SCAFFOLDING, SHORING, UNDER PINNING

• When height above floor level exceeds 1.5 m a temporary structure is erected for a safe working platform for worker and space for materials 

TERMS 

1. STANDARDS : vertical members of framework, supported on the ground 

2. LEDGERS : horizontal members // to the wall 

3. PUTLOGS : transverse members, one side supported on ledgers & other on wall 

4. TRANSOM : both the edges are supported on ledgers 

5. BRACES : diagonal pieces fixed on standards 

6. BRIDLE : a piece used to bridge an opening to walls and support putlog 

7. GUARD RAIL : rail parallel to ledgers at working level for safety 

8. TOE BOARD : board placed // to ledger & supported by putlogs 

9. RAKERS : inclined support 

TYPES OF SCAFFOLDINGS 

1. SINGLE / PUTLOG / BRICKLAYER SCAFFOLDING 

• Most common type 

• Mostly used in brickwork 

• Spacing b/w standards : 2 - 2.5 m 

• Vertical distance b/w ledgers : 1.2 - 1.8 m 

• Horizontal distance b/w putlog : 1.2 - 1.8 m 

2. DOUBLE / INDEPENDENT / MASONS SCAFFOLDING 

• Commonly used for stonework 

• Standards is at 20 - 30 cm from the wall 

• Distance between 2 rows of standards : 1 m 

3. CANTILEVER / NEEDLE SCAFFOLDING 

• Used when theres no hard ground for the standards to rest 

4. SUSPENDED SCAFFOLDING 

• Working platform suspended from the roof 

• Used for repair works 

5. TRESTLE SCAFFOLDING 

• Can be used upto a max height of 5 m 

• Working platform supported on movable device 

• Used for maintenance 

6. STEEL SCAFFOLDING 

• Steel tubes of dia 40 - 50 mm, thickness 5 mm are used 

• Durable, fire resistant 

• Hugh scrap value 

• Easy to erect and dismantle 

• Can be constructed to any heights 

• Expensive 

7. PATENTED SCAFFOLDING / LADDER SCAFFOLDING 

• Modified double scaffolding 

• Made up of steel 

• Working platform supported on brackets Needle / cantilever scaffolding 

SHORING 

• Temporary support to structures 

• Adjacent structure is to be dismantled 

• Defective walls to be dismantled 

• Large openings have to be made in wall 

TYPES 

1. RAKING / INCLINED SHORING 

• Needle is penetrated to the wall 150 mm 

• Inclination of rakers 45* - 75* 

• Inclined supports are given to external walls from the ground 

• Rider rakers are used in order to reduce the length of rakers 

• Large factor of safety is used in design 

2. FLYING / HORIZONTAL SHORING 

• When distance between wall is 9 m : single flying shore is used 

• When distance between wall is 9 - 12 m : double flying shore is used 

• Inclination of the strut 45* - 60* 

• Depth of fly shore : 1/30 clear span 

• Width of fly shore : 1/50 clear span 

3. DEAD / VERTICAL SHORE 

• Horizontal member needle 

• Vertical member dead shore 

• Needle is supported by dead shore 

• Used when lower part of the wall us defective 

UNDER PINNING 

• Placing new foundation over an existing foundation, 

• strengthening the existing foundations 

METHODS 

1. PIT METHOD 

• One section excavated at a time 

• If wall length long underpinning starts from center and extend to ends 

2. PILE METHOD 

• Needle act as pile cap 

• Used in water logged areas 

3. CEMENT GROUTING 

• Holes are made and grout is filled with pressure 

4. CHEMICAL CONSOLIDATION 

• An inclined pipe is driven under footing 

• sodium silicate with water is injected