Which document is used to request materials from the contractor's storage bins?

The document used to request materials from the contractor's storage bins is a stock requisition. This type of document serves as an official request to withdraw materials from inventory for use in projects. It ensures that there is proper tracking and management of materials, which is essential for maintaining accurate inventory levels and for accountability in construction projects.

When a contractor needs specific materials from storage, they fill out a stock requisition to formally document the request. This process helps in preventing misunderstandings and ensures that the right materials are used in the right quantities. The stock requisition typically includes details such as the type of material required, the quantity, and the project for which it is intended.

The other options are related to different aspects of material handling and procurement. A material invoice is a document that records the sale of materials and the amounts owed, while a purchase order is used to formally order materials from suppliers rather than requesting them from existing inventory. Shipment confirmation serves to verify that materials have been delivered but does not pertain to internal requests for materials from storage. Each of these documents plays a different role in the supply chain and inventory management, but the stock requisition is specifically the one used for requesting items from stored supplies.