01
Define what was evaluated
A statement about a stone sample is different from a test of an installed roof assembly. Ask what was tested, which method was used and what the result means. Obtain the complete report or approval documentation when a performance claim is central to the design; a logo in a brochure is not enough information for a specification.
02
Match the proposed assembly
Identify the slate dimensions and thickness, fastening, supporting deck, underlayment and installation arrangement described in the evidence. Ask the designer to assess differences between those details and the proposed job. Do not transfer a result from one proprietary assembly to another simply because both use natural slate.
03
Check the scope of an approval
Where a project requires an approval or listing, have the project team check its current status, scope and conditions with the relevant authority. Keep that confirmation with the approved submittal. The useful question is whether the documented system is suitable for this building and location.
04
Separate testing from a promise of no damage
A rating is not a prediction that a roof will escape every storm. Age, condition, impact characteristics, edge details and installation can affect the outcome. Compare maintenance requirements and repair methods alongside the claimed performance, and document the roof before severe weather for a meaningful condition record.