Joists are 8 to 10 inches deep so they only give you that much depth for insulation.
How to build above insulation storage in attic.
Attics are generally covered in batting or blown insulation.
Attic insulation between roof trusses.
But you need more and it s not as simple as crushing it or it won t insululate.
Screw the frame to the joists to secure it in place making sure not to screw into electrical wires.
Watch this easy diy guide on how to fit loft boards giving you a strong storage platform above even thick insulation in your loft or attic.
Full the spaces between the frame members with insulation.
Here are my suggestions.
By adding the boards you increase storage space for items not needed often allowing you to move those items out of the main house and reduce clutter.
If blown in insulation is used control the height or thickness of the layers so boards can by laid over top without having to compact the filler.
Rip 1 2 thick plywood to 24 widths so it will fit up the attic stairs.
Build a frame on 16 centers perpendicular to the attic floor joists.
Either build an elevated storage platform or strategically carve out an area of the attic toward the middle where less insulation is needed and reduce insulation in the interest of floor level storage there.
Even easier you can also use a prefabricated attic floor kit designed specifically to raise the attic floor above the insulation.