Stringers for stairs (57 photos): what is it, a structure on a metal beam and on a central monokosour, calculation of the structure on one metal element and fastening of steps

A beautiful home means, first of all, well-designed details. Coziness and comfort should be present in every corner of the space, which is why it is worth approaching the creation of an interior thoroughly, thinking over every little thing.

The staircase should not only comply with building codes in such a house, but also be attractive. That is why kosoura receive special attention in its design.

What does the structure consist of?

Not everyone knows what a kosour is, because they do not assume that a staircase is a special structure consisting of several elements. Violation of the interaction between them leads to a decrease in the level of security.

Supports play an important role in the organization of spans between the first and second floors. It is they who are called kosoura. The element is presented in the form of ladder beams located on each flight, to which the steps are attached. When viewed from the side of the entire structure, you can see their end.

The detail helps to create a special style, to give originality to a simple staircase. Often this element is used in the design instead of a bowstring, but they have the same function. It is the stringers that help to visually reduce the staircase, make it not so large.

The element must, according to the standards, withstand the weight of a person and even objects lifted to the second floor, there can be no question of any vibrations. If, when lifting, it is felt that the kosour is trembling or swaying, it means that a gross mistake was made during its construction.

The difference between an element and a bowstring

The bowstring looks very similar to the stringer, but the main difference is the way of installation. The tread is formed from the inside, and such a connection is a tie on which the structure is held. The combs are not cut out, as in the stringer, but are selected, that is, they are milled.

They differ from the string of the stringers by the sizes. The shape depends on the type of future steps and the degree of load. These factors cannot be ignored as they play an important role. According to building codes, a weight of up to 250 kilograms per staircase is permissible.

Classification and types

Playing the role of a support for the stairs, the stringers duplicate the gaps and step of the structure. The elements are arranged parallel or at the appropriate points, they are also called nests. If we consider the classification from the constructive point of view, then they can be:

  • straight;
  • broken;
  • screw.

Straight lines have overlays for steps, on broken lines a turn up to 90 degrees and a platform, that is, between the 1st and 2nd floors, the staircase has two different halves.

Screws always have a spiral shape, the binding is carried out on the central axis, which is often a pillar. If the gain is good, this reference axis is conditional.

The site is the space between the flights of stairs, which is a horizontal surface through which there is a demarcation between the first and second half of the structure. It is necessary, because due to it the second flight of stairs can reach the point specified in the drawing, while maintaining not only the angle of inclination, but also the proportions. Often the base stands on two beams or is rigidly tied to the vertical.

Monokosour stands on one beam. It is permissible to install it to the center or ends of the treads, but in this case it is imperative to additionally fix the element to the wall. Special requirements for the beam, which must be wear-resistant, therefore it is better to use a steel pipe. Such a staircase can be erected only with the permission of the construction supervision.

Kosoura can be divided into two large groups: stepped and with filly. The latter are a triangular element attached to the beam. Treads are installed on them. The design is considered complex in execution, but the most reliable.

Wooden stringers have their own classification:

  • straight;
  • comb;
  • rounded.

Straight lines are used in the construction of such marches, when erecting overhead steps, a comb is used, and rounded ones are ideal for stairs of the same shape.

Execution materials

There are several materials that can be used to create stringers without disrupting construction technology.

String ladders can be made of wood, which makes them better than bowstrings, as the weight is significantly reduced. It can be a log, a bar or a board. With a small stairwell, the option is advantageous. In addition to wood, it is necessary to highlight several types of materials.


  • profiled pipe;
  • metal profile;
  • I-beam


  • plastic, which contains wood fiber;
  • metal-plastic.

Composite material

  • wood-metal;
  • metal-polymer.

Reinforced concrete

Low cost and reliability made metal and wood the most demanded in the organization of stairs. Combined models are necessary in the formation of a complex structure, when the project cannot be called standard, and its visual appeal does not cover safety requirements. Steel structures are in particular demand due to their strength and reliability.

Massive reinforced concrete structures are formed during finishing work. They have a lot of weight, so the base for them must be calculated at the stage of creating a project. Subsequently, it will be placed parallel to how the foundation is laid.

Structural calculation

Before erecting a staircase, it is necessary to calculate the basic values ​​and only then create a project. You definitely need to know:

  • the height of the stairs;
  • width and height of openings;
  • length, how much is the projection on the floor;
  • the height of the risers;
  • the depth that the treads have;
  • the total number of steps.

The total height is determined from the floor of the first floor to the floor of the second. It should not be less than 2 meters.

The projection is defined as the dimensions of the allotted space for the staircase. There are no specific requirements for the depth, this value is usually arbitrary and is selected based on personal preferences, the main thing is that it is convenient for the user. Most often it is 25-30 cm.

It is worth paying special attention to the height of the steps, which should not be more than 22 cm. The lower this figure, the less effort must be made to climb to the second floor. The total number of steps in the construction of a ladder is determined taking into account the length of the stringer and the height of the riser.

If the height of the stairs is 250 cm, the length is 400 cm, and the depth of the tread is 28 cm, then the number of steps can be found by dividing the length of the structure by the depth. In this case, it turns out 14 pieces.

The height of the step is found by dividing the height by the number of steps obtained.

You can determine the length of the supporting structure by the Pythagorean theorem, that is, add the square of the height to the square of the length and get the size of the stringer in length.

The reliability of the kosour depends largely on the correctly selected beams when it comes to wood. Only hardwoods will provide the required strength. The workpieces must be sanded. Perfect fit:

  • oak;
  • beech;
  • maple.

    The thickness of the bearing beam depends on the height of the stairs. One requirement applies here: the higher, the thicker.

    The stepped stringer is installed quickly and easily, it is enough to make cutouts in the form of a triangle. The result is a staircase projection.

