Is loft board permeable

[benaround3]

I intend to board my loft floor on 7” loft legs after adding glass fibre insulation over the joists.

There are no condensation issues at present and I will continue to monitor this.

The ceiling below is plasterboard from the 1950s and there is no vapour barrier.

My question is, as I cannot verify whether standard loft board is vapour permeable, would I reduce risk of condensation under the boards if I drilled vent holes in them?

 

[foxhole]

If there is insulation under boards then there is no where for damp warm air to cause condensation, not that there should be any your loft .

 

[benaround3]

But what about vapour rising through the ceiling board, which I believe is permeable? The underside of the board is on the cold side of the insulation, after all