Technical Booklet G Resistance to the Passage of Sound·Page 49·2.91
External cavity wall closure at eaves level
External cavity walls should be closed at eaves level with a cavity stop such as mineral wool, and rigid connections between inner and external wall leaves should be avoided or only bonded to one leaf.
Where there is an external cavity wall, the cavity should be closed at eaves level with a cavity stop e.g. mineral wool (see Diagram 2.26). A rigid connection between the inner and external wall leaves should be avoided. If a rigid material is used, then it should only be rigidly bonded to one leaf.
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