The use of commercially available chemical consolidants (hexamethylene diisocyanate (HDI) - derived polymers and silane esters) has been shown to increase the compressive strength of adobe and other natural building materials. Laboratory and field testing of chemically-treated adobe and sand-clay mixtures have also revealed an enhanced resistance to disintegration by water. In HDI-treated materials this resistance to disintegration is attained without a significant loss of porosity. Because porosity is not lost and the adobe can still transmit water, the uptake of water by capillary rise is less destructive than for an adobe whose surface is sealed against moisture penetration.