01
Label the stock by roof area
Keep the product description, dimensions, thickness selection, supplier, and purchase date with the stored material. Where several blends or sizes were used, separate and label them. Include a roof sketch showing their locations. Do not assume a future repairer will recognize the correct slate from a pile containing unrelated leftovers.
02
Choose a documented storage location
Have the contractor recommend suitable stable storage and handling for the quantity retained. Record the location in the maintenance file and give the owner an inventory. Keep the stock accessible without placing heavy material on an unverified shelf or attic floor. Update the inventory when repairs consume pieces so the next project does not discover that an apparently full reserve contains only unsuitable scraps.