Despite the numerous advantages of using natural materials, such as fast-growing, living, and earthen materials, their widespread application in the construction industry remains limited. This research presents a perception survey, which investigates stakeholders’ perceptions regarding the market, regulatory barriers, and educational barriers, exploring experiences, motivations, and attitudes toward the adoption of natural materials in construction projects. The results capture variations in current practices and identify patterns for future directions, analyzed in a comparative manner to assess two geographical regions: Europe and North America. The results show that contractor availability, a lack of professional knowledge (mostly in Europe), and cost-to-value perceptions (mostly in the USA) are key barriers to adopting natural materials. The lack of awareness among construction professionals regarding technical aspects highlights the need for targeted training, while the lack of regulatory distinction between living and earth-based materials underscores the need for harmonized policies. By elucidating stakeholders’ perspectives and identifying key challenges, this research aims to inform policymaking, industry practices, and research initiatives aimed at promoting the use of a wider lexicon of construction materials. Ultimately, this study hopes to facilitate the development of strategies to overcome scalability challenges and accelerate the transition toward their implementation in mainstream projects.

European policy agendas increasingly position the built environment as a priority field for deep decarbonization and resource efficiency. This paper investigates how bio-based and regenerative materials can support circular construction through the development and preliminary assessment of a timber-mycelium hybrid box-based infill unit for prefabricated timber building systems. The methodology combines targeted literature review, material exploration and iterative prototyping within a material-driven, bottom-up framework. The unit reinterprets sheet-based CNC plywood panel logics as an assembly scaffold and integrated permanent formwork for mycelium-based composite growth, enabling dry assembly and potential selective replacement within timber structural frames (e.g., CLT). Prototyping confirms the feasibility of a compartmentalized plywood frame that supports more uniform colonization and repeatable fabrication. A comparative screening LCA benchmarks the hybrid unit against a conventional insulation proxy, indicating lower embodied impacts under the tested baseline assumptions and highlighting key sensitivities, particularly drying/deactivation electricity. Overall, the study provides proof of concept for circular envelope components and a transparent decision-support workflow for early-stage design iteration.