On Oct 16, 12:21 am, wrote:
Looking to board my attic for storage; it has some scrappy Rockwool
and joists are 4"x2". I was wondering whether to plant 2"x2" timbers
on joists to allow for greater depth of Rockwool, or maybe the
chipboard would provide enough extra insulation? Another thought -
better grade insulation material in place of Rockwool but in the same
4" space? Any ideas welcomed.

Make sure you don't end up with condensation forming in the loft due
to the reduced temperature. The previous occupants in my house had
extra insulation with no vapour barrier and no ventilation.

MBQ