Building adaptation projects may involve hazardous and toxic substances hidden in the building materials. These substances pose dangers to health and safety, disturbing the environment and affecting the projects’ turnover. Literature reviews on building adaptation and building materials information management found that vital information are seldom available. This study determines the awareness and knowledge of stakeholders in Malaysian building adaptation projects on the required building materials information. Analysis of interviews with 16 experienced stakeholders revealed the lack of awareness and information on existing building materials that may contain hazardous and toxic substances. Thus, building material information is critically required for future sustainability.