In French Guiana, the development of bio-circular value chains to convert residual biomass into insulation fiberboard represents a promising opportunity for energy-efficient construction. The objectives of this work are to identify and characterize resources of interest and discuss the relationships between fiber properties, manufacturing parameters, and fiberboard performance. Five wood and bark fibers were fractionated from residual biomass of 4 local species, and their fractions analyzed by: laser granulometry, thermal gravimetric analysis (TGA), and pyrolysis combustion flow calorimetry (PCFC). Fiberboards were produced using a thermomechanical process and their microstructure, thermal, and sorption properties were characterized by X-ray tomography, hot plate technique, and dynamic vapor sorption (DVS). Morphological analysis showed that large and elongated wood fractions form thick and cohesive fibrous networks, while small-sized bark fractions are more difficult to process, requiring more compaction and synthetic fiber additives due to lower natural self-adhesion. Despite processing difficulties, bark fiberboards showed the best insulation performance, comparable to commercial reference products. TGA and PCFC tests revealed that bark fibers have better thermal stability and fire behavior compared to wood, and a stronger water affinity compared to wood fractions, highlighting the need for further investigations of durability performance in tropical conditions in the long term, but also a potential interest for humidity regulation.