J.A. TINKER, University of Leeds
A.O’ROURKE. The Nottingham Trent University

Although the UK Building Regulations state that the mortar joint can be ignored when the U-value of a wall is calculated, by doing this, the U-values quoted for the heat loss through an external wall may be in excess of thai allowed. When the mortar joint is included in the calculation, a standard value for thermal conductivity of the mortar of 0.84 W/mK is often used despite the many mortar mixes used. To assess the variation that occurs over the different designations of mortar, the thermal conductivity of twenty different mortars has been measured. The results show a spread in excess of 35%.