Shorings are classified under the following categories:
- Raking or Inclined shores
- Flying or Horizontal shores
- Dead or Vertical shores
1. Racking or Inclined Shores
In the type of shoring inclined members are adopted to provide temporary support to the external walls from the ground. These inclined members are called as rakers. An inclined shore primarily consists of rakers, braces, wall plate, needles and plank.
The wall plate is fastened to the wall by means of square needles. The needles penetrate into the wall for a depth of about 15 cm and prevent the wall plate from sliding against the wall. The wall plate distributes the pressure evenly (Fig. 22.9). Further the needles in turn are strengthened by providing wooden cleats. The inclined rakers are interconnected by timber braces. The feet of the rakers are tied together by braces and hoop iron. They are in turn connected to sole plate by means of iron dogs or dog spikes.
Figure 22.9 Raking or Inclined shoring of a wall
The details shown in Figure 22.9 is a simple raking shore for a building height of 10 m. For multi-storeyed building and building on road side, special rakers have to be used. While dealing with road side buildings, the bye-laws in force of the locality have to be followed.
2. Flying or Horizontal Shoring
In this type of shoring horizontal supports are provided parallel to the walls which have become unsafe due to some reason (Fig. 22.10). This arrangement is called a simple flying shore.
Figure 22.10 Details of single flying shore
This type of flying shore comprises of wall plate, needles, cleats, struts, straining pieces and folding wedges. As in inclined shores, here also the wall plates are secured against the wall by means of needles and cleats. The horizontal shore is kept in the required position by means of wedges, needles and cleats to the wall plate. The inclined struts are supported by the needles at there one end and straining sill at the other end. In turn the straining is fixed to the horizontal shore.
This type of simple flying shoring can be adopted for a maximum distance of about 9 m between the adjacent parallel walls. When the distance is from 9 to 12 m, a compound or double flying shore, shown in Fig. 22.11, may be provided. It is to be noted that both the horizontal shores are symmetrically placed with respect to floor levels.
Figure 22.11 Details of double flying shore
3. Dead or Vertical Shoring
These shores are placed vertically and are used for the temporarily supporting the wall while the lower part of which are to be removed for repairs. By this arrangement the whole load of the roof is supported by these shores (Fig. 22.12).
Needles are used to transfer the load from the walls. These are first inserted into small wall opening which is made just sufficient to fit. Horizontal beams are laid along the floors. This beam supports the dead or vertical shore and distributes the load evenly on the base. The dead shores are installed in between the beams and the needles by means of wedges. In order to avoid any damage, the usual walls are supported with props before removing the desired portions. In the same way, the windows or other openings are duly strutted.
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