What is TG20:21?
TG20:21 is the scaffolding industry's guidance for building standard tube and fitting scaffolds safely without a bespoke design. If your scaffold fits inside its limits you should get a TG20:21 compliance sheet; if it does not, it needs a design with drawings and calculations.
What TG20:21 is
TG20 is technical guidance published for the UK scaffolding industry. The current edition is TG20:21. It sets out tested configurations for common tube and fitting scaffolds: how far apart the standards can be, how many ties are needed, what loads the boards can carry, and how sheeting or netting changes all of that.
It sits under the European standard BS EN 12811, which covers the design of temporary works equipment. TG20:21 turns that standard into configurations a qualified scaffolder can build to without an engineer doing the maths every time.
What a compliance sheet is
A compliance sheet is the paperwork that shows your particular scaffold falls inside the TG20:21 limits. It records the height, the bay lengths, the loading class, the tie pattern and whether it is sheeted. It is produced from the TG20:21 software or tables.
It is the evidence that someone checked the scaffold against the guidance, rather than building it by eye.
Why you should ask to see one
If you are a homeowner, the compliance sheet tells you the scaffold on your house was worked out, not guessed. If something goes wrong, it is part of the record showing the structure was right for the job.
If you are a main contractor, you are responsible for the site. Asking for the compliance sheet, or the design, before anyone climbs the scaffold is basic due diligence. Your principal designer and your insurer will expect it.
When a scaffold falls outside TG20:21
TG20:21 covers a lot, but not everything. A scaffold needs a bespoke design when, for example:
- It is taller than the guidance allows for that configuration.
- It carries heavy loads, such as stacked blocks, slates or a loading bay.
- It is fully sheeted or wrapped in an exposed position, where the wind load goes up sharply.
- It is a temporary roof, a birdcage, a cantilever, a bridge or a structure over a live road or pavement.
- The building cannot take normal ties, such as a listed facade or a building with poor masonry.
Compliance sheet or design: who produces it
The Work at Height Regulations require strength and stability calculations for every scaffold, unless it is built to a generally recognised standard configuration. For tube and fitting work that means a TG20:21 compliance sheet. So there are only two lawful routes: a compliance sheet, or a bespoke design with calculations by a competent person.
We produce the TG20:21 compliance sheet ourselves, using the TG20 eGuide, rather than waiting on a third party. That covers independent tied scaffolds, putlog scaffolds, birdcages, towers, loading bays and chimney stack scaffolds, with the wind exposure worked out for your postcode. Most domestic and light commercial work sits inside it.
Anything outside TG20:21 goes to an independent scaffold designer, and we confirm their professional indemnity cover before they start. Temporary roofs, sheeted scaffolds beyond the wind limits, cantilevers, truss-outs, facade retention, spans over fragile roofs and any tie pattern that departs from the guidance all fall into that group.
Either way, your job file holds one document or the other, and it comes to you with the handover paperwork.
Common questions
- Is TG20:21 a legal requirement?
- TG20:21 is industry guidance, not a law. But the law requires scaffolds to be designed or built to a recognised standard configuration, and TG20:21 is how the industry shows that for tube and fitting work.
- Does every scaffold need a compliance sheet?
- Every scaffold built to TG20:21 should have one. A scaffold that falls outside the guidance needs a design instead.
- Who produces the compliance sheet?
- The scaffolding contractor, using the TG20:21 software or tables. It should come to you with the handover.
- What is the difference between TG20:21 and BS EN 12811?
- BS EN 12811 is the European standard for designing scaffolds. TG20:21 is the UK guidance that applies it to standard tube and fitting configurations, so common scaffolds do not each need an engineer.
- How do I know if my job needs a design?
- Your scaffolder should tell you at the assessment stage. Height, loading, sheeting, temporary roofs and anything spanning a road are the usual triggers.
Want to know whether your scaffold needs a design?
Tell us about the job and the written assessment will say whether it falls inside TG20:21 or needs drawings and calculations.