Stone stairs are heavy and need substantial supports. They are preferred for outside stairs and for threshold, approach to basements, heating chambers, etc. Due to regular use, the steps become slippery and dangerous.
Stones are in general hard, durable and weather resistant. They are widely used at places where ashlar stones are readily available. Different types of stone steps adopted are as follows:
- Rectangular steps
- Spandril steps
- Built-up steps
Rectangular Steps
Typical rectangular steps are shown in Fig. 21.10.
Figure 21.10 Typical rebated stone steps
In rectangular steps, the lower edge of one step is supported on the top back edge of the other. In order to strengthen the joint, rebated or checked joints are used. To provide a better appearance, the front edges have moulded noses.
2. Spandril Stone Steps
Here the steps are cut so as to provide a plain soffit. In general, these steps are nearly triangular in shape except at the ends which are built into the wall. This arrangement is used where the headroom is desired. The soffit affords a nice appearance and the weight of steps is also reduced.
Figure 21.11 shows spandrel steps with different soffit arrangements.
Figure 21.11 Spandril steps with different soffit arrangements
3. Built-up Steps
In built-up steps, the tread and riser of each step are made of thin swan slabs similar to timber steps. The stone slab treads and risers are connected by dowels. In case the treads are supported at the ends only, then the thickness of the tread should be more than 5 cm. The stone slabs are placed over concrete or brick steps. This type of steps will give an ornamental look where granite or marble stones are used. Figure 21.12 shows a built up steps at an entrance.
Figure 21.12 Built-up step at entrance
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