The development of new alternative type of fly ash bricks using the locally available local soil from Ratchaburi province were mixed with fly ash from Kanchanaburi province, where both sources in western of Thailand, is the main purpose of this study. These are compared to the ratchaburi local soil cement bricks without the mixing of western fly ash in different proportions. It is concluded that the addition of western fly ash reduces the thermal conductivity. The compressive and flexural strength decrease when the ratio of western fly ash is more than 30 percentages. However, considering the various factors it can be concluded that appropriate ingredient toward producing the good commercial western fly ash bricks is 5 percentages of portland cement and 30 percentages of western fly ash by weight basis of ratchaburi local soil. The compositions of western fly ash at more than 25 percentages by weight basis of ratchaburi local soil and since up to 14 days of curing time are proved to be economical mixtures for load bearing panels or brick type structural elements according to the Thai Industrial Standard for structural clay load-bearing tile.