"xavier" wrote in message
om...
whereas putting it underneath would still allow condensation on the
?joists and underside of the boards - and then keep it there !

Visible condensation won't normally occur in the subfloor space if
it's ventilated adequately and the inclusion of a dpm separating it
from the living spaces will reduce the risk even further (as indeed
would another dpm over the actual ground itself). The Interstitial
Condensation ocurring because of previously mentioned circumstances is
the greater risk.

My suggestion was that since the Rockwool is pressing the DPM against the
underside of the joists and floorboards, these won't be getting any
ventilation and in fact are at quite some risk of damage. But this depends
on whether moist air would condense on top of the DPM above the Rockwool or
not ? Any thoughts ?