As part of a study to assess the efficacy of impregnation for masonry materials, the impregnation of earth substrates with soluble sodium silicate followed by water-based silane/siloxane emulsion was investigated. The treatment was found to be successful in achieving water repellent and consolidation effects for the earth substrates. The water repellent effect is developed by the silane/siloxane emulsion which forms a polysiloxane thin film on the capillary wall surface through siloxane bonds. The water repellent effect is greatly enhanced by pre-impregnation with the silicate. The consolidation of the earth substrate by soluble sodium silicate is caused by the silicate gel formed by crosslinking with the substrate. The water repellent and consolidation effects in the earth substrates have been studied by using water absorption tests and FTIR examination.