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Shoring and Types of ShoringShoring is the means of providing temporary support to attain stability of the structure
under the following circumstances.
(i) To unsafe structures, the stability of which has been endangered due to the unequal
settlement of the foundation, or due to the removal of adjacent buildings, or due to the
defective or bad workmanship, or due to any other reason.
(ii) To structures which might become unstable, when certain alterations are required to be
done in the structure itself (such as re-modelling of walls, etc.) or, during the alterations of
adjacent buildings such as underpinning of (the adjacent building) foundations, dismantling
of adjacent building, etc.
The following points in connection with the installation of shores should be noted.
(i) Temporary support by means of shores to unsafe structures may be given eternally or
intern ally and in certain cases they may be provided from both sides of the wall to produce
additional stability. !ut, before the installation of shores, the necessary permission from thelocal authority should be obtained.
(ii) "horing is used to maintain equilibriums the over-turning forces must be resisted by the
supporting shores. To achieve this, it is essential that the lines of action of the overturning
forces in floors and roofs, the forces in walls and the reaction of the shores must meet at a
single point.
(iii) "horing may be made of timber but for resisting heavy loads, it may be built of steel
tubes, suitably braced steel sections or a combination of timber and steel tubes. #hatever
material is used, shoring should be strong enough to resist the acting forces, consistent with
economy.(iv) This temporary shoring should be provided to unsafe structures till such times as they
have been made stable.
Types of Shoring:
"horing are classified into the following three classes either on the basis of their supporting
characteristics or their position in the space$
%. &aking or 'nclined "hores
.lying or *ori+ontal "hores
. ead or vertical shores.
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&aking "hores
Raking shoresis a system of giving temporary support to an unsafe wall. The
construction of raking shores, also known asinclined shore, varies with the conditions
of site. 'n all cases wall-plate cm. cm. to cm. /0 cm. it si+e is fied against the
unsafe wall with hooks. The wall-plate is further secured to the wall by means of needles.
The needles which are %1 cm. x /0 cm. in section penetrate inside the wall for a distance of
about %1 cm 'n turn, the needles are strengthened by providing wooden cleats. The top end
of the inclined rakers rest against the needles. 2t their base the rakers are supported by a
sole piece bedded in an inclined position in the ground. The rakers are secured to the sole
piece by cleats and dogs. 'n soft ground the area of the sole piece is increased so as to
distribute the pressure over large area. 'n places where more rakers are provided, they are
bound together by means of hoop iron or braces 25 cm. thick and % cm.wide. The
inclination of the outer raker to the ground should vary between 01 to 75. The sets of
shores should be usually placed at to 3.0 m. centre to centre along the wall length.
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lying "hores
Flying shores are hori+ontal supports that are provided for supporting temporarily the
parallel walls of the two adjacent buildings, which may tend to collapse or damage when one
of the intermediate buildings has to be pulled down and rebuilt . "uch conditions
occasionally arise when one of the intermediate buildings from a series of buildings
standing side by side is either required to be reconstructed or has collapsed due to some
reason.
2 single flying shoresconsists of wall plates, struts, straining pieces, hori+ontal shore (or,
hori+ontal strut), needles, cleats and wedges, as shown in the above image. 4ike raking
shores, in this system also, the wall plates are secured against the walls by means of
needles and cleats. Theflying shoresis held in position by wedges, needles and cleats to the
wall plate as shown at section 5 in the image. The inclined struts are supported by the
needles at their one end and straining sill at the other end. "training sill, in turn, is spiked to
the hori+ontal shore.
(i) uring reconstruction of the intermediate building, the flying shorestemporarily take
up the position of the dismantled building.
(ii) The centre-lines offlying shores and struts6 and flying shores and walls, should meet atthe floor levels. 'f the floor levels of two buildings are different or their strengths are
different, then shore positions should be provided as shown in the below image .
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(iii) The maimum distance of about %1 metre between the parallel walls can be supported
by single flying shores. or a distance more than %1 m, a double flying shore, having a
trussed form work as shown in the below image, is employed.
(iv) The flying shores are kept in position so long as the adjacent buildings are made stable
by constructing the building to a sufficient height.
(v) 7nlike the inclined shoring in this type, only one set of shoring is employed to
strengthen the two adjacentwalls.
(vi)2 larger factor of safety should be adopted in design analysis of flying shores because of
uncertainty of actual loads. or shores to be more effective, the struts should be inclined at
38, if possible.
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ead or 9ertical "hores
'n this system of shoring, the vertical members known as dead shores are used to support
temporarily the walls, roofs, floors, etc., by providing horizontal membersknown
as needles, to meet one or more of the following objectives$
(i) To rebuild the lower part of a defective load bearing wall6 or
(ii) To rebuild (or replace) or deepen the eisting foundations, which have either become
unsafe or require strengthening for carrying heavier loads6 or
(iii) To provide large openings in the eisting walls such as doors, windows, shop fronts or
garages at a lower level.
'n the above image, the arrangement is shown to meet first two objectives. 'n this system,wooden needles consisting of thick sections are used to transfer the overhead loads to the
properly braced vertical shores. These vertical or dead shores, in turn, transfer those loads
to the ground on firm foundations below. The other details regarding introducing of rolled
steel joists for supporting, strutting of floors by props, use of wedges, sole pieces, are self-
eplanatory.
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'n the below image, the arrangement is shown to meet the third objective, i.e., providing a
large opening in an eisting wall. To meet this objective following procedure is adopted,
(i) !efore providing dead shores to a building, all door and window openings are properly
strutted to resist any possible deformation, and then inside floors of the building are also
strutted by props or vertical posts. 2t the top and bottom of these vertical struts or posts,
timber heads and sole pieces are provided to distribute the load more effectively, wedges are
also used at the bottom or foot of prop for tightening purpose.
(ii) *oles are than cut in the wall by crow bar at points above the required opening, at a
distance of % to . m depending upon the weight of structure above.
(iii) Through these holes, timber or steel hori+ontal beams, called needles, are inserted and
projected at right angles on each side of the wall. ("ee in above image). The projected endsof needle beams are supported on heavy transfer the loads to the ground and hence are
made to rest on a sole plate, firmly bedded on the ground.
(iv) The shores are removed only after the new constructionwork has attained sufficient
strength and this period of removal usually is not less than / days.
(v) The sequence of removal of shoring system should be needles first and then strutting
from openings and floor strutting inside the building.
"ometimes, raking shores are provided to support the wall from above the proposed
opening to safeguard against shocks and vibrations during wall cutting. 'f raking shores are
used, they should be removed after the whole dead shores system is removed.
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