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IS 9428:2018 is the Indian Standard (BIS) for expanded polystyrene (eps) for thermal insulation - specification. 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.
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
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.
Provides a framework and general requirements for various rigid cellular plastic insulation types, including EPS.
Key Differences
≠IS 9428 classifies EPS primarily by nominal density (e.g., SE, N, HD), whereas EN 13163 uses a performance-based designation code (e.g., CS(10)100 for compressive strength) and ASTM C578 uses 'Types' based on physical properties.
≠Fire performance classification is fundamentally different. IS 9428 uses 'Normal (N)' and 'Self-extinguishing (SE)' based on a simple flammability test. EN 13163 uses the comprehensive Euroclass system (A1 to F), and ASTM C578 references specific test results like Flame Spread Index from ASTM E84.
≠EN 13163 and ASTM C578 include detailed requirements for long-term properties like compressive creep and long-term water absorption by diffusion, which are not explicitly specified in IS 9428.
≠The system for dimensional tolerances varies. IS 9428 provides fixed maximum tolerances, while EN 13163 specifies different tolerance classes (e.g., L1/L2/L3 for length, T1/T2 for thickness) allowing for different levels of product precision.
Key Similarities
≈All standards cover factory-made, rigid boards of expanded polystyrene (EPS) as the core material.
≈The primary intended use across all standards is for the thermal insulation of buildings.
≈Key physical properties such as compressive strength (measured at 10% deformation), thermal conductivity, and water absorption are specified requirements in all standards, forming the basis of product evaluation.
≈The fundamental test methods for determining core properties like thermal conductivity (using guarded hot plate or heat flow meter) and compressive strength are based on similar principles and ISO-aligned methods.
Parameter Comparison
Parameter
IS Value
International
Source
Classification Basis
Primarily by nominal density (15, 20, 24, 30 kg/m³ etc.) and flammability (SE/N).
By declared performance levels for various properties (e.g., compressive strength, dimensional stability).
EN 13163
Compressive Strength (Lowest Density/Type)
Min 70 kPa (for SE Grade, 15 kg/m³)
Min 69 kPa (for Type I)
ASTM C578
Thermal Conductivity (Lowest Density Grade, at 10°C)
Max 0.038 W/(m·K) (for SE Grade, 15 kg/m³)
A typical declared value (λD) for an equivalent product is 0.038 W/(m·K).
EN 13163
Water Absorption (by volume, short term total immersion)
Max 2.0% (for SE Grade, after 7 days)
Max 4.0% (for Type I)
ASTM C578
Dimensional Stability (Lengthwise, at 70°C)
Max 1.0% change (after 48 hours)
≤ 2.0% change (Level DS(70,-)2) (after 48 hours)
EN 13163
Flexural Strength (Lowest Density/Type)
Min 120 kPa (for SE Grade, 15 kg/m³)
Min 172 kPa (for Type I)
ASTM C578
Fire Performance
Categories: 'Normal' or 'Self-extinguishing' (SE)
Euroclass System: A1, A2, B, C, D, E, F (EPS is typically Class E).
EN 13163
⚠ Verify details from original standards before use
Key Values7
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
Tables & Referenced Sections
Key Tables
Table 1 - Physical Requirements of Expanded Polystyrene for Thermal Insulation
Table 2 - Dimensional Tolerances
Key Clauses
Clause 4 - Classification
Clause 5 - Requirements
Clause 7 - Tests
Clause 8 - Marking
Annex A - Method for Determination of Compressive Strength
Annex B - Method for Determination of Thermal Conductivity
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.