What Is the Structural Composition of Thermal Insulation GRC Exterior Wall Panels? An In-Depth Analysis of Multilayer Composite Structure and Thermal Performance

Insulated GRC exterior wall panels are a high-performance building envelope system integrating decoration, enclosure, and thermal insulation functions. The design of their structural composition directly determines the system's thermal performance, safety, and durability. As the Qinglong Group with 28 years of deep expertise in the GRC field, based on practical experience from multiple ultra-low energy building projects, we believe that high-quality insulated GRC exterior wall panels should adopt a multi-layer composite structure of "decorative panel - transition layer - insulation core - backing layer." Taking our application in a passive building project in northern China as an example, the system achieved a heat transfer coefficient (K-value) ≤0.30 W/(m²·K), far below the national energy-saving standard, and through rational structural design effectively solved core issues such as thermal bridging, condensation, and fire safety, providing an ideal solution for building energy conservation.

The decorative panel layer is the system's appearance and first line of defense, typically using a 10-15mm thick reinforced GRC layer. Its core function is to resist weathering erosion and bear design loads. We use high-performance GRC with compressive strength ≥50MPa and flexural strength ≥18MPa, incorporating hydrophobic agents to keep water absorption below 6%. In a severe cold region project in Shenyang, the panel surface was treated with a self-cleaning nano coating, greatly reducing the risk of surface contamination and erosion caused by freeze-thaw cycles of ice and snow. The reliable connection between the panel and the insulation layer is a structural key. The glass fiber connectors we developed have a thermal conductivity only 1/100 that of metal connectors, effectively cutting off heat conduction paths and preventing thermal bridging.

The insulation core layer is the energy-saving core of the system, and its selection and thickness need to be precisely calculated according to climate zones and energy-saving standards. Qinglong Group typically uses rock wool or thermosetting composite polystyrene board (TEPS) with Class A fire performance, with densities of no less than 140kg/m³ and 35kg/m³ respectively. Based on calculations, we usually add 10%-15% thickness redundancy to address material performance degradation and increase the safety margin. For example, in a project in Harbin, we used 120mm thick water-repellent rock wool with tensile strength perpendicular to the panel surface ≥15kPa, ensuring firm bonding with the panel and backing layer and preventing delamination caused by self-weight or wind pressure after long-term use.

The transition layer and backing layer are key to ensuring the integrity and stability of the system. The transition layer is typically a 3-5mm thick polymer mortar layer embedded with alkali-resistant glass fiber mesh, serving to buffer stress and level the surface, ensuring that the decorative panel does not directly transfer stress to the insulation layer during thermal deformation. The backing layer protects the insulation material and provides an installation substrate, commonly using 6-8mm GRC or fiber cement board. All layers are integrated through specialized composite processes (such as one-shot spray composite molding or high-strength adhesive bonding) and verified through full-scale model testing for wind pressure, thermal performance, and fire resistance limits. This scientific composite construction enables insulated GRC exterior wall panels to achieve excellent thermal insulation performance while also featuring the rich expressive shaping capability and ultra-long durability of GRC materials.