Cavity wall (contaminated land) gas barriers usually rise not less than 150mm in the cavity and often have to rise considerably more as they rely on support by being built into the inner skin – and coursing is rarely at the ideal height.
Cavity Trays of Yeovil – the only UK cavity tray manufacturer awarded European Technical Approval – has now made construction easier, by producing what is termed a Rise and Fall Barrier.
Rise and Fall Barriers are self-supporting and offer the convenience of starting and finishing at the same level. Rise and Fall Barriers support themselves, so seeking an inner skin mortar bed to hold the barrier to shape is not required.
Incorporated within the exterior cavity walls at ground floor level, Rise and Fall Barriers permit a more easily-managed build sequence and compact protective arrangement, and if the floor construction configuration requires the barrier to terminate at any intermediate or lower position, such levels are all possible.
Linking of barrier and oversite membrane is more straightforward. Additionally, the option to have an extended barrier section projecting across the oversite permits horizontal lapping and sealing on the flat, considerably simplifying the build sequence programming.
Rise and Fall Barriers are supplied in long lengths with internal and external angles and a range of stepped links. Once bedded in position, sealing capping profiles that straddle abutting sections ensure water and gas-tight continuity. Raising of the cavity wall may continue with the usual task of providing support at higher level completely eliminated. This elimination of building into the inner skin at higher level also means any partial fill cavity insulation is not dissected above and below at this level, so thermal integrity is maintained.