The current study presents the development and optimisation of foam glass manufactured from recycled glass shards and expanded ground perlite, targeting enhanced structural and thermal performance for sustainable building applications. By investigating various particle size fractions (“125 μm”, “250 μm”, “500 μm”) and sintering temperatures (800–850 ◦C), we achieved a foam glass with superior compressive strength and uniform porosity. Notably, samples utilising a homogeneous 500 μm particle fraction sintered at 850 ◦C exhibited the highest compressive strength of 2.17 MPa, coupled with open porosity uniformity and stable structural matrix formation. Density values in this fraction decreased from 321 to 263 kg/m3, indicating effective foaming and well-developed open porosity that balances mechanical integrity and thermal insulation. The optimised thermal regime minimised crystalline phase formation, preserving low thermal conductivity and mechanical stability. Compared to heterogeneous composites, the homogeneous fractions demonstrated significantly improved strength-to-porosity ratios, ensuring predictable mechanical performance and competitive thermal insulation properties. These findings underline the material’s potential as a cost-effective, environmentally friendly insulation solution that meets or exceeds existing standards, with promising applications in energy-efficient construction.