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[email protected] nicksanspam@ece.villanova.edu is offline
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Default Gravel floor in garage

wrote:

... The cold gravel floor causes condensation when warm damp air contacts
it, the moisture drops through the stone to the vapour barier, and cannot
get away. Earth warms up a bit - becomes warmer than the air above,
moisture leaves and condenses on the cold car above.


This could also happen with concrete, which absorbs about 1% moisture
by weight as the room RH rises from 40 to 60% and gives it back
as the room RH falls.

Nick