Supporting an opening within a cavity wall using separate lintels that do not connect and thus do not have a linked opportunity to conduct heat loss, can help improve the overall thermal performance of the structural opening. This arrangement when accompanied with a self-supporting Cavitray and an infilling profiled Cavisock promotes performance levels not possible with most conventional approaches.
Lintels are assessed for their effect on the thermal performance of a building with the linear thermal transmittance expressed in terms of Psi Values (ψ). Focusing on eliminating conductive connection from one masonry skin to the other can assist in achieving compliance with Part L and the Code for Sustainable Homes.
Outer skin support is provided by a stainless or galvanized steel L section, within which fits a preformed Type C Cavitray. The tray is self-supporting and does not require building into the inner skin. The shape of the tray and its relationship with any cavity insulation can be selected pending whether square or angled integration is preferred. Support of the inner skin is provided by a steel or concrete lintel. The void between lintels and under the angled tray upstand is in-filled with a thermal-acoustic Cavisock, whilst above the tray any cavity infill insulation may rise unobstructed.
Compared with a typical lintel with a value in the range of 0.23 to 0.5 W/mK, this arrangement can promote a value of up to 0.05 W/mK. A significant contribution to a buildings performance in respect of the Fabric Energy Efficiency Standards (FEES) is possible with this detail.