If you have failed you precompletion testing on a party wall, remedial treatments can be applied to party walls between residential spaces in order to improve airborne sound insulation and achieve a pass. These are many treatments that can be applied to the wall which include cavity infill insulation, wet and dry lining as well as independent linings.
On existing masonry and blockwork walls may present poor airborne sound insulation performance due to various anomalies in the dry lining finishes (open mortar joints, uneven blockwork façade etc.).
The application of a parge, or render coating to the wall’s face before dry-lining contributes significantly towards a successful sound insulation test. This is due to the fact that this procedure seals any open joints and increases the mass of the wall. The wet treatments are usually composed of a cement-sand mix. Gypsum-based coatings are also available off the shelf.
A parge coated wall is often finished with a plasterboard layer on dabs. The parge coat should be scratch finished or applied unevenly in order to create a better bonding surface for the dry-lining dab. The parge coat should never be stronger than the blockwork on which it is applied, since mortar joints may crack during the drying.
Boards with mineral wool backing layer
Walls can also be lined with boards which employ a compressed mineral wool backing layer. These are best used with 8mm render or parge coat when combined with a blockwork wall and vary in thickness (usually between 32mm and 50mm).
This type of treatment performs well when installed on the residential side of a separating wall to a communal area (hallway, corridor, stairwells).
Independent wall treatments
Independent wall constructions provide a combination of isolation, resilience and absorption, offering an excellent approach to improving the sound insulation of a wall.
The independent lining is usually a metal or timber frame set off from the existing wall. The size of the metal or timber studs depends on a number of factors such as floor to ceiling height and structural loads on the wall.
The independent wall must not come in direct contact with the existing wall. This is why a minimum separation of 30mm is always advised. However, it is always connected to the floor and ceiling by a set of channels. In order to further improve the sound insulation performance, a layer of mineral wool (minimum 50mm) should be installed within the actual frames and the finish should incorporate one or two layers of dense plasterboard.
The aforementioned wall treatments should be incorporated into an overall acoustic strategy and should never be constructed without first consulting your acoustician.
If you would like more information in regards to acoustic design on your project, please contact us at firstname.lastname@example.org or call Darren direct on 07775623464.
Alternately, if you would like more information on preparing your building for sound testing, please visit our checklist page.