Celotex Isover

Insulation for Masonry Cavity Separating Wall

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The primary purpose of a separating (Party) wall is to provide acoustic separation for airborne sound between two adjacent dwellings, thereby improving the acoustic comfort of those living within both dwellings. The minimum permitted acoustic specifications are defined by Approved Document E (England & Wales) and Section 5 (Scotland), although it is often recommended to improve on this where possible. 

One of the methods to demonstrate achieving this is to use Robust Details, alternatively an acoustician can be tasked with verifying the design of a separating floor.

The insulation of choice for masonry cavity separating (Party) walls is typically a glass mineral wool (GMW) roll or slab. ISOVER RD Party Wall Roll can be installed as part of the separating (Party) wall construction within the central cavity between the two lines of blockwork to provide the level of sound reduction required according to Approved Document E (England & Wales) and Section 5 (Scotland).

Another important benefit of certain specifications and then correctly installing insulation in the cavity is that it can help contribute to a zero effective U-value in SAP* for this wall, reducing energy usage and making compliance with Building Regulation easier.

*as per RDPWR PDS on zero-effective U-value in SAP

The building detail is for illustrative purposes only. It does not constitute advice and should not be relied upon.


Insulation products to consider
Product Name Thickness Range Sizes Lambda BBA
ISOVER RD Party Wall Roll 75-150mm Width 2 x 455mm, Length 4000-8500mm 0.036 W/m.K Tick Icon