Junctions with floor penetrations (excluding gas pipes)

Pipes and ducts that penetrate a floor separating habitable rooms in different flats and maisonettes should be enclosed for the full height in each flat and maisonette (see Diagram 3.17). The enclosure should be constructed of material having a mass per unit area of at least 15 kg/m2. Either line the enclosure, or wrap the duct or pipe within the enclosure, with 25 mm unfaced mineral wool. Leave a small gap (approximately 5 mm) between the enclosure and floating layer and seal with sealant or neoprene. Where floating floor (a) or (b) is used the enclosure may go down to the floor base, but ensure that the enclosure is isolated from the floating layer. Penetrations through a separating floor by ducts and pipes should have fire protection.