Designing new addition to heritage buildings an aspect of the adaptive reuse process is a nuanced and challenging task. Designers must adhere to international agreements, charters, and regulations governing preservation and conservation to ensure all interventions align with these standards. The paper aims to explore and consolidate the design principles and guidelines for creating contemporary additions to historic structures within the framework of adaptive reuse. The research employs an in-depth analysis of relevant literatures, examining studies focused on the adaptation process of heritage buildings and the associated design processes for new additions. The findings aim to distill and highlight general principles for designing new contemporary additions to host historic buildings, providing a comprehensive and structured review of this critical subject.