01
Material choices change the installed system
Slate origin, color, thickness, size, finish, sorting and testing affect price. Larger or thicker pieces may change weight, handling and labor. Blends and specialty shapes add layout work. Compare quotations using the same product specification rather than a generic line labeled simply ‘slate.’
02
Roof geometry drives labor
A simple gable is different from a steep roof with valleys, dormers, turrets, walls and many penetrations. Tear-off, staging, protection, access, roof height and site conditions can substantially affect labor. Copper valleys, step flashing and custom sheet-metal work also deserve separate attention.
03
Repair and replacement are different decisions
An older slate roof may need targeted repairs and renewed flashings rather than wholesale replacement. A qualified inspection should separate sound slate from failed details. The lowest initial proposal is not necessarily the lowest lifetime cost if it removes reusable material or substitutes short-lived details.