XPS Insulation for Swimming Pools

Extruded Polystyrene (XPS) is a high-performance, rigid, closed-cell foam insulation specifically suited for the demanding environment of swimming pool construction due to its exceptional moisture resistance and high compressive strength. These properties ensure the material maintains its thermal performance and structural integrity when installed below ground or under concrete slabs where it is exposed to constant moisture and heavy loads. 

CHARACTERISTICS

• Closed-Cell Structure: The material is manufactured through an extrusion process that creates a homogeneous matrix of millions of tiny, closed cells with no voids. This structure makes it almost completely impervious to water absorption (typically less than 0.7% by volume after long-term immersion) and highly resistant to water vapor diffusion, preventing water ingress which can degrade other insulation types.
• High Compressive Strength: XPS boards offer high load-bearing capacity, typically ranging from 300 kPa to 500 kPa (kilopascals) or higher, depending on the product grade (e.g., Cellecta XPOOL 500kPa). This allows it to withstand the long-term static and imposed loads of a concrete pool structure and the weight of the water without significant deformation.
• Thermal Performance: XPS provides excellent, stable thermal performance over its lifespan, helping to significantly reduce heat loss from the pool to the surrounding ground and lowering heating costs. The typical thermal conductivity (lambda value) is low, often ranging from 0.033 to 0.035 W/mK.
• Durability and Longevity: The material is resistant to rot, decomposition, microorganisms found in soil, and freeze-thaw cycles, ensuring a lifespan of 50 years or more.
• Installation Versatility: Due to its moisture tolerance, XPS can be installed directly in contact with the ground or wet concrete, often without the need for a separate damp-proof membrane (DPM) below the slab, simplifying the construction process. It is lightweight and easy to cut and shape for installation around pool bases and retaining walls. 

APPLICATIONS

XPS boards are specifically designed and used for insulating both the base (floor) and retaining walls of in-ground or above-ground swimming pools. 

• Below the slab: Boards are typically laid on a prepared sub-base before the concrete slab is poured.
• Retaining walls: The boards are installed on the exterior of the pool structure, outside the waterproofing membrane (tanking).