Two and three dimensional network and continuum models are coupled to evaluate the effective mechanical properties of low-density fibrous composites. Low-density fibrous composites are formed of fibers, binder, and air, and exhibit mechanical properties that strongly depend upon the characteristics of the individual constituents. The effective stiffness and strength are modelled using a fiber network with specific focus on the nature of the joints that connect the individual fibers. In the stiffness calculation, the bonds between fibers are considered rigid, and the primary factors that guide the response of the aggregate are fiber length, diameter, stiffness, and orientation. In strength calculations, the behavior and influence of the binder is more dominant. The model used to predict bulk failure mechanisms is based on both fiber strength and binding node strength. General guidelines and predictions are summarized following a sequence of representative numerical and parametric results.