Concrete spiral staircases: basic technology and nuances

Concrete spiral staircases combine durability and a contemporary look to create a distinctive and fashionable addition to any building. Spiral stairs, as opposed to conventional straight staircases, conserve space and give your house or place of business a focal point. They are a popular option for architects and designers because of their sleek, winding design, which can be tailored to suit different tastes and styles.

A concrete spiral staircase needs to be built with precision and careful planning. In order to complete the process, a strong framework must be built, concrete must be poured, and each step must be precisely spaced and firmly fastened. Even though the fundamental technology may appear simple, there are a few subtleties to take into account in order to achieve a perfect finish and stability over time.

Building a concrete spiral staircase requires careful attention to detail, from material selection to realizing the value of appropriate reinforcement. This tutorial will lead you through the necessary procedures and offer advice to help you overcome the difficulties involved in creating your own concrete spiral staircase. Having a solid understanding of the fundamentals and the finer points will guarantee success whether you’re an experienced builder or a do-it-yourself enthusiast.

Concrete spiral staircases are a popular option for modern architecture because they combine space-saving features, visual appeal, and durability. This article examines the fundamental technology used to build these staircases, as well as the supplies required and the methodical procedure. It also emphasizes important details, like design considerations and typical problems to look out for, so that even inexperienced builders can produce results that are professional.

Classification

Let’s first examine the potential varieties of concrete stairs before moving on to the benefits and drawbacks.

Traditionally, there are a few forming factors that can be used to divide interfloor structures:

Crucial! Any concrete staircase increases the strength of the structure by supporting and distributing specific weight loads.

Location

The stairs in this instance can be separated into internal and exterior, or street, categories. Why is it crucial to understand the precise application of the structure?

In order to properly choose the concrete grade, consideration must be given to the elements that require resistance to moisture or cold. Additionally, the finishing material and, consequently, the object’s final estimated cost are greatly impacted by the object’s location.

In addition, the direction of load distribution is considered when calculating and designing stairs. External stairs typically have only two support points, which necessitates the construction of a special part of the foundation that takes the expected load into account. This is in contrast to internal structures, which have support points on multiple load-bearing elements of the building and distribute the weight proportionately.

Method of construction

The exact construction of the concrete structure is primarily determined by the design of the building.

Basically, there are two approaches:

1. Standard designs make it possible to assemble from ready-made factory-made reinforced concrete products.
2. Private construction, as well as interesting design solutions, are a priori carried out by pouring concrete into formwork.

Furthermore, the second option has far more possibilities if the first option’s price is more appealing. Since the reinforcement in each case is attached to the building, the strength characteristics remain the same.

Form and design

Stairs are classified as rectilinear or curvilinear based on their shape, specifically:

• Flight structures can consist of one or more spans connected at an angle of 90 or 1800. More common in construction than other forms, as they are simple to construct. Often formed from ready-made blocks. Very durable and economical.
• Spiral staircases made of concrete are in demand in private construction and, as a rule, are arranged inside the building. Design and construction of such a structure requires special construction knowledge and skills. Assembling the formwork in this case is a very complex process. In addition, when installing a spiral staircase, it is necessary to correctly calculate the load level on the walk-through part.

From the perspective of design, spans can be:

• Smooth-beveled. They are easy to identify by the flat (smooth) lower part of the span. Simplicity and elegance of the solution. Nothing superfluous, but at the same time no additional advantages.

• Have a double frame. The lower (back) surface of the flights in this case also has a stepped shape. It looks very original and is a fairly popular design solution. But it is worth considering that in this case the structure gains additional weight.

• Include elements of stringers or bowstrings. Allows you to visually lighten the concrete, make the staircase “airy” and conditionally more transparent. But from the point of view of construction technology, this is the most difficult option.

Why concrete?

The contemporary building material market provides a plethora of options for realizing any concept. What makes a concrete spiral or marching staircase better than alternatives, then?

Let us examine the benefits and drawbacks of cement mortar and, consequently, the characteristics of monolithic steps’ performance.

Pros of a monolith

One of the longest-lasting and most resilient materials is concrete. Any mortar structure will last for decades if the pouring technology is used correctly.

There are historical examples of concrete structures that are hundreds of years old. But what more can concrete steps provide than a long lifespan of use?

