What is the primary difference between EPS grades like EPS 15, 20, and 30?

The grade number indicates the nominal density in kg/m³. Higher density generally provides greater compressive strength but does not necessarily mean better thermal insulation. (Refer to Table 1 for specific properties).

What is the maximum thermal conductivity (k-value) allowed for EPS 20?

For EPS 20 grade, the maximum thermal conductivity is 0.038 W/(m.K) as per Table 1.

Is standard EPS waterproof?

No, it is water-resistant. The maximum water absorption by volume is specified as 2.0% after 7 days of submersion, according to Table 1.

What are the standard dimensional tolerances for an EPS sheet?

For length and width, the tolerance is ± 2 mm. For thickness, it is ± 1 mm, as per Table 2.

IS 9428

: 2018

Expanded Polystyrene (EPS) for Thermal Insulation - Specification

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This standard specifies the requirements for Expanded Polystyrene (EPS) boards and blocks used for thermal insulation purposes in buildings, cold storage, and HVAC applications. It classifies EPS based on density and outlines mandatory physical properties, including thermal conductivity, compressive strength, dimensional stability, and water absorption, along with test methods and dimensional tolerances.

Specifies requirements for expanded polystyrene (EPS) boards and blocks used as thermal insulation materials.

Quick Reference Values

Max thermal conductivity for EPS 150.042 W/(m.K)

Min compressive strength for EPS 15 (at 10% deformation)80 kPa

Max thermal conductivity for EPS 200.038 W/(m.K)

Min compressive strength for EPS 20 (at 10% deformation)120 kPa

Max water absorption for all grades2.0 % by volume

Length/Width tolerance± 2 mm

Thickness tolerance± 1 mm

Practical Notes

EPS is vulnerable to UV degradation and must be protected from sunlight during storage and prior to being covered in the final assembly.

Ensure compatibility with adhesives and coatings, as certain solvents can dissolve or damage EPS.

While a 'Self-Extinguishing' (SE) grade exists, EPS is combustible and must be handled and installed according to fire safety norms, often requiring a thermal barrier like gypsum board.