Comparative Thermal and Mechanical Characterization of MDF Panels Produced by Hot and Cold Pressing with Different Vertical Density Profiles

The thermal performance of wood-based flooring over underfloor heating depends on panel density and through-thickness structure. This study compared medium-density fibreboard (MDF) panels manufactured by hot and cold pressing, resulting in conventional U-shaped and approximately flat vertical density profiles (VDPs), at nominal densities of 500, 600, and 700 kg m−3. Thermal conductivity, thermal resistance, and heat flux were determined using two specimens per variant (n = 2), while mechanical properties were evaluated using specimens from three independently manufactured panels per variant. Corresponding U- and F-profile panels differed in mean density by only 0.6–2.0%, but exhibited markedly different thermal behaviour. Thermal conductivity was 0.0804, 0.1054, and 0.1199 W m−1 K−1 for the hot-pressed U500, U600, and U700 panels, respectively, compared with 0.0713, 0.0728, and 0.0885 W m−1 K−1 for the corresponding cold-pressed F500, F600, and F700 panels. Thus, the cold-pressed panels exhibited 11.3%, 31.0%, and 26.2% lower thermal conductivity, respectively, than their hot-pressed counterparts. Hot-pressed panels with U-shaped profiles exhibited higher modulus of rupture (MOR) and modulus of elasticity (MOE), whereas cold-pressed panels with approximately flat profiles showed higher internal bond strength (IB). Differences in compressive stress at 10% strain diminished at the highest density. These findings reflect the combined effects of manufacturing conditions and the resulting internal structure, rather than the isolated influence of VDP. The thermal comparisons are preliminary because only two specimens were investigated per variant.