a. When the height of construction is more than 1.5m, workmen need some platform on which he can stand safely, keep necessary materials of construction and carry on the construction etc.
b. These temporary structure or platform constructed very close to the wall, is in the form of timber or steel formwork, commonly called scaffolding.
c. The height of scaffolding goes on increasing as the height of construction increases.
Purpose of construction:
a. Provides a platform to stand safely and carry on the construction.
b. Provides platform to keep necessary materials of construction, tools such as bricks, mortar, trowel, plumb, etc.
c. Scaffolding is also needed for repair or even demolition work of a building.
Component Parts of Scaffolding:
a. Standards: These are vertical members of scaffolding, supported on the ground or drum or embedded into the ground.
b. Ledgers: These are horizontal members, running parallel to the wall and perpendicular to the standards.
c. Braces: These are diagonal members fixed on standards.
d. Putlogs: These members are placed on ledgers at right angles to the walls, with one end supported on ledgers and other end on the wall.
e. Boarding or Planks: These are the horizontal platform for supporting men, materials and appliances, these are supported on putlogs.
f. Guard boards: To guard against the materials, the boards are provided at the working level called guard boards.
g. Toe boards: These are boards placed parallel to the ledgers and used for protection at the level of working platform.
Types of Scaffolding:
a. Single Scaffolding: This consist of a single row of standards (vertical members) which are driven into the ground at a distance of about 1.5m to 2.0m apart and about 1.2m away from the wall to be constructed. Putlogs are placed with one end on the ledgers and other end in the hole left in the wall, at an interval of 1.2m to 1.5m.
b. Double or mason’s scaffolding: The framework is similar to the single scaffolding except two rows of standards are used, one row close to the wall within 15cm of the wall faces and the other at 1.2 to 1.5 m away from the face of the wall. The putlogs are supported at both the ends on ledgers. Rakers and cross braces are provided to make the scaffolding more strong and stable. It is generally used while constructing stone masonry, as it is very difficult to provide holes in the wall to support putlogs. Such a scaffolding is also called independent scaffolding.
c. Ladder Scaffolding or Patented Scaffolding: Ladder scaffolding is modification over a double scaffolding and can be easily assembled. Many patented scaffolding made of steel are available in market. The scaffoldings are equipped with special coupling, frames, etc.
d. Cantilever Scaffolding or needle Scaffolding: This type of scaffolding is provided under following conditions: - Single scaffolding as well as double scaffolding rests at ground level may cause obstruction to traffic on busy street. - If repairs are to be carried out only in few floors at higher elevation in tall building,, then it is uneconomical to provide scaffolding from ground floor.
e. Suspended Scaffolding: This is a light weight scaffolding used for repair works such as pointing, washing, painting, etc. In this type of scaffolding, working platform is suspended from roof by means of ropes and chains. Arrangements are made to raise or lower the platform, so that the work can be carried out at desired level.
f. Trestle Scaffolding: In this type of scaffolding, working platform is supported on the top of movable contrivances such as ladder, tripod stand, etc. mounted on wheel. Such type of scaffolding is generally used for painting and repair works inside the room.
g. Steel Scaffolding: A steel scaffolding is similar to timber scaffolding except that wooden members are replaced by steel tubes and rope lashings are replaced by steel couplets or fittings. Steel Scaffolding has following advantages: - These are simple to erect, as only few fasteners to be dealt with. - It has greater strength, greater durability and high fire resistance. - The scaffolding can be used for form work as well. Hence its versatility increases.