About 2 months ago I boarded a 12ft square area of my loft with OSB board. I checked on it today and noticed some of the boards have distorted, I lifted one of the boards and found it was wet and mouldy underneath.
The boards were fixed directly onto the ceiling joists, in between the joists is two layers of sheeps wool insulation. The top surface of the insulation is wet but below that is bone dry.
Below the insulation is wood wool ceilings boards, and beneath that is lime plaster, both of which are also bone dry.
I'm guessing humidity from the room below has passed though all the breathable layers (which are dry) and then condensed on the underside of the OSB boards.
I need to be able to protect the wool insulation from all the crap that comes off the underside of the tiles (I have no felting) but obviously I need to allow it to vent off all the moisture coming though. There is good ventilation from under the eaves, and generally the loft area is well ventilated. I read that I should have left at least 50mm gap between the underside of the boards and top of the insulation?
I'm thinking now that the best option would be to use those loft legs from B&Q to create a raised platform at least 50mm above the insulation and hope there is enough airflow underneath to ventilate it.
The boards were fixed directly onto the ceiling joists, in between the joists is two layers of sheeps wool insulation. The top surface of the insulation is wet but below that is bone dry.
Below the insulation is wood wool ceilings boards, and beneath that is lime plaster, both of which are also bone dry.
I'm guessing humidity from the room below has passed though all the breathable layers (which are dry) and then condensed on the underside of the OSB boards.
I need to be able to protect the wool insulation from all the crap that comes off the underside of the tiles (I have no felting) but obviously I need to allow it to vent off all the moisture coming though. There is good ventilation from under the eaves, and generally the loft area is well ventilated. I read that I should have left at least 50mm gap between the underside of the boards and top of the insulation?
I'm thinking now that the best option would be to use those loft legs from B&Q to create a raised platform at least 50mm above the insulation and hope there is enough airflow underneath to ventilate it.
