Construction of concrete stairs, part 2
An example of calculating a flight of stairs
The total height of the storey is 234 cm. If the stairs are to have 13 degrees, then each step will have a height 234:13 = 18 cm. The width of the footrest is 64 – 2 x 18 = 28 cm.
This results in the horizontally measured length of the flight of stairs: 28 x 12 = 336 cm (when calculating, we take the number of degrees reduced by 1, because the last step is the landing). The illustration above shows a proposed concrete staircase formwork. The structure should be properly adapted to the conditions on the construction site. The drawing and description do not guarantee the stability of the stairs. If in doubt, consult a specialist (engineer, construction technician or foreman). If there is a sidewall, so, as in the picture, first mark all the steps on the wall. If it turns out when selecting, that the calculated dimensions are correct and that the stairs are matched according to the drawing of the formwork panels, of beams and boards we build formwork. A solid structure must be made, otherwise, when filling with concrete, everything may collapse.
Reinforcement
So that the concrete maintains its load-bearing capacity, steel reinforcement should be placed in it. For this, reinforcing steel with a diameter is used 8-12 mm. We cut the steel bars to the required length and arrange them along the course of the stairs. Place the steel bars in the direction of the flight of stairs with an interval of every 10 cm. The bars arranged along and across are connected with each other with binding wire, so that they do not shift when laying concrete. Concrete spacers, placed between steel bars, don't let that happen, so that the bars lie directly on the formwork. We place the reinforcing steel like this, that it is everywhere covered with a layer of concrete with a thickness of at least 3 cm. When the reinforcement is laid, we clean the formwork boards.
Concreting the stairs
Dense concrete of strength class B15 is used to concret entire stairs in one working cycle. Concrete should be brought in from the concrete plant. Then, by tamping, it should be carefully compacted between the elements of reinforcing steel. We also fill individual steps with concrete, compact and rub with a wooden trowel and a smoothing trowel. The steps must have an even and as smooth surface as possible, so that you do not have to put them on again afterwards. Po 30 days we can strip the stairs and load them.
