When a company incurs rent for its manufacturing operations, the rent is a product cost. It is common for the rent to be included in the manufacturing overhead that will be allocated or assigned to the products. That rent as part of the manufacturing overhead cost will cling to the products. If the products remain in inventory, the rent is included in the manufacturing overhead portion of the product's cost. When products are sold, the rent allocated to those products will be expensed as part of the cost of goods sold.
If the rent is for items involved in the selling function (rent for office space, equipment, autos, etc.) or if the rent is for items in the administrative function of the company, the rent is a period cost and will be expensed in the period when the expense is incurred. These rents will not be allocated to the products for external financial statements.