SEPARATING WALLS (NEW BUILDINGS)
2.35 Wall type 1.3 Brick, plaster on both room faces (see Diagram 2-4)
minimum mass per unit area including plaster 375 kg /m2
13 mm plaster on both room faces
bricks to be laid frog up, coursed with headers
Example of wall type 1.3
The required mass per unit area would be achieved by using
- 215 mm brick
- brick density 1610 kg /m3
- 75 mm coursing
- 13 mm lightweight plaster (minimum mass per unit area 10 kg /m2) on both room faces
This is an example only. See Annex A for a simplified method of calculating mass per unit area. Alternatively use manufacturer’s actual figures where these are available.
Diagram 2-4: Wall type 1.3
Junction requirements for wall type 1
Junctions with an external cavity wall with masonry inner leaf
2.36 Where the external wall is a cavity wall:
- the outer leaf of the wall may be of any construction, and
- the cavity should be stopped with a flexible closer (see Diagram 2-5) unless the cavity is fully filled with mineral wool or expanded polystyrene beads (seek manufacturer’s advice for other suitable materials).
2.37 The separating wall should be joined to the inner leaf of the external cavity wall by one of the following methods:
- Bonded. The separating wall should be bonded to the external wall in such a way that the separating wall contributes at least 50% of the bond at the junction. See Diagram 2-6.
- Tied. The external wall should abut the separating wall and be tied to it. See Diagram 2-7. Also, see Building Regulation Part A - Structure.
2.38 The masonry inner leaf should have a mass per unit area of at least 120 kg /m2 excluding finish. However, there is no minimum mass requirement where there are openings in the external wall (see Diagram 2-8) that are:
- not less than 1 metre high, and
- on both sides of the separating wall at every storey, and
- not more than 700 mm from the face of the separating wall on both sides.
2.39 Where there is also a separating floor then the requirement for a minimum mass per unit area of 120 kg/m2 excluding finish should always apply, irrespective of the presence or absence of openings.
Resistance to the passage of sound Approved Document E 20