Abstract: This study studied the Mixed Asphalt Solar Water Heater (MASWH) integrated on the roof top. This solution can reduce ceiling heat gain into the room. Both reference house and house-integrated with MASWH have dimension 1 m width, 1 m length and 1 m height. The MASWH has a thickness of 0.05 m, width of 0.5 m and a length of 1 m. One house equipped with MASWH on the roof top to test in experiments while the other house was served as reference. The roof was inclined at 30° to the horizontal. The experimental result showed that the attic temperature and room temperature. The house-integrated with MASWH could reduce attic temperature of 3°C and room temperature of 4°C, respectively. The percentage of room temperature decreased in the range of 7-10%. Heat gain reduction of the house-integrated with MASWH become better than reference house about 5-12 Wm2 and the maximum of outlet water temperature was 52.8°C. Obviously, installing MASWH on the roof top can reduce heat transfer. The economic value was evaluation as the payback period and the result showed that 2.5 years.