Scaffolding Definition –
Any temporary elevated platform (supported or suspended) and its supporting structure (including points of anchorage), used for supporting employees or materials or both. There is a limit to the safe working height at which a worker can access the building work from ground level.
Scaffolding is used on new-build projects and for work to existing structures, including maintenance and repair work. The temporary structure needs to be structurally safe yet also capable of rapid erection, disassembly, and reuse.
Functional Requirements
- Provide a safe working horizontal platform
- Provide safe horizontal and vertical access to buildings
Scaffold may be owned and maintained by a contractor, although it is more common for the scaffolding to be hired from a scaffolding subcontractor as and when required. Temporary structures must be designed to suit their purpose by a competent person (e.g. certified structural engineer)
A competent person must inspect the whole of the scaffolding and associated temporary supports, including the tying in and sections that are welded, bolted, and fabricated off-site, prior to use. The inspection must be recorded in the site log. Subsequently, the structure must be checked on a regular basis to ensure it remains safe throughout its use.
Scaffolding and temporary works should always be checked before use following extreme weather conditions,e.g. strong winds.
Scaffold Components
The scaffold is usually constructed from aluminium or steel tubes and clips, with timber or metal scaffold planks used to form a secure and level working platform. Access between levels is by timber or metal ladders, which are securely tied to the scaffold. Other common components are scaffold boards and edge protection.
Scaffold Boards
A standard scaffold board is 225mm wide by 38mm thick with a maximum span of 1.5m. The board is made from sawn softwood. Lightweight metal scaffold boards are used in some systems. Greater spans can be achieved by using thicker boards; the distances between transoms on which the scaffolding boards span must not exceed the maximum span allowed for each board.
Each board must be closely butted together so that there is no chance of the board slipping off the supporting tubes. Each board must overhang the ledger by 50mm, but the overhang must not exceed four times the thickness of each scaffolding board.
| Thickness of scaffold | Max Span between Bearer/Ledger | Min overhead from Bearer | Min overhead from Bearer |
| 32 | 1000 | 50 | 128 |
| 38 | 1500 | 50 | 152 |
| 50 | 2600 | 50 | 200 |
| 63 | 3200 | 50 | 252 |
Scaffolding boards are butted together to make a working platform; the minimum working platform depth is three boards. When materials are loaded onto the platform, the clear passage for workers should be at least 430mm. If the materials are to be maneuvered on the scaffold, a distance of 600mm clear pedestrian passage must be maintained at all times.
When laying bricks, the scaffold platform should be at least five boards wide (1150mm). Hop-up brackets may be used to increase the working height of the lift and to increase the working width of the scaffolding platform. When using hop-up brackets, care must be taken not to overload the scaffold. The cantilevered bracket induces bending moments in the standards.
Toe-Boards
Toeboards must be used at the end of the scaffolding to ensure that materials and tools do not fall off the scaffold. The toe boards must be a minimum height of 150mm. A standard toeboard shall be 4 inches nominal in vertical height from its top edge to the level of the floor, platform, runway, or ramp. It shall be securely fastened in place and with not more than 1/4-inch clearance above floor level. The boards also prevent the possibility of people slipping off the edge of the platform. Toeboards may be removed to allow access for materials and workers but must be replaced immediately afterward.
SCAFFOLD TYPES –
Put log Scaffolds
Putlog scaffolds are erected as the external wall is constructed. The scaffolding uses the external wall as part of the support system . Standards and ledgers are tied to the putlogs. Each putlog has one flat end that rests on the bed or perpendicular joints in the brick or blockwork.
The blade end of the putlog is usually placed horizontally and inserted fully into the brickwork joint, ensuring a full bearing is achieved. Where putlog scaffolds are used on refurbishment work, joints may be raked out to insert the blade end. In such works the blade may also be placed vertically. Where the putlog scaffold is used in new works, the putlog is placed on the wall at the required lift height and the wall is constructed around the blade end of the putlog.
Independent Scaffolding
These scaffolds are erected ‘independently’ of the building structure, unlike putlog scaffolds, and are tied to the structure through window openings. Ties are required to ensure horizontal stability is maintained.
Independent scaffolds are constructed from two parallel rows of standards tied by transoms, which bridge the width of the scaffold, and ledgers, which run along the length of the scaffold. A space is usually maintained between the scaffold and the building to allow the masonry to progress unhindered by the scaffold.
The gap allows the brickwork to be checked for plumb and also helps to reduce damage to the brickwork caused by mortar snots splashing off the scaffold and onto the wall. On long stretches of scaffold, continuous diagonal tubes can be used to run from the top to the bottom of the scaffold structure. These act as facade bracing. Bracing is used to resist horizontal loads and to stiffen the structure.
Proprietary Scaffold Systems
Proprietary systems are another type of independent scaffold. It rely on the same principles as independent scaffold but use standard lengths for ledgers, transoms and standards, all of which are capable of being clipped together and dismantled easily and quickly.
The standards often come with spigot ends, which allow the next standard to be located over the locating spigot very quickly. The jointing systems vary depending on the manufacturer. Proprietary systems rely on ledgers and transoms having a locating lug or bracket fixed to each end; these ends can be quickly dropped into the clips, sockets or cups, which are fixed at regular intervals on the standards.
Components, such as ledgers and transoms, are designed so that they can be interchangeable.
Basic Scaffolding Awareness
All scaffolding should display either a red tag or a green tag.
Red Tag – Unsafe for use
- Do Not Use
- Normally used during scaffold erection/dismantling or whilst waiting for inspection or failed inspection
- Only work allowed on a scaffold with a red tag is erection/dismantling by TRAINED SCAFFOLD ERECTORS
Green Tag – Safe for use
- Signed by scaffold erection supervisor.
- Means the scaffold is safe to use but only valid for 7 days. Then must be re inspected.
- Tag should be placed near to the ladder going up from the ground level
- Tag will also indicate weight limit (low, medium, heavy duty)
User Responsibility
- Before going on a scaffold you MUST check it has a green tag and it has been signed within the last 7 days
- Visual check – No damage, no obvious signs that scaffolding has being changed or altered.
- Working on a scaffold WITHOUT a valid green tag is a serious safety offence
- Only use ladder for access / egress, climbing on framework is prohibited.
- Do not carry equipment up ladders in hands, always tool belt or bag otherwise use rope with bag/box to lift tools and equipment. (both hands are required for climbing)
- To prevent dropped objects, housekeeping at height must be ensured at all times, tools and equipment needs to be kept in bags/containers to prevent from falling.
- Do not lean out of handrail
- Do not stand on scaffold handrails
- IN high wind, heavy rain or fog, the supervisor will make a decision as to if it is safe for work to continue.
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