Types of Scaffolding: A Complete Guide Based on TG20:21

You’ll find eight core scaffolding types that comply with TG20:21 standards: independent scaffolding, putlog (tied) scaffolding, loading bays (with and without beams), ladder access towers, free-standing towers, mobile towers, birdcages, and chimney stack scaffolding.

Each of these systems is designed to meet stringent safety regulations, structural tolerances, and load-bearing limits.

Understanding the differences between them is essential for choosing the right scaffold for your construction or maintenance project, whether you’re working at height on a façade, loading heavy materials, or accessing hard-to-reach areas.

Note: While TG20:21 covers many common scaffolding structures, it doesn’t include all types. Other scaffolds, such as stair towers, gantries, system scaffolding, temporary roofs and hanging scaffolds, may require bespoke design or manufacturer-specific guidance.

Types of Scaffolding – Band Of Brothers Scaffolding’s Quick Take

There are several types of scaffolding used in construction. Common TG20:21 types include independent scaffolding, loading bays, mobile towers, birdcages, and chimney stack scaffolds.

Key Takeaways

• Independent scaffolding features parallel standards tied to structures and supports loads up to 3.0kN/m², with required façade and ledger bracing.
• Loading bays are available with or without beams and can handle up to 10.0kN/m², ideal for storing and lifting materials safely.
• Ladder access towers enable vertical movement and must be ledger braced and securely tied to the main scaffold structure.
• Free-standing towers do not rely on external ties and must follow strict height-to-base ratios depending on indoor or outdoor use.
• Mobile towers include swivel castors for easy movement and require full bracing and compliance with TG20:21 stability rules.
• Birdcages are internal or external scaffolds with a grid-like structure, offering safe access for overhead work and requiring bracing in all directions.
• Chimney stack scaffolding provides access at roof level and must be supported by towers or buttressed with rakers, with plan bracing and load limits in place.

What Is Scaffolding?

Scaffolding is a temporary structure built from tubes, fittings, or modular systems to provide safe access and working platforms at height. It allows workers to carry out construction, maintenance, or inspection tasks securely while storing tools and materials within reach.

In the UK, scaffolding must comply with TG20:21 guidance (for tube-and-fitting scaffolds) and HSE regulations, ensuring correct loading limits, bracing, and safe access are in place. Different scaffold configurations are selected based on project needs, such as façade work, roof repairs, or internal fit-outs.

Once the work is complete, the scaffold is dismantled, making it a flexible and cost-effective solution for temporary access across a wide range of construction and maintenance projects.

Types of Scaffolding in TG20:21

The TG20:21 Operational Guide sets out standardised designs for tube-and-fitting scaffolding that can be erected without bespoke calculations.

It covers the primary scaffold configurations you’ll encounter on UK construction sites, including independent scaffolding, loading bays (with and without beams), ladder access towers, free-standing towers, mobile towers, birdcages, chimney stack scaffolds, and putlog scaffolding.

Each configuration must comply with TG20 parameters for bay sizes, lift heights, tie spacing, bracing patterns, and load classes (ranging from 0.75kN/m² for light access to 3.0kN/m² for heavy-duty use).

If your scaffold setup falls outside these parameters, such as when using sheeting, netting, unusual shapes, or higher loads, then a bespoke scaffold design by a competent engineer is required.

Independent Scaffolding

Independent scaffolding is one of the most common façade access systems in UK construction. It consists of two parallel rows of standards erected alongside a building and securely tied or butted to the structure for lateral stability.

According to TG20:21, independent scaffolds can be built to load classes ranging from 0.75kN/m² (light-duty access) up to 3.0kN/m² (heavy-duty masonry work). This makes them suitable for a wide variety of construction and maintenance tasks.

Key compliance requirements include:

• Façade bracing up to the top lift at every elevation, with one set per six bays.
• Ledger bracing at alternate standards on every lift.
• Guardrails: double at boarded lifts, single at unboarded lifts, and triple at the top lift when required.

As a versatile and adaptable scaffold, independent scaffolding remains the go-to solution for façade work, providing safe and efficient access across multiple lifts while maintaining TG20:21 compliance.

