Cavity Wall Openings with a difference 

The thermal insulation integrity of window and door openings in cavity walls can be increased by using an approach that combines new and traditional methods. 

One approach is to use two separate lintels, with an L- shaped steel (preferably stainless) providing support of the outer skin and a traditional concrete lintel supporting the inner skin. A polypropylene ready-shaped Type C Cavitray locates onto the L-shaped steel and rises upwardly and across the cavity, providing protection to the entire head of the opening. The tray also extends beyond the opening reveals, to cloak whatever method of reveal closing is deployed. The external masonry is laid onto the Cavitray in the usual manner with Caviweeps in a minimum of two perp joints to provide water evacuation. 

With the inner skin rising off the concrete lintel, there is no direct heat-loss connection between skins and the cavity below the sloping tray is open. It is into this open cavity that a shaped Acoustic Stop and Thermal Barrier can be inserted. This new product from Cavity Trays of Yeovil is available in almost any shape – so the designer and contractor can request a profile to suit their specific build detail. 

Acoustic Stops and Thermal Barriers are enveloped within a coloured dpc polythene sleeve that protects the compressible core consisting of rock-wool insulation. When selecting the infill profile, it is usual to add 15 to 20mm to the width dimension, to promote a full and consistent friction fit when compressed. 

Introducing AST Barriers by Cavity Trays of Yeovil can raise the acoustic and thermal integrity of most support arrangements. When used with approved Type C Cavitrays and Caviweeps, every opening can be scheduled for optimum efficiency. The waste factor can be eliminated.

The opportunity to maximise the thermal and acoustic performance of the opening can also extend to the wall reveals and across at sill level. Cavity Trays offers a range of vertical and horizontal closers that permit compliant closing of the cavity whilst providing the requisite dpc and thermal insulating qualities. The specifier can now select models that additionally offer an acoustic benefit as well as an interfacing facility where partial cavity insulation is being used. 

Whether building traditionally or in timber frame construction, the latest products from Cavity Trays enable the designer and contractor to raise levels of comfort and compliancy. 

If your build detail is unusual, Cavity Trays has a fast-track bespoke service offering attention.                 

See page 72 in the new 2011 Technical Manual: ‘Protecting the Building Envelope’ for details of Acoustic Stops and Thermal Barriers