Membrane structures are widely used across Australia as a cost-effective way to provide large shaded areas. This research explores the feasibility of reducing the embodied emissions in such structures by replacing their structural steel components with round timber ‘thinnings’, available as a low-value byproduct from forestry plantation management operations. Roundwood thinning samples from an effluent-irrigated spotted gum plantation are first tested to establish preliminary material characteristics and a design stress grade. Four joints suited for roundwood timber connection are then proposed based on differing levels of steel material requirement, and tested under flexure to establish their rotational ductility and stiffness. From the obtained testing data, a roundwood timber membrane structure is proposed and compared to the existing steel-framed structure using an embodied energy analysis.