Improving thermal performance of external load-bearing walls in residential buildings could be the most effective way in reducing energy consumption for air-conditioning purpose in housing sector. The aim of this study is to characterize the already existing external load-bearing walls in the residential buildings, in Iraq, in terms of the thermo-physical properties of the used materials. In addition to that, the assemblies of these materials, i.e. wall configurations have been evaluated regarding the steady-state thermal performance and dynamic thermal admittance parameters. Different scenarios were suggested in order to improve the thermal performance of the existing walls. The effect of the binding material (cement mortar) on the global thermal performance of the wall fabrics has also been investigated by utilizing image analysis to calculate the percentage of this material from whole wall. The results showed that binding material has no significant effect on the thermal performance for the studied walls. Gypsum coating layer can be removed as it has marginal effect on the evaluated properties. It was found that involving two air-cavities (internally and externally) has much effect on the walls thermal performance than other approaches. (C) 2014 Elsevier B.V. All rights reserved.