Perhaps, "homemade" and useful in some other place, but if it comes to the foundation, it is better not to experiment - any rework will be much more expensive.