    The leg of the triangle being cut will be defined as the riser height and tread depth. A ruler in the form of this geometric figure is necessary for marking the beam. According to the established marks, excess places are cut off with a circular saw.

    Wooden stringer is used in most cases from the sides. The only drawback can be considered sawing, since it reduces the thickness of the supporting beam, which negatively affects the strength of the frame as a whole.

    The straight / broken kosour should have a slope of 30-45 degrees, the height of the steps from 15 to 24 cm, and the treads, that is, the indents from the supporting element on the base - 25-32 cm.

    If the support is made of two or three beams, it is worth paying special attention to the ends of the supporting base of the stairs. They should not only be attached to other contacting elements, but also to each other. Such a connection creates a special effort due to which there is no loosening of individual parts during operation.

    The number of beams in the support structure is not always the same. It is influenced by the width of the steps. If the indicator is up to 1.2 meters, then one reinforcement is enough, if higher, but up to 1.5 m, then the staircase structure should be on a double base. Triple is necessary with a foot width of more than 1.5 meters.

    In accordance with building codes, when the staircase is a bulky structure, even with narrow steps, additional reinforcement will be needed. Additional fixation to the wall, ceiling is taken into account, especially in places of fractures.

    The area of ​​contact of the elements on the sides and the height of the rise when calculating the helical stringers as basic values ​​are tied to the opening angle of the step. The reference length is inseparable from the rotation diameter of the structure. Marking is applied strictly in the horizontal plane from the points located in the center and only along the middle line.


    Support ladder beams are produced in a wide variety. You can make a constructive solution with your own hands or see what the specialists offer. Alternatively, you can cut out the running steps. As a result, the option chosen depends on personal preference and capabilities.

    Before making a final decision, it is important to determine whether the staircase will fit in the opening provided for it, only then can installation begin. To do this, you need to draw the line of the second floor on the already calculated value of the staircase. It is at this moment that it becomes clear that the selected type of staircase cannot be installed, you have to resort to changes in the project.

    At the time of operation of the structure, you can easily get a head injury if the proper distance to the floor of the second floor is not provided. In full growth, a person reaches his level already standing on the third step. The distance from the head to the ceiling of the 2nd floor should not be less than 20 centimeters.

    On metal beams: methods of fastening steps

    The options for using metal beams involve different types of fastening. If this is a collapsible structure, then a "glass" is used when a pipe is welded onto the stringer, and a support element with an axis equal to the inner diameter of the pipe is attached to the step.

    High-quality fixation is ensured by using bolts. This will allow you to set the required turn for the step and its height. Unfortunately, the method has one significant drawback - rapid wear during operation. In this case, the rigid fixation benefits in durability.

    Fastening is permissible in the groove. If this is a non-separable structure, then greater stability is achieved due to the fact that the joints are fitted at an angle of 45 degrees. The elements are connected by welding.

    Made of wood: sequence

    The best option for making a wooden staircase is a 2 or 3 support structure. Marking is made on a board or bar, along which trimming is subsequently done.

    In order for the grooves to match exactly, you can attach blanks to each other, then refine the flaws along the entire length. There is another option for aligning the support. For this, overhead elements are prepared, which, after marking, are installed on the beam and checked for compliance with this type of assembly.

    On concrete: varieties

    Formwork is the basis of this type of staircase. It must be made waterproof so that the concrete mixture remains inside the created wooden frame, and does not flow out of it. Reinforcement is laid inside, connected to each other in the form of a mesh, and only concrete is poured onto it.

    To avoid voids, it is worth compacting the cement. For this, a special tool is used, or all the work is done manually. Only after complete solidification can you start decorative finishing. Type-setting steps are manufactured in accordance with GOST.

    Design examples

    The staircase must fit into the created interior in the house, since it sometimes acts as a separate element, taking all the attention to itself. The design of steps, railings is sometimes more expensive than the creation of a structure as a whole.

    • As a basic example, we can recall the classics with numerous decorative elements. These are always complex design projects, especially when it comes to wood. Carvings and curly elements fit perfectly into almost any interior; they often turn out to be the main decoration in themselves.
    • For those who prefer comfort and simplicity, it is worth thinking about the country style in which the staircase can be made. The steps can be made of ceramics or natural stone, artificial aging looks very good. Floral motifs and household items are used as the main decoration.
    • If you like modern minimalism in design, then high-tech style is what you were looking for. It is dominated by a lot of glass, metal and the simplest forms, clear straight lines. Spiral and mid-flight staircases look great in this design. Glass can be used in handrails, steps or decoration elements.

    The choice of material must be started even before the construction work is carried out. It is worth considering the features, individual characteristics, the purpose of the stairs and the age of the residents of the house. Where there are children, special safety requirements are imposed on the structure.

    Today there is no limit to human imagination, it is enough just to understand what exactly you want to see at the end. The unusual shape attracts more and more, sophistication does not lose popularity, but the business style is gaining more attention.

    The advantage of a stringer staircase is that it is perfectly visible. In addition to the functional component, such an element began to carry more and more a decorative load in the overall interior. It has become popular to attach each step to a separate element that sits on the support beam. In this case, if you lay two kosour, you can do without risers. The fastening of the wooden step takes place by means of self-tapping screws, completely invisible and very reliable. If a defect appears over time, then only one structural element requires replacement, the restoration becomes less expensive.

    Metal stringers eliminate squeak when moving. This is because the frame is tough and durable, at the base is a welded rod. Even at high humidity, the metal does not deform, and the frame does not loosen over the years.

    The cost of such a ladder is not much different from a wooden one, but it is possible to achieve a hanging strength. You can use thin boards, since the steps do not experience a bearing load, and therefore perfectly support the required weight.

    To learn how to build a staircase for a terrace on kosoura, see the video below.