Lightweight timber frame party walls between semi-detached or terraced houses and flats and party floors between flats comfortably meet the current requirements of building regulations for sound insulation.

This is despite the traditional view of many design professionals that building mass is the only way to provide high sound insulation and the fact that many acoustical textbooks still reflect this view.

Regulatory values for the minimum acoustic performance are defined for both airborne and impact sound insulation for separating (or party) elements between flats or dwelling houses.

For separating walls these values are:

	England & Wales	N.Ireland & Scotland
Airborne insulation	Min. 52 dB	Min. 53 dB
Impact transmission	No requirement	No requirement

 
Standard party wall construction achieves in excess of 64 dB airborne sound insulation. Consequently, there have been few complaints from occupants concerning the acoustic performance of timber frame party walls.

For party floors the values are:

	England & Wales	N.Ireland & Scotland
Airborne insulation	Min. 51 dB	Min. 52 dB
Impact transmission	Max. 61 dB	Max. 62 dB

 
where higher airborne sound insulation and lower impact sound transmission (caused by footsteps, or an item being dropped, perhaps) means better performance.

Standard timber party floors incorporating a layer of 19mm plasterboard below the floor decking, 'floating' on a glass wool slab, exceed the minimum regulatory requirements by providing 54 dB airborne insulation and 59 dB impact transmission.

However TRADA has demonstrated that by 'de-coupling' the ceiling from the floor joists a significantly enhanced acoustic performance can be achieved, up to 63 dB airborne and down to 45 dB impact transmission. These enhanced floor designs easily exceed all current and proposed regulatory requirements.

For further information see the TRADA publication Acoustic performance of party walls and floors in timber framed buildings available from www.trada.co.uk