EPS · grade · default condition
EPS-20
Properties of the EPS-20 condition, compared with the other EPS grades.
The default balance of insulation value, strength and cost for EIFS boards and industrial packaging.
What is EPS-20?
EPS-20 is EPS in the EPS-20 grade — the default balance of insulation value, strength and cost for EIFS boards and industrial packaging. EPS-20 has a tensile strength of 0.25 MPa (0.0363 ksi), weaker than 95% of polymer grades. The elastic modulus is 0.01 GPa (7.25×10⁻⁴ Msi). EPS-20 has a density of 0.02 g/cm³ (7.23×10⁻⁴ lb/in³), lighter than 98% of polymer grades. Its glass-transition temperature is 100°C (212 °F).
Advantages
- Lightweight — 0.02 g/cm³ (7.23×10⁻⁴ lb/in³), better than 98% of polymer grades
- Easy to machine — 90/100, better than 95% of polymer grades
- Low embodied carbon — 3.4 kg CO₂/kg, better than 76% of polymer grades
Limitations
- Degrades in UV without stabilisers — 15/100, worse than 95% of polymer grades
- Poor heat conductor — 0.04 W/m·K (0.0208 BTU/hr·ft·°F), worse than 92% of polymer grades
- Absorbs moisture — dry before molding — 1.5%, worse than 92% of polymer grades
- Low stiffness — 0.01 GPa (7.25×10⁻⁴ Msi), worse than 89% of polymer grades
EPS-20 properties
Typical room-temperature values for EPS-20 — 8 properties are specific to this condition; the rest are grade-level values shared by every EPS grade. Each bar shows where the value sits among the polymer grades in FabDigit's library — further right is higher.
Physical4
EPS-20 has a density of 0.02 g/cm³ (7.23×10⁻⁴ lb/in³), lighter than 98% of polymer grades. Its glass-transition temperature is 100°C (212 °F).
Mechanical7
EPS-20 has a tensile strength of 0.25 MPa (0.0363 ksi), weaker than 95% of polymer grades. The elastic modulus is 0.01 GPa (7.25×10⁻⁴ Msi).
Thermal8
EPS-20 is rated for continuous service to 75°C (167 °F). It conducts heat at 0.04 W/m·K (0.0208 BTU/hr·ft·°F), worse than 92% of polymer grades. Thermal expansion is 65 µm/m·K (36.1 µin/in·°F).
Electrical4
EPS-20 has an electrical resistivity of 1×10¹⁴ Ω·m.
Chemical & Environmental3
Corrosion resistance is very good (80/100), worse than 55% of polymer grades. UV resistance is poor.
Sustainability4
Producing a kilogram of EPS-20 takes about 105 MJ of energy and emits 3.4 kg of CO₂ — more than 54% of polymer grades. Typical recycled content is 5%.
Manufacturability5
EPS-20's machinability is excellent (90/100, better than 95% of polymer grades); weldability fair (45/100); formability very good (70/100).
Common Calculations4
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other EPS grades and fills
EPS is also supplied in 8 other conditions. The full side-by-side table is on the EPS overview.
- EPS-20DefaultThe default balance of insulation value, strength and cost for EIFS boards and industrial packaging.0.25 MPa tensile
- EPS-40Highest common EPS density for geofoam fill, load-bearing floors and heavy-duty packaging.0.47 MPa tensile
- EPS-30Choose for under-slab, roof deck and geofoam-light duty where compressive load matters.0.36 MPa tensile
- EPS-15Entry-level wall insulation and protective packaging where compressive load is light.0.18 MPa tensile
- EPS-10Cheapest cushioning/void-fill foam where load-bearing and insulation demands are minimal.0.12 MPa tensile
Working with EPS-20
Is EPS easy to machine?
Hot-wire cutting or CNC hot-wire/router with sharp tools and vacuum extraction; avoid friction heat and use light passes to prevent bead pull-out.
Can EPS be welded?
Not fusion-weldable in the plastics-welding sense — blocks are joined by steam fusion during molding, or bonded with water-based/hot-melt adhesives (never solvent adhesives).
Can EPS be formed, bent or molded?
Pre-expand beads with steam, age 6–24 h, then block or shape mold at 0.6–1.2 bar steam and 100–120 °C; allow post-mold drying/aging to stabilize dimensions (0.3–0.8 % shrinkage).
What surface finishes work on EPS?
Coat with cement or acrylic skim coats, water-based paints or laminate facings; solvent paints, PU foam and hot bitumen (>90 °C) will attack the surface, and UV exposure demands prompt covering.
EPS chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| pentane (n-/iso-pentane blowing agent)in raw bead; <0.5 % residual in aged product | 3 – 7 | 5 |
| flame retardant (polymeric brominated, PFR grades only; HBCD phased out | 0.4 – 1.2 | 0.8 |
| nucleating agent / wax, coating (zinc stcell-size and mold-release additives | 0.1 – 1 | 0.4 |
| graphite / carbon IR absorbergrey GEPS variants only | 0.5 – 4 | 2 |
| polystyrene (styrene homopolymer)Mw ≈ 180,000–260,000 | ≥ 90 (balance) | — |
EPS-20 — frequently asked
What is EPS-20 used for?
EPS-20 is typically used for building insulation board, protective packaging, disposable coolers, void fill and lightweight concrete fill. In short: lowest-cost rigid insulation foam; lightest styrenic foam; best cost per R-value.
What is the tensile strength of EPS-20?
EPS-20 has a typical tensile strength of 0.25 MPa (0.0363 ksi) — weaker than 95% of polymer grades. Strength varies by condition: see the 9 listed tempers.
Is EPS-20 easy to machine?
Yes — machinability is rated excellent (90/100, better than 95% of polymer grades). Hot-wire cutting or CNC hot-wire/router with sharp tools and vacuum extraction; avoid friction heat and use light passes to prevent bead pull-out.
Can EPS-20 be welded?
With care — weldability is rated fair (45/100). Not fusion-weldable in the plastics-welding sense — blocks are joined by steam fusion during molding, or bonded with water-based/hot-melt adhesives (never solvent adhesives).
What surface finishes work on EPS-20?
Coat with cement or acrylic skim coats, water-based paints or laminate facings; solvent paints, PU foam and hot bitumen (>90 °C) will attack the surface, and UV exposure demands prompt covering.
Can EPS-20 be formed, bent or molded?
Pre-expand beads with steam, age 6–24 h, then block or shape mold at 0.6–1.2 bar steam and 100–120 °C; allow post-mold drying/aging to stabilize dimensions (0.3–0.8 % shrinkage).
What is the maximum service temperature of EPS-20?
EPS-20 is rated for continuous use to about 75°C (167 °F), and briefly to 90°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- ASTM C578 — Rigid, Cellular Polystyrene Thermal Insulation — ASTM International (2022)
- EN 13163 — Thermal insulation products, factory made EPS — CEN (2016)
- Styropor / Neopor EPS technical information — BASF (2021)
- Engineered Materials Handbook Vol.2: Engineering Plastics — ASM International (1988)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.