Last reviewed 16 Sept 2026 · 11 min read
Scaffolding
Scaffolding is a temporary structure erected to provide working platforms for workers and materials at heights during construction, repair, painting and maintenance.
Components
| Component | Description |
|---|---|
| Standards | Vertical members (poles/tubes) supporting the scaffold, placed on base plates/sole plates |
| Ledgers | Horizontal members running parallel to the wall, connecting standards |
| Putlogs | Transverse horizontal members resting on ledgers at one end and inserted into holes (putlog holes) in the wall at the other |
| Transoms | Transverse members resting on ledgers of both rows of standards (in independent/double scaffolds) |
| Braces | Diagonal members fixed across standards for stiffness and stability |
| Boards (working platform) | Timber or steel planks laid on putlogs/transoms |
| Guard rails and toe boards | Edge protection against falls of persons and materials |
| Base plates / sole plates | Spread load of standards on the ground |
| Couplers (clamps) | Right-angle, swivel, putlog and sleeve couplers joining steel tubes |
| Ties | Connect the scaffold to the building for stability |
| Bridle | Member bridging a window/door opening to support putlogs |
| Rakers | Inclined supports |
Types of scaffolding
| Type | Description | Use |
|---|---|---|
| Single (bricklayer's / putlog) scaffold | One row of standards parallel to the wall (commonly about 1.2 m away); putlogs rest on ledgers and in holes in the wall | Brick masonry construction |
| Double (mason's / independent) scaffold | Two rows of standards, one near the wall and one away; transoms span between ledgers — no support from the wall | Stone masonry (holes in stone walls are difficult), independent support |
| Cantilever (needle) scaffold | Standards supported on needles projecting through openings from inside the building | When the ground is not suitable or free for standards (traffic, busy streets), upper parts of tall buildings |
| Suspended (swinging) scaffold | Working platform suspended by ropes/chains from the roof and raised or lowered by winches | Painting, cleaning, repairs, glazing of tall buildings |
| Trestle scaffold | Platform on movable trestles or ladders | Interior work at small heights (painting, plastering ceilings) |
| Steel tubular scaffold | Steel tubes and couplers | Quick erection, strong, fire resistant, reusable — modern construction |
| System scaffolds (cuplock, ringlock) | Prefabricated standards with node connections for ledgers | Rapid assembly, formwork support, industrial work |
| Bamboo scaffold | Bamboo poles lashed with coir ropes | Traditional, economical in India and Asia; requires careful inspection |
| Mobile tower scaffold | Wheeled aluminium/steel tower with locking castors | Light maintenance and services work |
| Patented scaffolds | Proprietary brackets and frames | Special applications |
Safety of scaffolds
- Erected, altered and dismantled by trained persons and inspected before use and after bad weather.
- Firm base — base plates and sole plates on compacted ground; no loose bricks as supports.
- Adequate bracing and ties to the structure.
- Working platforms fully boarded, of adequate width, with guard rails (commonly about 1 m high), intermediate rails and toe boards.
- Safe access by ladders or stair towers; ladders secured and extending above platforms.
- Do not overload platforms; keep materials evenly distributed.
- Use safety harnesses where edge protection is incomplete; keep clear of overhead power lines.
Formwork (shuttering)
Formwork is the temporary (or permanent) mould into which fresh concrete is placed and in which it is supported until it gains enough strength to support itself. The term centering is used for supports of slabs, beams and arches, and shuttering for vertical faces.
Requirements of good formwork
- Strong — to carry the weight of wet concrete, reinforcement, workers, equipment and impact loads.
- Rigid — minimal deflection so that concrete members retain their shape and dimensions.
- Watertight joints — to prevent leakage of cement slurry (which causes honeycombing).
- Smooth inner surface for the desired finish; release agents to prevent adhesion.
- Accurate in shape, size, line and level.
- Easy to erect and strip without damaging the concrete; allow removal of sides before soffits.
- Reusable many times; light but durable.
- Economical — formwork is a significant part of the cost of RCC work.
- Supported on a firm base with adequate bracing against lateral forces.
Materials
| Material | Features |
|---|---|
| Timber (planks, battens, joists) | Easy to cut and fix, light; limited reuse, absorbs water, warps |
| Plywood (shuttering / film-faced ply) | Large smooth panels, good finish, more reuses than planks |
| Steel (panels, props, spans) | Strong, rigid, many reuses, smooth finish; heavy, costly initially, needs release agents and care against rust |
| Aluminium | Light, many reuses — system formwork for repetitive housing |
| Plastic / FRP | Light, many reuses, special shapes (waffle moulds, column forms) |
| Fabric and cardboard (sonotubes) | Circular columns, special shapes |
| Permanent (stay-in-place) formwork | Profiled steel decking, precast planks, EPS insulated concrete forms |
Components
Sheathing (surface in contact with concrete), joists/battens and ledgers/runners (support sheathing), props (posts) — adjustable steel props or timber posts — bracing, wedges (levelling and easy stripping), ties (through-bolts, snap ties for wall forms), spacers, yokes/column clamps, head trees, sole plates, form release agents (mould oil).
Formwork for different members
| Member | Arrangement |
|---|---|
| Foundations/footings | Side boards held by stakes and cleats; for pedestals, box forms |
| Columns | Four side panels held by yokes or column clamps, spaced closer near the bottom (higher concrete pressure); cleaning/inspection opening at the base; plumb and braced |
| Beams | Bottom (soffit) board on head trees supported by props, and side boards held by cleats and struts; sides removed earlier than soffit |
| Slabs | Decking (plywood/steel panels) on joists and ledgers supported by props, braced |
| Walls | Panels on both faces held apart by spacers and tied with through-ties, braced with walers and push–pull props |
| Stairs | Inclined soffit decking with riser boards and side boards (stringers) |
Special formwork systems
| System | Description / use |
|---|---|
| Slip form | Formwork raised continuously by jacks while concrete is placed (no joints) — chimneys, silos, cooling towers, lift cores, bridge piers |
| Jump (climbing) form | Formwork lifted in stages (jumps) after each lift of concrete gains strength — high-rise cores, tall piers |
| Table (flying) form | Large pre-assembled slab formwork tables moved by crane from floor to floor — repetitive slab construction |
| Tunnel form | Room-sized steel forms casting walls and slabs together — mass housing, hotels |
| Aluminium panel systems (monolithic construction) | Light aluminium wall and slab panels for rapid cycle times — mass housing |
| Waffle / ribbed slab moulds | Plastic or FRP pans forming ribbed slabs |
| Travelling forms | Tunnel linings, culverts, bridge decks (form travellers for balanced cantilevers) |
| Permanent formwork | Composite steel decks, precast planks, ICF — remain part of the structure |