Keeping an insulated attic takes constant maintenance and consistent time investment. Attic insulation takes some work on the homeowner's part, so it's imperative to become familiar with the tools and terminology that come with attic insulation.
First things first, make sure the height of your insulation is as high as it should be. While some insulation settles over time (rock wool insulation), it will take manual application to raise your insulation levels.
You can use cellulose insulation to raise this height. Simply pouring it onto the floor and spreading it amongst the attic will level it out for better insulation.
Bat insulation is another facet of the insulation process. This will ensure that there's no vapor barrier between the over and under insulation so that no moisture is trapped. It must be ran perpendicular to the joists of the attic for a tight seal. Be sure to make your measurements in inches. A knife will be needed to cut the pieces of bat insulation into clean, arrangeable pieces.
Lastly, cover up the subfloor with bat insulation pieces that you have available to you. After creating a wooden platform with strand board, you may safely store items in your attic on top..