Scaffolding in Building Construction
Scaffold, in Building Construction,
temporary platform used to elevate and support workers and materials during the
construction, repair, or cleaning of a structure or machine; it consists of one
or more planks of convenient size and length, with various methods of support,
depending on the form and use.
In timber scaffolding, support for the planks is provided by a timber
frame fabricated and erected at the site. The frame may consist of vertical
posts, horizontal longitudinal members, called ledgers, transverse members
supported by the ledgers, and longitudinal and transverse cross-bracing. The
planks rest on the transverse members.
Trestle supports are used for work on a
large area if little or no adjustment of height is required (e.g., for
plastering the ceiling of a room). The trestles may be of special design or simply
wooden sawhorses of the type used by carpenters. Specially designed trestles
may be adjusted to provide for working heights of from 7 to 18 feet (2 to 5 m).
Tubular
scaffolding of steel or
aluminum has largely replaced timber scaffolding on most construction projects.
Tubular scaffolding can easily be erected in any shape, length, or height.
Sections may be mounted on casters to provide a highly mobile staging. The
scaffolding may be enclosed with canvas or plastic sheeting for protection
against the weather.
Tubular hoisting towers may be
quickly assembled from steel tubes or
pipes about 3 inches (8 cm) in diameter with standard connections.
A suspended scaffold consists of two horizontal putlogs, short timbers
that support the flooring of the scaffold, each attached to a drum mechanism.
Cables extend from each drum to an outrigger beam attached overhead to the
structure frame. Ratchet devices on the drums provide for raising or lowering
the putlogs between which spanning planks form the working surface. Power
scaffolding may be raised or lowered by means of an electric motor operated by
the worker on the scaffold.
Types of Scaffolding used in Construction:
Following are types of Scaffolding in
construction:
1.
Single scaffolding
2.
Double scaffolding
3.
Cantilever scaffolding
4.
Suspended scaffolding
5.
Trestle scaffolding
6.
Steel scaffolding
7.
Patented scaffolding
1. Single Scaffolding
Single scaffolding is generally used
for brick masonry and is also called as brick layer’s scaffolding. Single
scaffolding consists of standards, ledgers, putlogs etc., which is parallel to
the wall at a distance of about 1.2 m. Distance between the standards is about
2 to 2.5 m. Ledgers connect the standards at vertical interval of 1.2 to 1.5 m.
Putlogs are taken out from the hole left in the wall to one end of the ledgers.
Putlogs are placed at an interval of 1.2 to 1.5 m.
2. Double Scaffolding
Double Scaffolding is generally used
for stone masonry so, it is also called as mason’s scaffolding. In stone walls,
it is hard to make holes in the wall to support putlogs.
So, two rows of
scaffolding is constructed to make it strong. The first row is 20 – 30 cm away
from the wall and the other one is 1m away from the first row. Then putlogs are
placed which are supported by the both frames. To make it more strong rakers
and cross braces are provided. This is also called as independent scaffolding.
3. Cantilever Scaffolding
This a type of scaffolding in which
the standards are supported on series of needles and these needles are taken
out through holes in the wall. This is called single frame type scaffolding. In
the other type needles are strutted inside the floors through the openings and
this is called independent or double frame type scaffolding. Care should be
taken while construction of cantilever scaffolding.
Generally cantilever scaffoldings are
used under conditions such as
o
When the ground does not having the
capacity to support standards,
o
When the Ground near the wall is to
be free from traffic,
o
When upper part of the wall is under
construction.
4. Suspended Scaffolding
In suspended scaffolding, the working
platform is suspended from roofs with the help of wire ropes or chains etc., it
can be raised or lowered to our required level. This type of scaffolding is
used for repair works, pointing, paintings etc..
5. Trestle Scaffolding
In Trestle scaffolding, the working
platform is supported on movable tripods or ladders. This is generally used for
work inside the room, such as paintings, repairs etc., up to a height of 5m.
6. Steel Scaffolding
Steel scaffolding is constructed by
steel tubes which are fixed together by steel couplers or fittings. It is very
easy to construct or dismantle. It has greater strength, greater durability and
higher fire resistance. It is not economical but will give more safety for
workers. So, it is used extensively nowadays.
7. Patented Scaffolding
Patented scaffoldings are made up of
steel but these are equipped with special couplings and frames etc., these are
readymade scaffoldings which are available in the market. In this type of
scaffolding working platform is arranged on brackets which can be adjustable to
our required level.
