[header] How to insulate a drop ceiling [title] Ensure that your ceiling tiles can support the weight of the insulation. [step] Although batt insulation is fairly lightweight, it can put an undue amount of stress on flimsy drop ceiling tiles and break them. [substeps] If you have fiberglass tiles, you'll need to replace them before proceeding. 
Fiberglass ceiling tiles cannot support the weight of insulation. If you have the more common wood-and-gypsum ceiling tiles, they will need to be at least 5/8 inch (15 mm) thick to be used safely with batt insulation.