A staircase can be described as one of several flights of stairs that leads from one floor to another. Construction of concrete stairs has several steps that need skilled labour and a qualified engineer to complete the task. These steps include;
- Preparing foundation
- Constructing formwork
- Placement of reinforcements
- Concreting the stairs
- Finishing and curing
The above-mentioned steps should be studied and designed carefully from the start to the end of construction.
Designing the Concrete Stairs
This is the first step of the concrete staircase construction process. The engineer studies the site and identifies the factors which influence the design. Some of the factors are;
- Height of the floor
- Width of the stairs
- Rises depth
- The thickness of the stairs
- Thread width
- Angel of the proposed stairs
- Load to be applied
Once the details have been identified the engineer now looks at the standard dimension and components of the proposed stairs which are;
- Thread Dimension 9 – 9.25 Inch
- Riser Dimension 7.5 – 8.25 Inch
- Width Dimension 3 feet
- Flight Angle Dimension 30 – 45 degree
The above standard components measurement will give an accurate and perfect staircase.
Preparing Foundation and Support for the Concrete Stairs
The concrete stairs will be supported by a foundation that should be constructed perfectly. This will enable it to transmit the loads to the ground properly and withstand its movement.
If you have a plinth beam present at the beginning of the stairs, it’s advisable to connect them to the reinforcement steel bars to transfer the loads. If there is no plinth beam, a small concrete foundation is constructed. The stairs are supported at the top by the roof beam or slab to restrict the movement.
Constructing Formwork for the Concrete Stairs
A staircase that is constructed without proper formwork will collapse. With this in mind, construct an appropriate formwork by evaluating all the dimensions and angles of the flight, thread and riser.
When constructing a stair that is attached to the wall, it is recommended you mark the line of flight, thread and riser on the wall for easy setting of shuttering.
Concrete is heavy, therefore make sure the boards are at least 2″ thick to carry the concrete weight. The build formwork structure should be supported by 4×4 posts. The steps are constructed using wooden boards which are fastened using screws in the lateral formwork structure.
Placement of reinforcement for Concrete Stairs
Reinforcement is achieved by adding steel bars to the concrete stairs to bear the loads that will be directed to the stairs and transfer them to the ground. An engineer is responsible for calculating the number of steel bars and sizes as per the loads directed to the stairs. The reinforced steel bars should be arranged in the formwork and spacing of 24mm and tied together.
- Concreting the Stairs
Concreting starts from below going upwards. Make sure concrete mix is done properly as it plays a big role in strength and stability. The ratio mix for stairs is 3 parts cement, 2 parts sand and 4 parts gravel and water.
A concrete vibrator is used when pouring the concrete. This helps to fill all the gaps and eliminate honeycomb formations.
Concreting should be done the same day to create a strong bond among the components. Do it carefully to avoid hampering the formwork alignment which can collapse.
- Finishing and Curing
Concrete stairs should be left for 21 days to set. Proper curing should take place in between the 21days to prevent cracks caused by thermal expansion. Then you can remove the formwork carefully without damaging the stairs.
The stairs can be finished as per the owner’s use and requirements. You can use cement tiles, carpet or wood.