Additional Attic Insulation – Framing Question
I am planning on adding insulation to my currently uninsulated attic. This is an old Sears house built sometime in the forties. My current plan is to blow in either cellulose or fiberglass after sealing any penetrations or air leaks. In order to get the required R value for my climate I need to add an additional 8″ of space to fill with insulation. Since our attic is used for storage currently (has a tongue and groove floor installed sometime around the time the house was built) I would like to be able to use it for storage after.
My question is this:
Should I be concerned about additional loading of the 2×6 members (spaced 16″ o.c.) after adding 2×8 lumber with 1/2″ ply on top? Am I better off sistering up the joists with 2x12s instead of running them perpendicular? My only concern with sistering up the joists is getting the lumber up there in the lengths needed.
Could I sister the joists up with 2×8 and then do a perpendicular run of 2×6’s to nail the ply to?
I figured before I went and potentially caused structural issues to my house I should double check.