Of the two most common subfloor materials builders often debate which is best.
Best attic subfloor.
The best you can hope for is perhaps to lay some thin plywood platforms down over the bottom truss members and use them to store lightweight items.
Plywood or chipboard is the least expensive option for storage flooring.
Plywood is familiar to most people it is a sheet material made from layers of wood oriented in opposite directions from layer to layer.
Since the boards are sold in 4 foot by 8 foot sheets you may need to cut them into 2 foot wide strips to get them into the attic space.
Osb oriented strand board is a different form of sheet material.
The decision regarding the thickness of plywood to use for the subfloor in the attic has a lot to do with how you intend to use the attic and it also depends on the spacing of the ceiling joists.
Apa rated subfloor panel osb is a material with high mechanical properties that make it particularly suitable for load bearing applications in construction.
The wood should be at least 5 8 inch thick to handle a heavy load.