Which of these is NOT appropriate for protecting expansion joints in a low-slope roofing system?

In the context of low-slope roofing systems, expansion joints are critical components that allow for movement and expansion due to temperature fluctuations, settling, and other factors. It is essential to protect these joints to prevent water intrusion and maintain the integrity of the roofing system.

Using wooden plates for the protection of expansion joints is not appropriate because wood can absorb moisture, leading to deterioration, warping, or decay over time. This undermines the effectiveness of the expansion joint by introducing potential vulnerabilities in the waterproofing capabilities of the roofing assembly. Additionally, wood does not provide the flexibility needed to accommodate the movement that expansion joints are designed for; as a result, it may become a source of additional problems rather than a solution.

On the other hand, rigid covers, flexible sealants, and metal flashing are all suitable materials for protecting expansion joints. Rigid covers can provide a solid barrier against environmental elements while allowing for some degree of movement. Flexible sealants are specifically designed to accommodate movement and can effectively seal gaps, preventing water from penetrating the joint. Metal flashing offers durability and resistance to various weather conditions, making it a strong choice for protecting vulnerable areas like expansion joints.

In summary, wooden plates are not suitable for this application due to their susceptibility to moisture and lack