Which condition makes timber scaffold planks unfit for use?

Timber scaffold planks that are twisted, broken, or split are unfit for use due to structural integrity concerns. The primary role of scaffold planks is to provide a safe and stable working platform; any alterations to their original shape or structure can compromise this purpose. Twisting can result in uneven surfaces that may not support weight appropriately, breaking indicates that the wood has lost its ability to bear loads, and splitting can create dangerous gaps or fractures that could lead to accidents. Consequently, all these conditions significantly increase the risk of failure while in use.

In contrast, scaffold planks that may have a fresh coat of paint are generally safe as long as the paint does not conceal any damage. Planks made of composite materials can also be suitable for scaffolding, provided they meet the necessary safety and structural standards. Finally, while planks that are too short for the application can create issues related to coverage and safety, they do not reflect inherent damage to the material itself, which makes twisted, broken, or split planks a primary concern for safety regulations.