The effect of exposure direction and inclination on the runoff rates of both zinc and copper has been studied by field exposures on model roofs. Runoff rates decrease with higher inclinations from horizon and are higher for exposures directed towards the prevailing wind direction. At a given pollution concentration, the metal runoff is largely governed by the precipitation volume impinging on the surface. In this study the field exposure results were compared to laboratory tests on zinc and copper panels with different inclinations. Current literature mainly describes runoff rates for zinc and copper panels inclined 45 o facing south.Calculations of the average runoff rate using the runoff rates obtained on the model roofs as well as market information show that the effect of inclination, orientation and degree of sheltering are important parameters to consider while estimating runoff rates from existing buildings.