The Construction Vapour Control Layer ecosystem comprises a defined set of upstream, midstream, and downstream actors that collectively transform raw polymers and reinforcement fabrics into installed vapour barrier systems. Upstream, raw material and component suppliers deliver polyolefin resins, bituminous binders, and reinforcement meshes. Midstream participants—OEMs, technology developers, and system integrators—convert these inputs into finished membranes, embed performance‑enhancing additives, and package products for construction projects. Downstream, distributors and channel partners move the membranes to contractors, while after‑sales service firms provide installation support and warranty management. End users—residential, commercial, and industrial developers—specify and procure the layers as part of building envelope assemblies, creating the final value capture point.