OHS Code Explanation Guide

Published Date: July 01, 2009
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Part 23 Scaffolds and Temporary Work Platforms

Section 329 Scaffold planks

Subsection 329(1)

Manufactured scaffold planks are often made of wood laminates or combinations of wood and metal. Because the planks may have properties that differ from those of conventional solid sawn lumber, manufactured planks must be used, stored, inspected and maintained according to the manufacturer’s specifications.

Subsections 329(2) and 329(3)

Solid sawn lumber scaffold planks must be graded as scaffold grade or better. Scaffold grade planks are assessed against numerous criteria that include density, knots, splits, warps, twists, decay and dimensions. These planks are also subjected to deflection tests and are capable of supporting loads expected during scaffold work. Planks that meet the inspection criteria are stamped as “scaffold grade” and bear a grade stamp.

Subsection 329(4)(a)

Before installing a scaffold plank on a scaffold, the plank must be visually inspected to ensure it is safe for use. Normal wear and tear and storage can damage a plank to the point that it is unsafe for continued use. Reasons for removing a plank from service include decay, conditions that reduce the thickness or width of the plank, damaged welds in the case of metal planks, and cracks in metal or composite planks.

Subsection 329(4)(b)

If visual inspection reveals damage that could affect the strength of the plank, the acceptability of the plank for continued use must be confirmed by load testing or the plank must be removed from service. Using the deflection test procedures and test criteria of ANSI Standard A10.8-1988, Construction and Demolition Operations – Scaffolding – Safety Requirements, the deflection of a scaffold plank under its design load must not exceed the span length divided by 60.

To test a plank, the plank is placed on stable supports set at the plank’s intended use span. The plank is then weighted with the intended load at the center of the span and the plank’s deflection measured.

If a plank is intended to support one worker over a 2.4 metre (8 feet) span, a 113 kilogram (250 pound) load must be placed at the plank’s centre and the resulting plank deflection measured. The deflection must not exceed 1/60th of 2.4 metres – a distance of 40 millimetres (1.6 inches). If the plank is to support two workers, the ANSI Standard recommends placing two 113 kilograms (250 pounds) weights on the plank, one 460 millimetres (18 inches) to the right of centre and one 460 millimetres (18 inches) to the left of centre. If the plank is to support three workers, ANSI recommends placing three 113 kilograms (250 pounds) weights on the plank, one at the centre, one 460 millimetres (18 inches) to the left of centre and one 460 millimetres (18 inches) to the right of centre.

Subsection 329(4)(c)

The minimum 150 millimetre (6 inch) distance reduces the likelihood of a plank slipping off its supporting ledger. Limiting the distance that a plank can extend beyond its supporting ledger to 300 millimetres (12 inches) discourages workers from using the extended area as part of their working platform. This reduces the chance of a worker causing the plank to flip up and out of position.

Subsection 329(4)(d)

Planks may be secured in many different ways. Some wooden planks use cleats, some steel or aluminum planks use hooks or recesses into which ledgers are positioned. The securement method must prevent movement of the plank in any direction that may create a danger to a worker.

Subsection 329(4)(5)

Scaffold planks are overlapped when scaffolds have multiple bays and a continuous work platform is required. The overlap in such cases must be at least 300 millimetres (12 inches) and occur only over supports as shown in Figure 23.6.

Figure 23.6 Plank overlap