The thermal conductivity of a building material is a necessary parameter in estimating the cooling load of a building. Cooling load estimates are quite important in selecting building materials especially in hot-climate areas as in Qatar or the Middle East. Commercial equipment for measuring thermal conductivity are quite expensive, and usually not available in the local market. This paper presents a cheap method for measuring thermal conductivity. An apparatus was build and tests were conducted to measure the thermal conductivity of a thennostone brick, a concrete brick, and a red-clay brick. Results of the tests have yielded a conductivity of 0.383 W/(m °C) for the thennostone brick, 1.443 W/(m°C) for the concrete brick, and 0.633 W/(m °C) for the red-clay brick.