What are the different types of XPS defined in this standard?

The standard classifies XPS into five types based on nominal compressive strength at 10% deformation: XPS 150, XPS 200, XPS 250, XPS 350, and XPS 500 (Clause 3.1).

What is the maximum allowed thermal conductivity (k-value)?

For most common types (density 28-35 kg/m³), the maximum thermal conductivity is 0.029 W/m.K when measured at a mean temperature of 10°C (Table 1).

What is the maximum water absorption for XPS boards under this IS code?

The maximum water absorption is 1.5% by volume when tested as per the specified method (Table 1).

Are there standard sizes for XPS boards?

The standard does not specify fixed sizes but states they shall be supplied in lengths and widths as agreed between the purchaser and supplier, with thickness ranging from 20 to 100 mm (Clause 4.1).

IS 11206

: 1985

Specification for extruded polystyrene (XPS) for thermal insulation

CurrentSpecializedSpecificationBIMMaterials Science · Insulation Materials

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This standard specifies the requirements, testing methods, and sampling procedures for rigid extruded polystyrene (XPS) boards intended for thermal insulation. It classifies XPS into five types based on compressive strength and details mandatory physical properties such as density, thermal conductivity, water absorption, and dimensional stability. The code serves as a benchmark for manufacturers and for quality assurance in construction projects.

Specifies requirements for extruded polystyrene (XPS) products used for thermal insulation.

Quick Reference Values

Maximum Thermal Conductivity (at 10°C mean temp)0.029 W/m.K

Minimum Compressive Strength (Type XPS 200)200 kPa at 10% deformation

Nominal Density (Type XPS 200)28 kg/m³

Maximum Water Absorption1.5% by volume

Maximum Water Vapour Transmission4.5 ng/Pa.s.m

Minimum Closed Cell Content90 %

Maximum Dimensional Change (at 70°C, 48h)3.0 %

Practical Notes

Ensure material is protected from prolonged direct sunlight (UV exposure) which can degrade the surface, a factor not covered in detail by this standard.

While the code specifies minimum compressive strength, select a higher grade for applications with significant loads, such as inverted roofs or under-slab insulation.

Always verify the manufacturer's test certificate against the requirements of Table 1, paying close attention to the thermal conductivity (k-value) which is critical for performance.