C578 Type VII FR-B1
Flame-retardant grade
FR-B1 = fire-retardant grade to GB 8624 B1
Specify for Chinese building envelopes where B1-class reaction-to-fire certification is mandatory.
Values for the FR-B1 condition
What is C578 Type VII FR-B1?
C578 Type VII FR-B1 is C578 Type VII in the FR-B1 grade — specify for Chinese building envelopes where B1-class reaction-to-fire certification is mandatory. C578 Type VII FR-B1 has a tensile strength of 0.55 MPa (0.0798 ksi), weaker than 88% of polymer grades. The elastic modulus is 0.02 GPa (0.0029 Msi). C578 Type VII FR-B1 has a density of 0.04 g/cm³ (0.0013 lb/in³), lighter than 91% of polymer grades. Its glass-transition temperature is 100°C (212 °F).
Advantages
- Lightweight — 0.04 g/cm³ (0.0013 lb/in³), better than 91% of polymer grades
- Easy to machine — 85/100, better than 88% of polymer grades
- Low moisture uptake — 0.1%, better than 77% of polymer grades
Limitations
- Poor heat conductor — 0.03 W/m·K (0.0173 BTU/hr·ft·°F), worse than 96% of polymer grades
- Degrades in UV without stabilisers — 15/100, worse than 95% of polymer grades
- Low stiffness — 0.02 GPa (0.0029 Msi), worse than 75% of polymer grades
C578 Type VII FR-B1 properties
Typical room-temperature values for C578 Type VII FR-B1; 4 are specific to this condition. Other listed values are C578 Type VII reference data and may not represent this condition. Bars are the position among polymer grades.
Physical4
C578 Type VII FR-B1 has a density of 0.04 g/cm³ (0.0013 lb/in³), lighter than 91% of polymer grades. Its glass-transition temperature is 100°C (212 °F).
Mechanical8
C578 Type VII FR-B1 has a tensile strength of 0.55 MPa (0.0798 ksi), weaker than 88% of polymer grades. The elastic modulus is 0.02 GPa (0.0029 Msi).
Thermal8
C578 Type VII FR-B1 is rated for continuous service to 75°C (167 °F). It conducts heat at 0.03 W/m·K (0.0173 BTU/hr·ft·°F), worse than 96% of polymer grades. Thermal expansion is 70 µm/m·K (38.9 µin/in·°F).
Electrical1
Chemical & Environmental2
UV resistance is poor.
Sustainability4
Producing a kilogram of C578 Type VII FR-B1 takes about 105 MJ of energy and emits 5 kg of CO₂ — more than 54% of polymer grades. Typical recycled content is 10%.
Manufacturability4
C578 Type VII FR-B1's machinability is excellent (85/100, better than 88% of polymer grades); weldability poor (20/100); formability poor (25/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C578 Type VII FR-B1
Is C578 Type VII easy to machine?
Cut with hot wire, sharp knife or fine-tooth saw; routing and CNC shaping are easy but generate static-clinging dust — use vacuum extraction.
Can C578 Type VII be welded?
Not weldable; boards are joined by shiplap/ship-edge interlock, foam-compatible polyurethane adhesive or mechanical plates.
Can C578 Type VII be formed, bent or molded?
Supplied as extruded board only; no post-forming — thermal shaping above ~80 °C collapses the cells and destroys R-value.
What surface finishes work on C578 Type VII?
Protect from UV and solvents: cover with slab concrete, screed, cement-board render or mat facer; use only water-based or foam-safe adhesives and coatings.
C578 Type VII 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 |
|---|---|---|
| polymeric brominated flame retardantbutadiene-styrene brominated copolymer, replaces legacy HBCD | 0.5 – 2.5 | 1.2 |
| nucleating agent (talc) | 0.3 – 1.5 | 0.8 |
| residual blowing agent (CO2 / HFO-1234ze | 0.5 – 3 | 1.5 |
| polystyrene (general-purpose PS resin)may include post-industrial PS regrind | ≥ 92 (balance) | — |
C578 Type VII FR-B1 — frequently asked
What is C578 Type VII FR-B1 used for?
C578 Type VII FR-B1 is typically used for airport pavement insulation, cold storage floor insulation and heavy traffic deck insulation. In short: heavy-load XPS board; cold-store floor grade; available flame-retardant B1.
What is the tensile strength of C578 Type VII FR-B1?
C578 Type VII FR-B1 has a typical tensile strength of 0.55 MPa (0.0798 ksi) — weaker than 88% of polymer grades.
Is C578 Type VII FR-B1 easy to machine?
Yes — machinability is rated excellent (85/100, better than 88% of polymer grades). Cut with hot wire, sharp knife or fine-tooth saw; routing and CNC shaping are easy but generate static-clinging dust — use vacuum extraction.
Can C578 Type VII FR-B1 be welded?
Not readily — weldability is rated poor (20/100). Not weldable; boards are joined by shiplap/ship-edge interlock, foam-compatible polyurethane adhesive or mechanical plates.
What surface finishes work on C578 Type VII FR-B1?
Protect from UV and solvents: cover with slab concrete, screed, cement-board render or mat facer; use only water-based or foam-safe adhesives and coatings.
Can C578 Type VII FR-B1 be formed, bent or molded?
Supplied as extruded board only; no post-forming — thermal shaping above ~80 °C collapses the cells and destroys R-value.
What is the maximum service temperature of C578 Type VII FR-B1?
C578 Type VII FR-B1 is rated for continuous use to about 75°C (167 °F), and briefly to 85°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- ASTM C578 — Standard Specification for Rigid, Cellular Polystyrene Thermal Insulation — ASTM International (2022)
- ASTM D1621 / D1623 / C203 / C272 / C518 test methods for rigid cellular plastics — ASTM International (2021)
- Extruded polystyrene board technical data (60 psi / high-load grades) — Owens Corning / DuPont / Kingspan (2023)
- 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.