A scaffold (scaffolding) is a temporary structure that gives workers and materials safe access to elevated work. Depending on your region the materials vary, but most scaffolds are built from steel or aluminium tubes, couplers or system connections, and boards or metal decks. Scaffolding is typically modular and is erected, altered and dismantled by specialist scaffold contractors.
Main parts of a scaffold
- Standards – the vertical tubes or posts that carry the load to the ground.
- Ledgers – horizontal members running along the length of the scaffold, joining the standards.
- Transoms (bearers) – horizontal members across the width that support the boards or decks.
- Bracing – diagonal members that keep the scaffold square and stop it swaying.
- Base plates and sole boards (mudsills) – spread the load from each standard onto the ground or slab.
- Platforms – boards or decks forming the working level, with guardrails and toe boards.
- Ties – connections back to the building that stop the scaffold pulling away or falling over.
- Access – ladders, ladder towers or stair towers to reach each lift.
Types of scaffolding
| Type | How it works | Typical use |
|---|---|---|
| Tube and coupler (tube and fitting) | Loose tubes clamped together with couplers, so it can be built to almost any shape | Irregular buildings, industrial plants, heritage facades |
| Frame scaffold | Prefabricated welded end frames joined by cross braces | Masonry, facades and interior work, very common in North America |
| System (modular) scaffold | Standards with rosettes or cups at fixed intervals that lock ledgers and braces in place | Large facades and repetitive work where fast erection matters |
| Mobile (rolling) tower | Frame or aluminium tower on lockable castors | Interior ceilings, MEP rough-in, short tasks that move around |
| Suspended (swing stage) | Platform hung on wire ropes from roof anchors and raised by hoists | High-rise facade work, glazing, caulking, cleaning |
| Cantilever or needle | Supported off the structure on beams instead of from the ground | Where the ground cannot take a scaffold base, such as over a street or roof |
| Birdcage | A grid of standards and ledgers filling a room with a deck at the top | Working on high ceilings over a large floor area |
Scaffold safety and inspection
- Scaffolds should be designed, erected and altered by trained people under a competent supervisor. Anything unusual (tall, heavily loaded, sheeted or cantilevered) normally needs an engineered design.
- In the US, OSHA’s scaffold standard (29 CFR 1926 Subpart L) requires inspection by a competent person before each work shift, and fall protection for workers more than 10 ft above a lower level.
- In the UK, the Work at Height Regulations 2005 require inspection before first use, after alteration or adverse weather, and at intervals of no more than seven days. NASC guidance (TG20) covers tube and fitting scaffolds.
- In Canada, scaffold rules sit in provincial occupational health and safety regulations, so check the province you are working in.
- Many sites use a tag system to show whether a scaffold is safe to use. Never remove ties, braces or boards yourself; ask the scaffolder to adapt it.
- Keep loads within the scaffold’s rated duty and stock materials over the standards, not mid-span.
Related terms
Related templates and guides
- Guide to Scaffolds and Scaffolding
- Guide to Scaffold Inspection and Maintenance
- Mobile Scaffold Inspection Checklist
- Construction Safety Meeting – Scaffold Safety
- Exterior Access in Construction
Frequently asked questions
What is the difference between a scaffold and scaffolding?
They mean the same thing on site. ‘A scaffold’ usually refers to one structure, such as the scaffold on the north elevation, while ‘scaffolding’ refers to the system or the materials collectively. Both describe a temporary structure that provides access and a working platform at height.
What are the OSHA rules for scaffolding?
OSHA’s construction scaffold rules are in 29 CFR 1926 Subpart L. Key points include capacity requirements, guardrails or personal fall arrest for workers more than 10 ft above a lower level, safe access, training, and inspection by a competent person before each shift. Read the standard itself for full requirements.
How often should a scaffold be inspected?
In the US, a competent person inspects before each work shift and after anything that could affect its integrity. In the UK, inspections are required before first use, after alteration or adverse weather, and at least every seven days. Record each inspection on the scaffold tag or register.
Who is allowed to erect or alter a scaffold?
Only trained scaffold erectors working under a competent supervisor. In the UK most scaffolders hold a CISRS card. Other trades should never remove ties, boards or guardrails to suit their work; they should ask the scaffold contractor to make and sign off the change.
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