01
Length follows the assembly
The nail must pass through the slate and achieve suitable embedment in the specified deck without creating unnecessary penetration below exposed interiors. Thicker slate and battens change the requirement.
02
The head supports without clamping
A broad roofing-nail head supports the slate at the hole. Drive until secure but not tight; the piece should hang naturally rather than being pinned against an uneven surface.
03
Copper quality matters
Use solid copper roofing nails of the specified shank and head, not merely copper-colored or thinly plated fasteners. Store them dry and verify the package against the project requirement.