Final answer:
The last part to fail in a slate roof system can vary, but in general, the slate tiles are the most durable. However, the flashings are more susceptible to deterioration and can compromise the integrity of the system if they fail.
Step-by-step explanation:
A slate roof system consists of several components, including the slate tiles, underlayment, flashings, and fasteners. The last part to fail in a slate roof system can vary depending on numerous factors, such as the quality of installation, maintenance, and exposure to environmental conditions.
However, in general, the slate tiles themselves tend to be the most durable and long-lasting part of the system. They are typically made of a natural stone material, which is highly resistant to weathering and can withstand the test of time.
On the other hand, the flashings, which are typically made of metal or synthetic materials, can be susceptible to deterioration over time. Flashings play a crucial role in preventing water from entering the roof system at vulnerable areas, such as roof valleys and chimneys. If the flashings fail, it can lead to water leaks and eventually compromise the integrity of the entire roof system.