Among the benefits that are unqualified are:

• Strengthening of the building structure as a whole. Any monolithic staircase is essentially an additional element of the rigidity of the structure, forming a reinforcing contour.
• High degree of reliability. Reinforced concrete is reinforced with metal reinforcement, due to which the finished block becomes more resistant to stretching. In the case of stairs, when the structure is supported at several points, this factor is quite significant.
• The ability to create steps of complex shaped forms. The solution is fluid and for this reason very plastic, which allows you to create semicircular or concave shapes.
• Fire safety. Concrete is not flammable, but this is not the main thing. Under the influence of high temperatures, concrete does not emit harmful substances and does not collapse, which means that in the event of a fire, the stairs will not collapse and will not become a trap.
• Comfort in operation. Cement steps do not loosen, do not dry out, and therefore do not creak.
• Budget and easy to maintain. Concrete does not require regular renovation or any cosmetic measures and is quite economical in terms of current repair costs.
• A wide range of finishing materials. Almost any material is suitable for facing concrete steps. In this case, everything is limited only by the imagination of the designer and the financial capabilities of future residents.

Be aware that you can set up a very sturdy interfloor transition structure in a small or constrained space with a spiral concrete staircase.

Some disadvantages

• Significant weight. The weight of even a small concrete staircase will exceed 1 ton. Therefore, during construction, the additional load on the foundation should be taken into account.
• High level of labor costs. This is perhaps the most serious disadvantage. Despite the low cost of materials, the amount of time and effort required to install steps in the formwork is quite significant.
• Monumentality. Concrete does not let light through, which means that the room with the stairs will visually decrease in size. It is for this reason that, as a rule, monolithic structures are installed in spacious rooms with high ceilings.
• Mandatory decorative finishing. The porous structure of concrete perfectly absorbs moisture from the air and without proper protection, the monolith will begin to dust and delaminate over time, which will ultimately lead to the formation of cavities and cracks, and a decrease in strength characteristics.

Crucial! The screed will need to be disassembled and a stronger base will need to be poured beneath the stairwell’s support if the intended structural support rests on a screed constructed with foam plastic for thermal insulation.

If a concrete spiral staircase is intended for the device, we will explain below how to minimize the drawbacks and fully utilize the advantages of the material.

Basic technology

Let’s break down the entire building process into multiple primary phases:

1. Calculations and design. Stairs are a high-injury area, so none of them should be built, what is called “on your knees”. To avoid unnecessary expenses, as well as to make the use of the interfloor passage comfortable and safe, it is necessary to accurately calculate the number and size of steps, the width of the flight, taking into account the embedded parts for the railings.
2. Formwork assembly. This stage is the most difficult and labor-intensive. If you are building a spiral staircase from concrete with your own hands, and you do not have the necessary experience and knowledge, then it is better to use a factory set of formwork panels.
3. Bundle and installation of a reinforcing frame made of metal reinforcement. At the same stage, the installation of embedded parts for fences takes place.
4. Pouring mortar into formwork. This process is carried out continuously, so you should take care of the required amount of concrete in advance.
5. Dismantling of removable formwork sheets. You can remove the side panels after 10-14 days, depending on the drying temperature. Final dismantling is carried out after the solution has completely set, that is, after 4 weeks.
6. Decoration. As we have already said, in this case, decorative finishing is not only beauty, but also an additional factor in protecting the monolith.

And now for more information on each step and some expert guidance.

Project

It is preferable to leave the project drafting to experts when dealing with screw monolithic structures. It is impossible to determine how much reinforcement is needed without specialized knowledge, and it is very simple to measure the passage area incorrectly.

When accepting the project in this instance, the only consideration you should have is that:

• The angle of inclination of the flight of stairs should be in the range of 30 – 450. The steeper the angle, the more difficult it will be to move up and down the stairs. This is especially important if there are children or elderly people in the house.
• For a comfortable step, the width of the tread, i.e. the horizontal platform of the step, should be 24 – 30 cm.
• The height of the riser, its vertical part should not exceed 20 cm. In this case, the thickness of the finishing material should be taken into account.
• The number of steps in one flight of stairs should be odd: it is more comfortable to start and finish moving up the stairs with one foot.
• A comfortable height of the handrails is at a distance of about a meter from the tread.
• Passage height. It is important that the distance from the step to the upper floor is at least 2 m.

Use the following formula, which accounts for the average step length of a person, to determine the approximate number and size of steps: 2H + L = 64 cm, where L is the tread depth (horizontal portion of the step) and H is the step height (size of the riser).