Loading Bays

Under TG20:21, loading bays can be built in two ways: with beams or without beams. Both configurations are designed to safely handle heavy materials and require strict compliance with tie spacing, bracing, and coupler requirements.

• Beam-supported loading bays use steel ladder beams (305mm deep) or TG20-approved aluminium lattice beams. This setup allows greater bay widths and can carry loads up to 10.0kN/m², making it ideal for storing pallets of bricks, blocks, or heavy materials.
• Loading bays without beams rely on shorter bay lengths for stability but can still support two evenly distributed pallets up to 15kN each, provided all TG20 bracing and spacing requirements are met.

Loading Bay with Beams

A beam-supported loading bay is a specialist scaffold for heavy material storage and handling. It uses steel ladder beams or aluminium lattice beams to span the tower and distribute loads safely.

Key TG20:21 requirements include:

• Beams at each line of standards (3 beams for 6+2 board towers, 4 beams for 10-board configurations).
• Structural limits: maximum bay length of 2.0m (Class 3) or 1.8m (Class 4), and maximum lift height of 2.0m.
• Lacing tubes and supplementary couplers required at top and bottom chords to prevent distortion.
• Plan bracing in each bay, plus section bracing between beams, to maintain stability.

This configuration provides robust load-bearing capacity while staying TG20-compliant.

Loading Bay without Beams

A TG20-compliant non-beamed loading bay is constructed using four 0.9m bays to create a maximum length of 3.6m. This simpler setup is often chosen where beam use is impractical but significant load capacity is still required.

Key TG20:21 requirements include:

• Board-bearing transoms at 300mm maximum spacing.
• Standards aligned with the access scaffold, ensuring equal distribution of weight.
• Plan bracing beneath the loading platform for stability.
• Class B right-angle couplers to connect ledgers to standards, with supplementary couplers if no structural transoms are present.

Even without beams, this type of loading bay can safely handle heavy materials if erected and tied in full accordance with TG20:21 compliance sheets.

Ladder Access Towers

Ladder access towers provide safe vertical movement between scaffold lifts and must be constructed as integral parts of an independent scaffolding system. These towers ensure secure access without relying on external ladders, reducing fall risks and improving compliance.

According to TG20:21, key requirements include:

• Ledger bracing at every lift.
• Wing bracing at alternate tied lifts, including the top lift.
• Towers must be tied back using tie tubes at the outer, middle, and inner standards, connected with right-angle couplers.
• Higher-duty ties may be required where towers are exposed to wind or clad with sheeting/netting.
• Maximum heights and tie patterns must always be checked against the relevant TG20 compliance sheet, as these vary with load class and site conditions.

Ladder access towers are essential for safe, controlled access across multiple lifts, but must always be erected strictly in line with TG20 guidance to guarantee structural integrity and worker safety.

Free Standing Towers

Free-standing towers are scaffold structures erected without ties to adjacent buildings or structures, making stability their most critical safety factor. To remain TG20:21 compliant, these towers must meet strict design limits.

Key requirements include:

• Height-to-base ratios: maximum 4:1 indoors (not exposed to wind) or 3:1 outdoors.
• Loading: only one lift may be fully loaded.
• Lift height: maximum of 2.0m.
• Base width: minimum 1.2m.
• Bracing: towers must be braced on all faces with plan bracing at alternate lifts, including the top lift.
• Connections: end transoms must be secured using right-angle couplers.

For external free-standing towers, additional requirements apply:

• A Wind Management System must be in place.
• Towers must be dismantled or stabilised if gusts exceed 40mph.
• At least two lifts must be boarded to reduce overturning risks.
• Cladding or debris netting is not permitted, as this increases wind load.

Free-standing towers are highly useful where tie-ins are impossible, but they demand strict adherence to TG20:21 guidance to guarantee safety.

Mobile Towers

Mobile towers are a variation of free-standing towers fitted with swivel-type castors, providing flexibility to reposition the scaffold easily on site. They are commonly used for lightweight construction, maintenance, and fit-out tasks, where mobility is essential.

