Given its tropical setting, moisture problems are inherent issues found in walls of heritage buildings in Indonesia that require replacement of wall finishing materials with specific properties. This is where heritage science becomes an important approach in the creation of plasters and paints that best resemble its original and/or provide better performance through innovations. Heritage science possesses great potential in improving evidence-led conservation work in Indonesia by incorporating properties of traditional materials with present technology for cultural sustainability that is gaining urgency in the midst of burgeoning population growth. However, despite its growing application for historically significant heritage buildings, the need for preliminary scientific testing is not commonly acknowledged and applied in the adaptive reuse of small-scale heritage buildings in Indonesia. Therefore, this paper studies two UNESCO-funded pilot projects in Jakarta and tracks the role of heritage science throughout their conversion, and aims to evaluate the constraints, by conducting literature studies and eight interviews with various stakeholders involved. It is found that heritage science is yet a key player in Indonesian conservation works, however, it helps uncover material properties of wall finishing materials that best tackle moisture problems in Jakarta heritage buildings.