Crucial! Remember that not all of the winder steps are used for passage when calculating the flight of stairs’ width.

Installation of formwork

Even for skilled builders, creating homemade prefabricated formwork for a concrete spiral staircase can be highly challenging. Certain prefabricated buildings are available for purchase in stores or rental from building companies.

However, if you are sure of your skills, then to put together the formwork you’ll need:

• moisture-resistant plywood from 20 mm thick for the bottom and side panels;
• 100*100 mm beam for supports;
• 30 mm boards for reinforcement;
• connecting metal corners and self-tapping screws.

Note: Marine plywood is a better option for steps with intricate or semicircular shapes because it is sufficiently strong and flexible.

The following are the installation instructions:

1. cut and saw out the plywood according to the project, exactly to size;
2. mount the bottom sheet on the supports;
3. fasten the side panels with corners and screws.

The assembled formwork needs to remain fixed and unable to move.

Crucial! The entire structure needs to be practically airtight, free of cracks, and exceptionally strong given the weight of the concrete and metal. This means that it needs to be able to support an average of two tons of weight.

Reinforcement with metal

Another step that, without construction experience, is nearly hard to complete on your own in the case of a monolithic spiral staircase.

Here, it’s crucial to take into account the following points:

• The internal reinforcement of the steps must be securely fastened with metal drilled into the load-bearing walls.
• The reinforcement rods must be at least 50 mm from the edge of the concrete fill.
• To distribute the load, the entire area of ​​the steps must be reinforced.
• It is better to connect the longitudinal and transverse rods with a bundle using construction wire, rather than welding.

Pouring the solution

Pouring the concrete won’t be tough if you’ve finished the earlier steps successfully, but there are a few things to keep in mind:

• For the construction of stairs, a solution of at least B15 strength is usually taken.
• Pouring is carried out from the top step.
• As it is filled, the solution should be tapped and vibrated several times to get rid of the air inside.
• The entire pouring is carried out in one step, partial setting of individual sections is not allowed.
• The upper horizontal surface of the steps is leveled before setting.
• After pouring, the entire structure is covered with polyethylene film to retain moisture when the concrete sets.

By viewing the video on this page, you can learn more in-depth details about how to build a spiral concrete staircase on your own.

Dismantling of formwork and decorative finishing

After 10–14 days, 70% of the concrete sets. In order to save time, you can carefully remove the side panels after two weeks and apply a finishing primer to the concrete.

Remove bottom panels and supports no sooner than 28 days after installation. It’s crucial to preserve the integrity of the step edges and prevent chipping the concrete when removing the formwork.

The staircase is prepared for finishing after four weeks. The selection of the ornamental material determines what happens next.

Topic	Details
Foundation	A solid foundation is crucial for stability. Use reinforced concrete to ensure durability and strength.
Formwork	Create a precise formwork to shape the stairs. Use plywood or steel for the formwork to maintain the correct spiral shape.
Reinforcement	Install steel bars within the formwork to reinforce the concrete, enhancing the staircase"s strength and load-bearing capacity.
Pouring Concrete	Pour concrete into the formwork in layers, ensuring each layer is compacted to remove air pockets and achieve a solid structure.
Curing	Allow the concrete to cure properly. This involves keeping the surface moist and protected to reach maximum strength.
Finishing	After curing, remove the formwork and smooth the surface of the stairs. You can add a non-slip finish for safety.

Concrete spiral staircases are a popular option for modern architecture because they combine aesthetic appeal with practicality. You can design an eye-catching, long-lasting staircase that elevates your area by being aware of the fundamental technologies and subtleties involved in their construction.

Precise planning is required for the entire process, from selecting the appropriate materials to guaranteeing precise measurements and appropriate reinforcement. A staircase that is not only aesthetically pleasing but also secure and long-lasting can be achieved by paying attention to these little details.

Although building a concrete spiral staircase might seem difficult, it can be made easier by breaking the process down into smaller, more doable steps. You can produce amazing results that endure over time if you execute carefully and put a strong emphasis on quality.

The durability and appearance of the staircase are further enhanced by embracing the subtleties of concrete work, such as surface finishing and curing time. Whether you are an experienced builder or a do-it-yourselfer, these tips are essential to a job well done.

Video on the topic

Concrete spiral staircases

Spiral staircase from "Best Step Concrete Stairs"

Monolithic concrete stairs