Sound Information

Sound Insulation Approved Document E
The current Approved Document E (“Resistance to the Passage of Sound”) is to be amended, and the proposed amendments were produced in the form of a consultation document dated January 2001 and issued for consultation in April 2000. See below for further information.
As far as sound-resisting separating walls are concerned, the three most common types are as follows.

Wall type 1B Solid Masonry concrete block wall
Current regulations: If building with concrete blocks, the only finish recommended in AD E for this wall type is plaster on both sides of the wall. If plasterboard dry lining is used, you may be called upon to demonstrate by test (see Table 2, Section 3 of current AD E) that the wall gives “adequate resistance to the transmission of airborne sound”.
The wall has to achieve a mass of 415 kg/m² (including plaster and mortar joints).
You must use blocks that extend to the full thickness of the wall. (Two skins of 440 mm x 215 mm x 100 mm blocks laid back to back are not permissible.)
Because of the 415kg/m² requirement, blocks of dimensions 440 mm x 215 mm x 200 or 215 mm would be precluded by the HSE safe-lift limit.
Solution: 440 mm x 215 mm x 100 mm solid Bescrete blocks laid flat to form a 215 mm thick wall, plastered both sides give the required mass.
Proposed amendments to wall type 1B: No change, except that the construction is referred to as wall type 1.1.

Wall type 2B 250 mm cavity masonry concrete block wall
Current regulations: Again, the only recommended finish in AD E for this wall type is 13 mm plaster to both sides of the wall. If plasterboard dry lining is used, you may be called upon to demonstrate by test (see Table 2, Section 3 of current AD E) that the wall gives “adequate resistance to the transmission of airborne sound”.
The wall has to achieve a mass of 415 kg/m² (including plaster and mortar joints).
Solution: Two skins of 440 mm x 215 mm x 100 mm solid Bescrete blocks set 50 mm apart, finished both sides with 13mm of lightweight plaster, give the required mass.
Proposed amendments to wall type 2B: No change other than the 50 mm cavity width is now a minimum recommendation. Construction is now referred to as wall type 2.1.

Wall type 2C 275 mm cavity concrete block wall
Current regulations: This wall type can be either wet plastered or dry lined. The recommended construction in AD E is two skins of lightweight aggregate solid blocks (max density 1600 kg/m³) set 75 mm apart, plastered or dry lined on both room faces.
The wall has to achieve a mass of 300kg/m² (including finishing and mortar joints).
Problem: Solid lightweight aggregate blocks can be expensive.
Solution: Two skins of 100 mm Cellular Bescrete blocks, either dry lined or wet plastered, have consistently demonstrated over a prolonged testing programme that, when tested in accordance with the procedure stipulated in AD E, their performance surpasses by very comfortable margins the sound performance requirements of both the current and proposed amended AD L.

Proposed amendments to wall type 2C
Big changes here: The Draft Approved Document E does not recommend the use of dry lining, referring only to wet plaster finish to both room faces for this wall type.
Further, the testing procedure in the Draft Approved Document E to demonstrate that non-recommended wall constructions give adequate resistance to the passage of airborne sound has been amended to include a low frequency response (Ctr). This is a much more stringent test.
Recognising that house-builders would deem it undesirable to introduce wet trades for this situation, our prolonged testing programme referred to above commenced with the advent of the Draft Approved Document. All tests since that date have been conducted on 100 mm Cellular Bescrete blocks DRY LINED, with flank walls ranging from ultra-light aerated blocks to dense blocks. All testing was conducted by AIRO to the newly required standard (DnT,w + Ctr).
The minimum performance for separating walls detailed in the Draft Approved Document DnTw + Ctr is 45Db. All of our test results exceed this requirement by very comfortable margins.
Test result summary sheets are available on request.

External wall junctions for cavity masonry sound-resisting separating walls
Where the external wall is a cavity wall:
a) the outer leaf of the wall may be of any construction, and
b) the cavity should be stopped with a flexible closer unless the cavity is fully filled with mineral wool.

Where the inner leaf of the cavity external wall is of masonry:
a) the separating wall should be joined to the external wall by one of the following methods:
i) 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.
ii) Tied: the external wall should abut the separating wall and be tied to it with ties at no more than 300
mm centers vertically, to create a homogeneous unit. See diagram.
b) the masonry inner leaf should have a mass per unit area of at least 120 kg/m² excluding finish.
100mm Cellular Bescrete gives the required mass.

Note. The perpendicular faces of the blocks of the inner leaf abut the 440 mm x 215 mm face of the separating wall block.

Other changes
E3 Dwellings and rooms for residential purposes shall be constructed in such a way that they provide reasonable resistance to noise from external sources.

E2 requires reasonable protection against sound within the dwelling.
An internal wall between a room containing a WC and a living room, dining room, study or bedroom (except where the WC is en-suite) shall provide reasonable resistance to sound.
An internal wall between bedrooms or between bedrooms and other rooms, and an internal floor between bedrooms or between bedrooms and other rooms shall give reasonable resistance to sound.

One way of satisfying E2 would be to construct the internal wall to achieve a mass of 120 kg/m² when plastered or dry lined on both sides.
100 mm Cellular Bescrete gives the required mass.