01
Ask how the sample was chosen
A piece removed from one area may not represent another slope, a different material lot, or a later repair. Ask the assessor what other observations support the conclusion, including visible condition and the roof's history. Do not climb onto the roof or strike installed slates to perform your own test; access and handling can damage the roof and expose people to falls.
02
Connect the result to the decision
If a contractor recommends extensive work based on sample assessment, request an explanation of the sampling locations and limits. Material condition is only part of the roof system; flashings, fixings, and the supporting assembly still matter. Keep any test observations with the photographs and written assessment so future decisions can be traced to evidence rather than a remembered demonstration.