Describe the roof and the tear-off
Include the approximate roof area and how many layers you expect to remove. Flag decking, flashing, or other material that may end up in the load and ask what can be mixed.
Account for the weight of shingles
The bin can look as though it has plenty of space while the shingles already make for a heavy load. Ask about weight limits and loading guidance before tear-off day.
Leave space for crews, suppliers, and pickup
Review where roofing material will be delivered and where vehicles and ladders will go. Choose a proposed bin spot that the truck can reach both at the start of the job and after the roof is complete.