Perhaps this representative of the family of interfloor stairs is the most spectacular. Sometimes it seems that its steps are floating in the air. But this is only an illusion, in fact, in front of you is a carefully thought-out engineering design.
The traditional wooden staircase on bowstrings or stringers, with its massive pillars, obligatory risers, chiseled balusters and wide handrails, creates a feeling of solidity, but at the same time blocks the light flow and limits the field of view. In other words, it requires a lot of free space. Modern interior styles do not tolerate such extravagance: designs should be light and transparent, lines should be simple and swift.
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1. The main support of this unusual staircase is the cantilever brackets, the auxiliary support is the ceiling ties. The design has retained its visual lightness, despite the fact that its steps are quite massive, and thanks to the handrail and the rope fence, it is very convenient and safe to move along it.
2-4. The cantilever principle is widely used in the manufacture of spiral staircases. The node of their attachment to the pole can be made so that the step does not need any additional support. The pillar will have to be made more massive, but neither a bowstring nor a stringer will be required.
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5. Usually the steps are strung on a central pole, installed at a distance between the ceilings, and pinched with the help of spacer bushings.
6. Bolts and miniature wall brackets are used to stiffen the structure.
7, 8. The laminated tempered glass railing (7) has a significant mass, so it is almost never supported on steps, but is attached to ceilings. Such railings can become additional support for the march, and steel brackets attached to the wall (8) take on the main load.
In response to the requests of designers, new types of stairs appeared: cantilever, suspended (on strands), bolt, spinal (on the central stringer) and combined. Probably, the dream of fans of minimalism and high-tech style is fully embodied precisely by console models, in which there are no extra details, only steps, moreover, attached to a support (wall, pole, column) with only one end, while the second is free " floats" in the air. They try to make the fencing of such stairs as less noticeable as possible, and in radical versions they do without railings at all. But still it should be noted that such extremes are rare and are designed more for demonstration than for practical application. And the cantilever steps themselves in their pure form are rarely seen, usually this mount is combined with other support nodes.
As a rule, cantilever stairs are not sold ready-made, they are made according to the size of a particular room and taking into account the requirements of the owner of the house. When fulfilling such orders, European companies take one of their catalog models as a basis and use factory components, making a minimum of changes to the design (due to this, their products are of consistently high quality). Domestic firms produce mostly piece goods.
Building a cantilever staircase is a difficult and time-consuming task. Its foundation must be laid at the stage of erecting the walls of the building (or, at least, before the start of interior decoration), because each step must withstand a load of at least 150 kgf applied to its hanging, that is, unsupported end (and this is in addition railing weights!). Such high strength can be achieved in various ways.
Step termination. During the construction of the wall, the ends of the steps are embedded in it for a length of at least 200 mm (with a maximum march width of 800 mm). This is feasible only if the masonry is made of bricks or sufficiently heavy (for example, solid expanded clay concrete) blocks, and it is necessary that each step be pressed down by at least ten rows of masonry. When using porous ceramic and hollow claydite-concrete blocks, as well as slotted bricks, the embedment depth must be increased to 300-400 mm, which does not always allow the thickness of the wall to be made. During the construction of aerated concrete, it will be necessary to strengthen the place of embedding each step with embedded elements of heavy concrete. Steps are also not suitable for everyone, but only made of very hard and elastic materials, such as reinforced concrete. However, they are quite easy to decorate with wood overlays, laminated panels, natural or artificial stone. And you can leave the steps in their original form - nothing better can be found for a loft-style interior.
Attachment of brackets. Sections of a profile pipe up to 1 m long are embedded into the wall to a depth of 250-300 mm, leaving outlets equal to approximately 2/3 of the step length. At the same time, the requirements for the wall are not reduced at all, but the steps can be made of engineered solid wood, as well as materials based on wood composite (chipboard, MDF). The fact is that in this design they cease to be self-supporting, but rely on steel brackets. Metal parts, as a rule, are hidden in grooves or holes milled (drilled) in steps. It should be noted that for the implementation of projects with pinched and walled-in consoles, only leading construction companies should be contacted, and architectural supervision is a prerequisite for success.
Anchor fastening. The method is applicable after the completion of the main construction, but will require welded brackets with support platforms. Each such element is fixed to the wall with four or more anchor bolts with a length of at least 150 mm and a diameter of 10 mm or more. The requirements for the material of the enclosing structure in this case are very strict: neither the porous block nor the slotted brick will hold the anchors (or, in order to reduce the pull-out force, the support platforms will have to be much larger).
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9. Creating more and more original architectural forms is becoming a great way for manufacturing companies to demonstrate the skill of their engineers.
10-12. High-tech style corresponds to products made of aluminum, glass and plain laminated panels (10, 12). Solid wood steps with chrome handrails emphasize the eclectic interior (11).
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13, 14. When making a custom-made fence, you can give free rein to your imagination, for example, decorate poles and balusters with inserts made of copper, brass, bronze or cut glass. It is only important not to overload the supporting nodes and not to violate the stylistic unity of the interior.
15. Glass steps always require bolt support as they only allow short wall brackets.
16. Only the most experienced specialists undertake the design and construction of reinforced concrete stairs.
If the wall does not have the necessary strength, this is a serious obstacle to the construction of a cantilever staircase. But still manageable. Let us describe the method of fastening steps, which can be implemented in almost any building before the start of finishing work. Its essence is the use of a powerful welded metal frame from a channel or a profile pipe. The design is made up to the ceiling, for the entire length of the march, placed close to the wall and tied to the upper and lower ceilings. Cantilever supports for steps are welded to the racks (or bolted). The frame is then hidden with drywall sheathing or lightweight block masonry.
The most complex type of cantilever staircase with brackets welded (screwed) to a single steel bowstring, which is attached to the ceilings by means of powerful support platforms and anchors. So that the bowstring does not twist under load, it must itself be a complex welded truss with longitudinal, transverse and diagonal stiffeners (like a tower crane boom). And yet, even a well-thought-out and well-made console (except for a wall-mounted one) does not completely get rid of the unsteadiness of the steps. First of all, the staircase should be safe and comfortable, and what kind of comfort can we talk about if you feel deflections and backlashes at every step? We have to look for ways to strengthen the structure.
The task of engineers is to create a not too noticeable, but sufficiently reliable support for the second end of the steps. For example, you can rigidly connect all the treads to each other with the help of bolts and thus transfer the load to the floors. Bolts are called hidden bolts used in conjunction with spacers. In the case of a cantilever structure, each pair of steps is connected with just one such bolt (and not two, as in a typical bolt), located at the posted edge. Since the main load is taken by the wall mount, the bolts can be made miniature and disguised as the details of the fence or hidden inside the risers. On the other hand, the use of bolts makes it possible to significantly simplify and reduce the brackets: a pair of rods with a diameter of 30-40 mm and a length of 400-600 mm, embedded in the wall by 80-160 mm, is enough for each step.
Fastening steps to the ceiling with strands is no more difficult than a bolt connection. It is only necessary to purchase stainless steel cables 8-10 mm thick and install screw hooks that allow you to select the slack of the strands, turnbuckles. Hanging ladders look even more airy than bolt ladders.
The editorial staff thanks the companies "White Maple", "SM Square", Euroscala, UNION
for help in preparing the material.
