Abstract:

Objective: To address critical bottlenecks of timber wall systems in severe cold regions, including inadequate thermal performance (e.g., heat transfer coefficient K=0.692 W·m^?2 K^?1 in light wood frame walls) and significant sound/thermal bridging effects, combined with practical requirements of current energy efficiency and fire safety codes for wall thickness, this study aims to elucidate thermal transfer failure mechanisms in light wood frame and cross-laminated timber (CLT) walls and proposes synergistic optimization strategies for integrated thermal and acoustic performance, thereby advancing high-performance wall solutions for prefabricated buildings in harsh climates. Method: The calibrated hot box method was used to examine thermal resistance (R) on 11 full-scale wall specimens (1.5 m × 1.5 m), and conduct theoretical calculations of thermal performance. Based on the prior airborne sound insulation research data, this study compared and analyzed the impact of staggered design of wood/light steel studs, innovative sound insulation cushion layer [adding rubber pads between wood frames and oriented strand boards (OSB), and adding compressed glass wool strips between light steel frames and gypsum boards (GB)], and composite configurations (CLT walls sheathed with wood frames and filled with glass wool) on the thermal performance of the wall and improves efficiency. Result: The thermal and acoustic performance was synergistically improved. Light wood frame walls with staggered wood studs reduced K to 0.251 W·m^?2K^?1, which is 63.7% lower than that of conventional light wood frame walls. The heat transfer coefficient of light steel frame walls with staggered steel studs was reduced to 0.524 W·m^?2K^?1, which is 47.7% lower than that of the light steel keel composite wall. The heat transfer coefficient of the CLT composite walls (wood frame-sheathed + glass wool) attained K=0.587 W·m^?2K^?1, which is 40.2% lower than that of single-layer CLT walls. Compared with the CLT single-layer wall with only an increase in the number of layers, the CLT composite wall achieved comprehensive breakthroughs in increasing the wall thickness (155 mm vs. 175 mm) and surface density (70.0 kg·m^?2 vs. 91.0 kg·m^?2), and improved the weighted sound insulation (40 dB vs. 37 dB) and heat transfer coefficient (0.587 W·m^?2K^?1 vs. 0.623 W·m^?2K^?1), meeting the dual requirements of thermal and sound insulation performance for building walls. Except for light steel frame walls due to the high heat loss caused by the nail node thermal bridge (penetrating the cladding panel), the theoretical K calculations showed <15% error for other walls, which has high calculation efficiency and accuracy. Conclusion: Sound/thermal bridging in studs critically constrains wood frame wall performance. Staggered framing disrupts vibration transmission paths and elongates thermal conduction channels, mitigating bridging effects. The optimized light wood frame walls with staggered wood studs (208 mm thick, 39.1 kg·m^?2) overcome the insulation-soundproofing trade-off, meeting severe cold region requirements. For single-layer CLT walls, the technical measures of sheathing with light wood frame filled with glass wool proves more efficient than increasing lamina layers.

Key words: timber structure wall, thermal performance, frame optimization, thermal bridging, synergistic enhancement