Peculiarities of spiral staircase design. Materials used for its construction and rules of calculation. Practical hints on how to build a spiral staircase.
A spiral staircase in many ways excels more conventional flight staircase: fewer means are needed for its construction; it takes less space and is aesthetically pleasing. It is rather important to consider a lot of parameters in its production: the size of winding steps, the width of the tread and configuration of the handrails. Deciding on how to build a spiral staircase, first you should pay attention to some important points.
Nuances of spiral staircase construction
In fact, more convenient in operation spiral staircase is that with a passage width of more than 3 ft. Thus, the diameter of the entire structure including dimensions of the central column is about 7-8 ft.
Less expensive and therefore more popular is a design with the steps fixed to the central column and handrails mounted on balusters. Staircase with bent-glued handrails supporting stairs without a central pillar is more complex option, which is tricky to accomplish.
Spiral structure does not necessarily have to be circular in cross-section: it might be a polygon which sides are adjacent to the walls. Herewith, fastening the steps can be performed directly onto the walls, using the grooves and plates.
Materials for spiral staircase manufacturing
Central column of a metal staircase is a metal tube with a minimal thickness of 4 mm and a diameter of at least 50 mm. The spiral staircase made of wood is usually supplied with a rack in the form of a wooden column. Furthermore, for manufacturing of the central pillar of any type brick, concrete or natural stone can be used.
Handrails can be made of oak glulam or other hardwood and of metal as well. However, materials can be combined. Steps can be metal (thick sheet steel or openwork woven forged rods), wooden and even made of thick tempered glass.
- It is advisable to exclude risers from the structure: this approach allows the feet to step on a stair with a free inner edge. The leg will not slip from such stairs even in the narrowest side of descent (near the column).
- The passage height should allow for free movement: its value should be at least 6-7 ft.
- The column should be mounted in a place that is able to withstand the weight of the entire structure along with a number of people. Its fastening should be tough.
- A few inches overlap of one step over another further strengthens the structure: this is due to the brackets fitted between the front and rear edge of the wider part of adjacent steps.
Calculation of spiral staircase design
The length of the steps depends on the dimensions of the opening in the ceiling. Number of steps is the result of dividing the height of the entire structure to a riser height, taking into account the thickness of one step. The height between the steps must be at least 7-8 inches.
The height of the staircase structure is predetermined by the height of the premises. To measure this value not only roulette should be used, but also a plummet. To make it easier to calculate the total number of steps, you can determine not only their number for a full spiral, but for three quarters (270°) or half (180°). The width of the tread middle must not be less than 8 inches: this is where people step on the stairs most often. The minimum width of the tread at a distance of 6 inches must be equal to at least 4 inches.
How to build a wooden spiral staircase
Sharp edges should necessarily be treated with sandpaper. For the original interior designed in certain colors, the stairs can be painted. However, if it is essential for you to emphasize the naturalness of the material, it will be sufficient to cover stairs with several coats of parquet varnish. Here you should consider that you can apply varnish only after processing wood with stain. After drying the steps are equipped with the sleeves, by means of which they will be fixed to the column.
The next element of spiral stairs is balusters. They can be made of wooden rods or metal bars, or you can buy them ready-made. When making balusters one is to be done a bit larger. It will go to the first step and be installed on the floor. This will enhance the strength of the whole assembly.
It is much harder to cope with the manufacture of handrails. You can install straight beams, but such avant-garde design looks impressive only in the appropriate interior. An embodiment preferred most is the bent structure, although it is quite a labor-intensive option.
The point is that wooden stringers are very difficult to bend. The wood is necessary to mature in boiling water until the material is softened; after that it is bent in the required area. It is not always possible to do it right at once. There is a modern method: gluing thin slats will result in required bend.
Installing a spiral staircase step by step
First, install the supporting column. Next, fasten the first and the utmost treads and the intermediate sleeves. The next stage is distributing the steps circumferentially, orienting by the correct installation of the first and the utmost ones; then the support brackets are mounted.
The utmost step is mounted directly to the soffit. The job is finalized with the installation of balusters and handrail attachment, then the design is ready for operation.