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Scaffold guardrail, midrail and toe board heights compared
Quick answer: OSHA 38–45 in (0.97–1.2 m). BS EN 12811-1 at least 1.0 m, never below 950 mm (the UK legal minimum). Saudi Aramco CSM 0.95–1.15 m. The midrail, toe board and fall-height rules differ more than the top rail does.
Side by side
Each value with the document it comes from.
| Requirement | OSHA 1926 Subpart L USA | BS EN 12811-1 · TG20 UK and Europe | Saudi Aramco CSM · GI 8.001 Saudi Aramco sites |
|---|---|---|---|
| Top guardrail height | 38–45 in (0.97–1.2 m)Supported scaffolds made or placed in service after 1 Jan 2000. May be higher when conditions warrant, if every other guardrail rule is met.29 CFR 1926.451(g)(4)(ii) | At least 1.0 m (never below 950 mm)Top surface of the principal guardrail above the working level, along its whole length. UK law: at least 950 mm.BS EN 12811-1:2003 5.5.2; Work at Height Regulations 2005 Sch. 2 | 0.95–1.15 m (38–45 in)Top edge of the toprail above the platform.CSM II-2 §2.5.4 B |
| Midrail or intermediate protection | About midwayMidrail roughly halfway between the top edge and the platform. Crossbracing can count as the midrail only where the braces cross 20–30 in above the platform.29 CFR 1926.451(g)(4)(iv), (g)(4)(xv) | No gap over 470 mmIntermediate protection so that no unprotected gap is more than 470 mm.Work at Height Regulations 2005 Sch. 2 para 3 | About halfway, inside the uprightsMidrail about halfway up; toprails and midrails fixed to the inside of the uprights, which stand no more than 2.5 m apart unless the system maker allows more.CSM II-2 §2.5.4, §2.5.4 D |
| Toe board | At least 3-1/2 in (9 cm)Measured from its top edge to the walking surface, with no more than 1/4 in clearance underneath.29 CFR 1926.451(h)(4)(ii) | At least 150 mmTop of the toe board above the next working level. Overlaying the deck reduces it: check again.BS EN 12811-1:2003 5.5.4 | At least 100 mmNo more than 6 mm above the platform; wood at least 25 mm thick, clamped along the outer edge.CSM II-2 §2.5.5 B |
| When edge protection is needed | More than 10 ft (3.1 m)Each worker more than 10 ft above a lower level needs guardrails or personal fall arrest.29 CFR 1926.451(g)(1) | Any height that could injureThere is no minimum height in UK law: the rules apply wherever a person could fall a distance liable to cause injury.Work at Height Regulations 2005 reg. 2 | 1.8 m (6 ft) or moreGuardrails on all open sides and ends where people could fall 1.8 m or more.CSM II-2 §2.5.4 A |
| Gap between platform and work face | 14 in or lessUnless a guardrail or fall arrest is used on that edge. 18 in for plastering and lathing; 3 in for outrigger scaffolds.29 CFR 1926.451(b)(3) | —Not set as one figure in these documents; follow the design or the TG20 sheet. | Under 360 mm: no guardrail on that edgeBut falling objects must still be stopped: planks over the gap, toe boards, nets or barricades.CSM II-2 §2.5.6 A |
| Toprail strength | 200 lb (890 N)On supported scaffolds, applied downward or outward at any point on the top edge.29 CFR 1926.451(g)(4)(vii) | —Set by the side-protection loads in the standard; not repeated here. | 90 kg (200 lb)In any downward or horizontal direction at any point on the toprail, system scaffolds included.CSM II-2 §2.5.4 E |
Summary for learning, checked on 24 October 2026. Values as written in the documents named, as used in the AL-YASSIN question banks. TG20 values are from TG20:13; check TG20:21. Verify against the latest edition and your project's own rules before you use any figure. AL-YASSIN is independent and is not endorsed by OSHA, BSI, NASC or Saudi Aramco. — means the document does not give it as one figure here.
Mistakes we see in our exams
- Measuring from the wrong level. Height counts from the surface people stand on, not from the bearer or the main deck below a raised platform.
- Overlaying the deck with extra boards and forgetting that the toe board and guardrail are now lower.
- Treating sheeting or netting as side protection. BS EN 12811-1 says cladding alone does not count.
- Setting the toe board too far out: under BS EN 12811-1 its outer face must be within 80 mm of the guardrail line.
- Using the old OSHA 36–45 in range on frames that were not both made and put in service before 1 January 2000.
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Questions
What is the OSHA guardrail height for scaffolds?
Between 38 and 45 inches (0.97–1.2 m) above the platform for supported scaffolds made or placed in service after 1 January 2000, under 29 CFR 1926.451(g)(4)(ii). It may be higher when conditions warrant if all other guardrail rules are met. Verify against the current eCFR.
What is the minimum guardrail height in the UK?
The Work at Height Regulations 2005 set at least 950 mm. BS EN 12811-1 asks for the top of the principal guardrail to be at least 1.0 m above the working level, with 950 mm as the absolute minimum. Verify against the latest edition.
What is the Saudi Aramco scaffold toprail height?
Not less than 0.95 m and not more than 1.15 m above the platform, under CSM II-2 §2.5.4 B. Verify against the latest edition.
How high must a scaffold toe board be?
OSHA: at least 3-1/2 in (9 cm). BS EN 12811-1: at least 150 mm. Saudi Aramco CSM: at least 100 mm, no more than 6 mm above the platform. Verify against the latest editions.