What is the minimum tread depth for stairs under BP 220?

The minimum tread depth for stairs under BP 220 is established at 250 mm. This requirement is critical as it ensures that stairs are safe and usable. Adequate tread depth provides sufficient space for users to place their feet securely, which is essential for safety, particularly in preventing slips and falls.

In the context of stair design, 250 mm serves as a guideline to promote accessibility and comfort, facilitating ease of movement for individuals using the stairs, including those with mobility challenges. Adhering to this standard helps in supporting building codes that prioritize public safety and accessibility.

Stating that the correct answer is 200 mm would imply that the tread depth is insufficient for safe use, which goes against the standards outlined in BP 220. Hence, understanding the dimensions required is vital for compliance with building codes and ensuring safe architectural designs.