How high can thresholds at doorways be, if provided?

Thresholds at doorways play an important role in accessibility and safety. The maximum height for thresholds is often regulated by building codes and accessibility standards, such as the Americans with Disabilities Act (ADA). According to the ADA, thresholds should not exceed a height of 1/2 inch to ensure that doorways remain accessible, particularly for individuals using wheelchairs or mobility devices.

A threshold higher than this could create a barrier for users, making it difficult to pass through the doorway comfortably and safely. By maintaining the threshold height at or below 1/2 inch, it ensures easier transitions between spaces, enhancing the overall functionality of the space while complying with regulations designed to protect individuals with disabilities.

In summary, a threshold height of 1/2 inch maximum is supported by accessibility guidelines, making it the correct answer.