Best Practice Measures for Cavity Masonry Separating Walls

Points to watch – Do (a) Do fill and seal all masonry joints with mortar. (b) Do keep the cavity leaves separate below ground floor level. (c) Do ensure that any external cavity wall is stopped with a cavity stop at the junction with the separating wall, unless the cavity is fully filled with mineral wool (seek manufacturer's advice for other suitable materials). (d) Do control flanking transmission from walls and floors connected to the separating wall as described in the guidance on junctions. (e) Do stagger the position of electrical sockets and switches on opposite sides of the separating wall. (f) Do ensure that flue blocks will not adversely affect the sound insulation and that a suitable finish is used over the flue blocks (see BS EN 1858 and seek manufacturer's advice).