According to TG20:21, mobile towers must comply with strict rules:

• Height-to-base ratios: 3.5:1 indoors and 3:1 outdoors.
• Load classes: 0.75kN/m² to 2.0kN/m² depending on bay size and design.
• Maximum heights: up to 9.5m internally under Load Class 1, and 5.4m externally under Load Class 3.
• Bracing: all four sides must be braced, with plan bracing at alternate lifts, including the foot lift and top lift.
• Couplers: right-angle couplers must secure ledgers and transoms.
• Castors: must include effective brakes engaged whenever in use, and towers must never be moved while occupied.

When erected correctly, mobile towers provide a safe, adaptable working platform that balances convenience with TG20:21 compliance.

Birdcages

Birdcage scaffolds are grid-pattern structures widely used for internal fit-out projects, ceiling works, and mechanical/electrical installations where safe access is required across large flat areas.

Under TG20:21, birdcages fall into three standard load classes:

• Class 1 (0.75kN/m²) – maximum bay size 2.1m × 2.1m
• Class 2 (1.5kN/m²) – maximum bay size 1.9m × 1.9m
• Class 3 (2.0kN/m²) – maximum bay size 1.7m × 1.7m

Key requirements include:

• Lift heights: maximum 2.0m, with the first lift permitted up to 2.5m.
• Couplers: ledgers fixed to standards with right-angle couplers; principal transoms also fixed with right-angle couplers, with board-bearing transoms allowed on putlog couplers.
• Boarding options: top lift only, top plus perimeter lifts, or fully boarded platforms.
• Foot lifts: mandatory for all single-lift birdcages.
• Bracing: continuous bracing in both directions, with tie patterns specified in TG20 compliance sheets.

Birdcages may be tied, butted, or free-standing, depending on site conditions and exposure. When free-standing, strict height-to-base ratios and robust bracing are essential to maintain stability.

Chimney Stack Scaffolding

A chimney scaffold is a specialist temporary access structure built to provide a protected working platform around ridge, eaves or gable chimneys on pitched roofs.

Under TG20:21, chimney stack scaffolds are limited to Class 2 (1.5kN/m²) loading, making them suitable for light maintenance, inspection, and repair tasks.

Key requirements include:

• Support from independent scaffolding or towers at ground level, with diagonal struts used to transfer loads away from the roof.
• Bearing boards spanning at least two rafters wherever standards rest directly on the roof.
• Plan bracing under walkways that exceed one bay in length to maintain stability.
• Secure ties at the eaves, verge, or ridge as set out in TG20:21 compliance sheets.

Chimney scaffolds are compact but highly technical, requiring careful installation and regular inspection to ensure safety when working at height on roof structures.

Putlog (Tied) Scaffolding

Putlog scaffolding is a type of façade scaffolding constructed with a single row of standards positioned parallel to the building.

The scaffold is supported by inserting putlogs into the brickwork, typically between courses, using putlog blades or adaptors designed to bear into the masonry.

Under TG20:21, putlog scaffolding is only suitable for relatively low-height masonry projects, with TG20 compliance sheets generally limited to a maximum height of 6.0m.

Unlike independent scaffolding, putlog scaffolds are not ledger-braced above the first lift, which restricts their use on taller or more complex façades.

TG20 guidance recommends independent scaffolding for most façade access, but putlog scaffolding may still be appropriate for smaller brickwork projects, provided all construction, bracing, tie, and foundation requirements are met.

Where additional height, loading, sheeting, or stability is required, TG20 advises either switching to independent scaffolding or obtaining a bespoke scaffold design from a competent designer.

Why Use TG20:21-Compliant Scaffolding?

With ever-stricter construction safety standards, TG20:21-compliant scaffolding is essential for safe, efficient site operations. Following TG20:21 ensures scaffolds are built to tested designs, with correct load classes, bay sizes, bracing patterns, and tie requirements.

For clients, this means fewer delays, smoother inspections, and confidence that the scaffold solution meets both HSE expectations and principal contractor requirements.

This reduces risk, improves efficiency, and helps contractors meet HSE expectations.

Key Benefits of TG20:21 Compliance

Other Scaffolding Types Not Covered in TG20:21

While TG20:21 focuses on common tube-and-fitting scaffold configurations, other specialised systems are widely used across UK construction. These include system scaffolding with pre-engineered components, stair towers for safe vertical access, and suspended scaffolds operating from rooftop rigging.

