I am a fairly new homeowner. I own a "raised ranch" style home in suburban Chicago (main floor above grade, mostly furnished basement below). The stairs to the basement are roughly in the center of the home. The stairwell is drywalled on sides and overhead. Together with adjoining interior walls it forms a void in the interior of the main story that is open to the attic on top. Some attic insulation may have previously spanned the "top" of it, but at the present it's just a wedge-shaped well/void in the joist surface of the attic.
I think this void is the cause of major thermal loss in the adjoining hall closet and bedroom. I would like to insulate the void, but keep the project scope small and cost efficient - mostly interested to see what difference it would make this winter. Current idea is to dump blow-in insulation into it, as that can be done in an hour or so. Wondering if that's acceptable or DIY gone wrong. Only negative I can think of is difficulty in scooping that up in case the need to undo.