Consolidation of deteriorated old rooftiles for the purpose of reuse was studied, and a 35% solution of methyl triethoxy silane in a mixed toluene/methanol solvent (SS-101) with the aid of a catalyst was found effective. Old rooftiles were immersed in SS-101 for about two hours and then dried in air for more than two weeks. The consolidated rooftiles treated in this way showed a marked decrease in water absorption as determined by a water immersion test, and very good durability as determined by repeated boiling and freezing tests and by freeze-thaw test. The treatment did not cause any significant increase in the flexual strength. See 18-1519. -- AATA