Contractors may also deploy gantries for pedestrian protection or bespoke modular solutions when TG20-compliant arrangements are unsuitable. In such cases, a temporary works design by a qualified engineer is essential.

System Scaffolding and Modular Alternatives

Although tube-and-fitting scaffolding remains the UK standard, system scaffolding offers efficiency through its pre-engineered components and quick connections.

Two of the most popular systems are:

• Cuplock Scaffolding – designed for heavy-duty use, with locking cups at 50cm intervals that allow rapid and secure assembly.
• Layher Scaffolding – a modular system using rosette connections, offering high adaptability and reduced assembly times, especially on complex structures.

Benefits of modular systems include:

• Faster assembly and dismantling compared to tube-and-fitting.
• Consistent component quality and reduced reliance on skilled labour.
• Enhanced safety features built into system design.

Stair Towers, Gantries, Temporary Roofs and Hanging Scaffolds

Some site conditions require specialist scaffolding outside TG20:21 parameters:

• Stair Towers – provide safer, more efficient vertical access for workers, tools, and materials than ladders.
• Gantry Scaffolds – elevated frameworks used for overhead works or pedestrian protection, often spanning entrances or walkways.
• Hanging Scaffolds – platforms suspended from numerous different places, including roof-level anchors, gantries, or cranes, used where scaffolding can’t be erected from the ground. They are especially valuable for high-rise construction, bridges, or partial structures under construction.
• Temporary roof scaffolding – provides weather protection over exposed buildings and construction works. Often formed using lightweight aluminium beams and suitable coverings, temporary roofs are commonly used for long-term refurbishments, heritage projects and weather-sensitive work.

Hanging scaffolds place the entire load on the supporting structure, so engineering checks and proper permits are essential to guarantee safety and compliance.

When a Bespoke Scaffold Design Is Needed

While TG20:21 compliance sheets cover a wide range of standard scaffolding setups, there are many situations where a bespoke scaffold design is required.

A custom design becomes necessary when:

• The scaffold falls outside TG20:21 parameters (e.g. unusual bay sizes, excessive lift heights, or atypical bracing).
• Additional loading is needed beyond standard limits, such as heavy plant or material storage.
• The scaffold must work around complex architectural features, projections, or irregular building shapes.
• Environmental factors like wind exposure, sheeting/netting, or restricted tie opportunities create added risks.
• The client or principal contractor specifically requests a design, which is common on large projects for health, safety, and coordination reasons.

Bespoke scaffold designs are produced by temporary works engineers and typically include detailed calculations, drawings, and tie schedules.

They can also integrate multiple scaffold systems, for example, combining independent scaffolds with loading bays, birdcages, or stair towers, to provide a safe, practical, and compliant access solution.

Why Choose Band of Brothers for Scaffolding Services?

When it comes to scaffolding, Band of Brothers Scaffolding combines TG20:21 compliance, CISRS-accredited teams, and decades of hands-on experience to deliver safe and reliable access solutions.

• Tailored Site Surveys – Every project begins with a full assessment to ensure the scaffold configuration matches your site’s unique requirements.
• Quality Materials & Inspections – All equipment is sourced from trusted manufacturers and undergoes regular safety checks.
• Proven Experience – From heavy-load requirements to complex access challenges, the team delivers residential scaffolding, commercial scaffolding and industrial scaffolding across a wide range of projects.
• Safety & Reliability – A safety-first approach and a consistent track record make them a trusted partner across Surrey and the South East.

Whether you need independent scaffolding, birdcages, loading bays, or chimney stack solutions, Band of Brothers provides professional scaffolding services built on precision, safety, and reliability.

Conclusion

Choosing TG20:21-compliant scaffolding guarantees safe, efficient, and regulation-ready access solutions for any construction project. From independent scaffolds and loading bays to birdcages and chimney stacks, selecting the right system ensures both safety and productivity on site.

With our CISRS-accredited team and commitment to best practice, Band of Brothers Scaffolding delivers tailored solutions that meet TG20:21 standards or bespoke designs where required. Trust our expertise to keep your next project safe, compliant, and on schedule.

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