Wall Types

Separating walls can be classified into 4 types for the purposes of Part E of the Building Regulations:

Wall type 1 – Solid masonry construction with a plaster finish. The mass per unit area of the wall will largely determine the resistance of airborne sound.

Wall type 2 – Solid masonry construction with dry lining. The resistance of airborne sound will be dependant on the mass of the masonry construction, the absorption ability of the mineral wool and the isolation of the drylining.

Wall type 3 – Cavity masonry construction with a plaster finish. The mass per unit area of the two leaves of the wall in addition to the degree of isolation achieved by the cavity will determine the resistance to airborne sound. The isolation achieved by the cavity can be affected by connections (i.e. wall ties) and the width of the cavity.

Wall type 4 – Timber framed walls with absorbent material. The absorption in the cavity between frames, the isolation of the timber frames and the mass per unit area of the leaves will determine the level of resistance to airborne sound.

Diagram HE3 - Types of wall - Extract from TGD E

Flanking Provisions

Junction between separating walls and other building

Table 4 of Technical Guidance Document E provided below details the construction details which should be used at the junction of separating walls and other building elements depending on the wall type being used. Compliance with the required details should be achieved to ensure adequate control of flanking transmission is achieved.

Table HE4 - Reference table of illustrations provided on separating wall junctions - Extract from TGD E

Corridor Walls

The details provided in this document relating to separating walls should be used between dwellings and common corridors in order to ensure flanking transmission is controlled and to provide the required sound insulation.

Entrance doors opening onto a common area

The entrance door to a dwelling that opens into a common corridor can prove to be a weakness in the level of sound insulation achieved along the separating wall. To ensure the maximum level of sound resistance is achieved the door set should be fitted tightly into the wall opening. The door should have a minimum mass per unit area of 25 kg/sqm or a sound reduction index of no less than 29 dB Rw when tested in accordance with IS EN ISO 717. The door should be provided with an appropriate perimeter seal.

Noise from services

Noise annoyance can be caused to dwelling occupants from building service installations, such as lifts, air con etc and drainage pipes that run the height of the building. During the design stage the location of services and their individual design should be carefully considered so as to minimise the impact of the noise from these elements on occupants.

The internal layout of the dwellings should be designed such that rooms where noise is created are located away from rooms where noise would eb detrimental i.e. kitchen/living rooms should be located away from bedrooms where possible.

Additional guidance on sound reduction is available from BS 8233: 2014 – Guidance on sound insulation and noise reduction for buildings.

Should a lightweight structure be used in the construction of the dwellings additional consideration should be given to the support of noisy plant, it may be advisable to support plant on a separate rigid structure to minimise noise production.

Wall Type 1 – Solid Masonry/Concrete with Plaster Finish

The diagrams below, which are provided in Technical Guidance Document E provide the construction details for all the relevant elements to ensure the appropriate level of airborne sound resistance is achieved. The resistance to airborne sound will largely depend on the mass per unit are of the wall.

Diagram HE4 - WT 1 Solid masonry / concrete with plaster finish - Extract from TGD E

Diagram HE5 - WT 1A Solid masonry with plaster finish - flanking requirements at an external (flanking) wall - Extract from TGD E

Diagram HE6 - WT 1 Solid masonry / concrete with plaster finish - position of openings in an external (flanking) wall - Extract from TGD E

Diagram HE7 - WT 1 Solid masonry with plaster finish - key junction details - Extract from TGD E

Wall Type 2 – Solid Masonry with Dry Lining

For this wall time the resistance to airborne sound is largely dependant on the mass of the core mass, the adsorption of the mineral and appropriate isolation of the dry lining. The diagrams below, which are provided in Technical Guidance Document E provide the construction details for all the relevant elements to ensure the appropriate level of airborne sound resistance is achieved.

Diagram HE8 - WT 2 Solid masonry with dry lining - specification - Extract from TGD E

Diagram HE9 - WT 2 Solid masonry with dry lining - flanking requirements at an external (flanking) wall - Extract from TGD E

Diagram HE10 - WT 2 Solid masonry with dry lining - position of openings in an external (flanking) wall - Extract from TGD E

Diagram HE11 - WT 2 Solid masonry with dry lining - key junction details - Extract from TGD E

Wall Type 3 – Cavity Masonry Wall with Plaster Finish

The diagrams below which are provided in Technical Guidance Document E provide the construction details for all the relevant elements to ensure the appropriate level of airborne sound resistance is achieved. The resistance to airborne sound for walls of this type is dependent on the mass per unit area of the wall leaves and on the degree of isolation the cavity provides. It is important to note that the isolation is affected by connections between the wall leaves i.e. wall ties and the width of the cavity.

Diagram HE12 - WT 3 Cavity masonry with plaster finish - specification - Extract from TGD E

Diagram HE13 - WT 3 Cavity masonry with plaster finish - flanking requirements for an external (flanking) wall - Extract from TGD E

Diagram HE14 - WT 3 Cavity masonry with plaster finish - flanking requirements in staggered external wall - Extract from TGD E

Diagram HE15 - WT 3 Cavity masonry with plaster finish - position of openings in an external (flanking) wall - Extract from TGD E

Diagram HE16 - WT 3 Cavity masonry with plaster finish - key junction details - Extract from TGD E

Wall Type 4 – Timber Framed Wall with Absorbent Material

The resistance to airborne sound for walls of this type is dependent on the mass per unit area of the wall leaves the isolation of the frames and the absorption in the cavity between the timber frames. The diagrams below which are provided in Technical Guidance Document E provide the construction details for all the relevant elements to ensure the appropriate level of airborne sound resistance is achieved.

It is important to ensure that timber frame dwellings are constructed in compliance with IS 440 – Timber frame construction, dwellings and other buildings.

Diagram HE17 - WT 4 Timber framed walls with absorbent material - specification - Extract from TGD E

Diagram HE18 - WT 4A Twin leaf timber frame without sheathing - flanking requirements for an external (flanking) wall - Extract from TGD E

Diagram HE19 - WT 4A Twin leaf timber frame without sheathing - key junction details (1 of 3) - Extract from TGD E

Diagram HE20 - WT 4A Twin leaf timber frame without sheathing - key junction details (2 of 3) - Extract from TGD E

Diagram HE21 - WT 4A Twin leaf timber frame without sheathing - key junction details (3 of 3) - Extract from TGD E

Diagram HE22 - WT 4A Twin leaf timber frame without sheathing - services and sockets in separating walls - Extract from TGD E

Diagram HE23 - WT 4B Twin leaf timber frame without sheathing - flanking requirements for an external (flanking) wall - Extract from TGD E

Diagram HE24 - WT 4B Twin leaf timber frame without sheathing - key junction details (1 of 3) - Extract from TGD E

Diagram HE25 - WT 4B Twin leaf timber frame without sheathing - key junction details (2 of 3) - Extract from TGD E

Diagram HE26 - WT 4B Twin leaf timber frame without sheathing - key junction details (3 of 3) - Extract from TGD E

Diagram HE27 - WT 4B Twin leaf timber frame without sheathing - services and sockets in separating walls - Extract from TGD E

Section 3: Separating Walls and associated Flanking Construction Details