The market share for IBS in Thailand is growing very rapidly due to labour shortage and high interest rate. The major IBS are prefabricated wall and slab. The former system has been used for more than 20 years ago while the latter system has been used in the market for 10 years. Another system that gain popularity in the recent year is the autoclave aerated concrete which is a lightweight brick, known locally as Superblock. The annual growth rate of IBS in Thailand was about 30% in 1996. There are about 20 IBS suppliers in the market (Thai Farmers Research Center, 1996).