Do I need TG20 compliance or a bespoke scaffold design?

If you’re planning scaffolding on a UK project, the first question isn’t “tube or system?” — it’s:

Can this scaffold be built to a generally recognised standard configuration (TG20/TG30), or does it fall outside that scope and need a bespoke design?

TG20 (tube & fitting) and TG30 (system) exist to give the industry pre-engineered “standard solutions” — meaning many common scaffolds can be erected without a separate one-off design, as long as the build matches the compliance requirements exactly.

What TG20 compliance actually means

TG20:21 provides a structured route to a compliant scaffold for a defined range of configurations. It’s based on structural research and calculation, and is intended to cover common access arrangements when the scaffold geometry, loading and tie strategy sit within the “rules” of the guidance.

HSE specifically notes that TG20:21 provides compliant scaffolds for a limited range of items like cantilevers, loading bays, bridges and fans — and it also sets limitations on how many working platforms may be in use at once in certain cases.

So the key phrase is: “limited range.”

When TG20 is usually appropriate

TG20 is typically a good fit when you have:

• Standard independent tied access scaffolds to relatively regular façades

• Straightforward lift heights and consistent bay lengths

• “Normal” platform loading expectations (i.e., access/working, not heavy storage)

• A tie arrangement that can be achieved as required and installed progressively

• No unusual geometry, offsets, transfer conditions, or heavy ancillaries (more on that below)

If the scaffold can be erected to a TG20 compliance sheet (and it’s actually built that way), you get a fast, well-recognised compliance route.

When you should stop and commission a bespoke design

In practice, scaffolds often drift outside TG20 scope because the site conditions are messy, the façade is awkward, or the scaffold is being asked to do “more than access.”

You’re usually into bespoke design territory when any of the following apply:

1) The geometry is non-standard

• Curved façades, setbacks, big returns, irregular plan shapes

• Significant bridging/gantries over openings, roads, roofs, glazed areas, etc.

• Cantilevers/needles/transfer arrangements beyond the “limited range” TG20 covers

2) The loading is non-standard

• Heavy-duty loading bays, hoists, rubbish chutes, mast climbers interface

• Sheet/clad/scaffold wrap that materially increases wind loading

• Significant temporary works interface (façade retention, propping, restricted foundation capacity)

3) The ties are constrained or unreliable

• You can’t achieve the required tie positions due to façade restrictions

• The substrate is questionable and requires testing/alternative anchor strategy

• You need rakers, buttresses, plan bracing changes, or non-typical stability solutions
  (HSE emphasises scaffolds must be tied/braced/stabilised and ties must be used within their safe working load.)

4) There are unusual risk interfaces

• Public protection fans/gantries in tight city sites

• Rail/trackside constraints and third-party approvals

• Complex sequencing where stability changes phase-by-phase

Why bespoke design is often cheaper than “making TG20 fit”

This sounds counterintuitive, but here’s the reality:

Trying to force a scaffold into TG20 scope can lead to:

• Over-tied, over-tubed scaffolds (material + labour increases)

• Site delays when the “idealised” tie positions aren’t achievable

• Uncontrolled variations once erection starts (the real compliance killer)

A bespoke design can be more buildable because it’s engineered around what actually exists on site — including tie restrictions, ground limits, access constraints and sequencing.

Compliance note: designers’ duties and “risk by design”

Under CDM 2015, designers must eliminate foreseeable risks where possible and reduce/control those that remain, then provide information to others so they can manage residual risks.

In scaffold terms, that’s exactly what a proper design package should do: define the safe configuration, loading assumptions, stability system (ties/bracing/rakers), and any critical erection/dismantle notes.

A practical decision checklist

If you want a quick “go/no-go” test, ask:

1. Can we physically install ties where they’re required — and keep them in place?

2. Are we adding sheeting, signage, hoists, chutes, or anything wind-sensitive/heavy?

3. Are there bridges/cantilevers/gantries/temporary roofs or transfer conditions?

4. Is the façade/ground condition uncertain or restricted?

5. Would we be comfortable defending this scaffold configuration to an auditor/HSE if something went wrong?

If you answered “no” or “not sure” to any of the above, commission the design. It’s usually the quickest way to certainty.

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If you want, we can sanity-check your proposed arrangement quickly from an enquiry pack (photos, dimensions, intended use, and any constraints) and tell you whether TG20 compliance is viable or whether you’re into bespoke design territory.