Experimental and numerical studies on the thermal performance of structural insulated panel splines

This paper presents the experimental and numerical studies on the thermal performance of structural insulated panel (SIP) splines. Typical SIPs are comprised of two structural facings of oriented strand board (OSB) and an insulation layer of expanded polystyrene (EPS). Splines with steel nails used to connect the panels reduce the thermal performance of the SIP wall. The thermal transmittance of three types of splines commonly used in SIP wall was measured experimentally. Then the finite element model of an affected area unit of the spline was established, and a parametric study was conducted to investigate the effect of the materials' thermal conductivity, insulation layer thickness, nail spacing, and nail diameter on the thermal performance of the spline. The insulation layer was found to be the most significant factor on the thermal performance of the spline, and weakened the effect of the thermal bridge caused by nails. The nail had only a slight effect on the thermal performance of the spline. The thermal performance of the spline could be improved by reducing the materials’ thermal conductivity, increasing the thickness of the insulation layer and the nail spacing, and reducing the nail diameter. •The effect of design parameter on the thermal performance of structural insulated panel splines was investigated.•Conductivity of insulation had a more significant effect on thermal performance of spline with less thermal bridge effect.•The nail had a slight effect on the thermal transmittance of the spline.•Provided a reference for the thermal design of structural insulated panel buildings.