Hi, we are now getting to the stage with our loft conversion where the Celotex insulation boards need to be installed. The specs are 75mm Celotex boards between the joists overlaid with 40mm Celotex boards and then plaster boards over those.
My question is that the thickness of the roof joists is 95mm so with 75mm Celotex in between leaves a gap of 20mm from the insulation board to the back of the outside tiles (tiles are backed with the appropriate underlay sheeting).
I am assuming this 20mm gap is there for ventilation / condensation reasons, however I would like to make the roof as soundproof as possible due to local road noise and Sea Gull noise, as such is there a reason why this void can't be filled with Rock Wool style insulation as an additional acoustic barrier?
All responses welcome, and thanks for reading this!
My question is that the thickness of the roof joists is 95mm so with 75mm Celotex in between leaves a gap of 20mm from the insulation board to the back of the outside tiles (tiles are backed with the appropriate underlay sheeting).
I am assuming this 20mm gap is there for ventilation / condensation reasons, however I would like to make the roof as soundproof as possible due to local road noise and Sea Gull noise, as such is there a reason why this void can't be filled with Rock Wool style insulation as an additional acoustic barrier?
All responses welcome, and thanks for reading this!
