Robust Details E-WM-23 and 24 are now available for a high-performance cavity separation wall construction using H+H aircrete blocks.  The fully filled cavity solutions, designed to address the thermal insulation requirements of Part L, have the added benefit of providing a high acoustic performance which exceeds the requirements of Part E of the Building Regulations sufficiently to attract 3 credits under the Code for Sustainable Homes.

H+H Standard Grade, High Strength Grade and Super Strength Grade materials are all suitable for use in the construction of E-WM-23 and 24 separating walls and flanking walls - H+H Solar Grade may also be used in flank walls. This means a reduction in block types needed per project and a reduction in the margin for error and waste on site. 

A suitable Robust Detail E-WM-23 or 24 construction comprises two leaves of H+H Standard Grade, High Grade or Super Grade Strength aircrete blocks with traditional mortar or Celfix Thin – Joint mortar, with a minimum 100mm cavity between.  Detail 23 is with a 100mm cavity fully-filled with Superglass Party Wall Roll, whilst Detail 24 is with Isover RD Party Wall Roll.

Both solutions only require that the separating wall construction is finished with a conventional 8 kg/m2 plasterboard on dabs. This eliminates the need for the additional process of applying a wet parge coat to each side of the wall, as commonly used with other masonry separating walls.

In addition, the use of H+H’s aircrete in separating and flanking walls enables capitalisation on the significant savings from reduced heat loss at non-repeating linear bridges. 

Linear thermal bridging is a major source of heat loss and the use of aircrete party walls has a major benefit in reducing this by leakage through the masonry into the roof, floors and external walls.  As U-values get even lower heat loss from junctions can now account for as much as 30% of the heat lost through the fabric of a building.