Drying time for flat roof deck

[ryder72]

Long story but our flat roof deck (build up is joists, air-tight membrane, 22mm OSB3 deck, 150mm PIR insulation, 150-50mm tapered PIR insulation) was wet from a downpour before it was covered up with the single ply membrane. Water got through the gaps in the insulation etc and was trapped between the OSB and membrane. We had to slash open the membrane to let the water drain out and the deck has been left to air for around 4 weeks now. The OSB feels pretty dry to touch and no new water has fallen on the deck or no new moisture is coming through the OSB.

 

windows have been left open to ventilate the house and fans set up to accelerate the drying. There is no way to be 100% sure that there is no residual moisture trapped between the boards apart from lifting up the insulation and this will almost certainly damage the boards.

 

Does anyone have any opinion on the best way forward to determine when the roof has reached an acceptable level of dryness before being covered up. My concern is that once the roof membrane is on and air/moisture membrane taped up on the underside, any moisture trapped in the board is permanently trapped. What implications could this have?

 

Any inputs gratefully received.