Technical Booklet G Resistance to the Passage of Sound·Page 58·2.131
Wall types 3.1 and 3.2 – roof space treatment with ceiling
Where the roof or loft space is not habitable and a ceiling with minimum mass of 10 kg/m² and sealed joints is provided, independent panels may be omitted in the roof space if the separating wall above the ceiling has minimum mass of 150 kg/m².
Where the roof or loft space is not a habitable room and there is a ceiling with a minimum mass per unit area of 10 kg/m2 and with sealed joints, the independent panels may be omitted in the roof space and the mass per unit area of the separating wall above the ceiling may be a minimum of 150 kg/m2 (see Diagram 2.35).
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