Multi-layered samples of 1) continuous fiber axially aligned and 2) random oriented mat glass fiber, composites were manually prepared for a fiber content ranging from zero to 20% (vol.). The uniaxially aligned samples displayed linear relations between both normalized elastic modulus and normalized thermal conductivity and fiber content, for axially applied load and heat, flux. For the random malt composite samples, similar results were obtained, with symmetry displayed in the plane of the mat. In both cases, measured axial thermal conductivity permits an evaluation of the axial elastic modulus. The Mathis surface probe used (US patent #5,7951,064) is, demonstrated as a non-intrusive indirect method of obtaining thermal conductivity for heat flux, parallel (i.e. axial or transverse) to the plane of a sample. The method shows potential for use as an in-line monitoring device for the mechanical properties of molded composites.