C578 Type VI HFO
Grade
HFO = low-GWP (HFO-1234ze) blown board
Choose for LEED/EPD projects and jurisdictions restricting HFC blowing agents; thermal and mechanical values essentially unchanged.
Values for the HFO condition
Other C578 Type VI grades and fills
C578 Type VI is listed in 3 conditions; see the grade overview at C578 Type VI.
Compare all 3 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Grooved / channelled drainage board | Grooved face with bonded filter fabric for foundation walls, plaza decks and green roofs needing drainage. | — | 0.43 | 4 | — |
HFOThis page Low-GWP (HFO-1234ze) blown board | Choose for LEED/EPD projects and jurisdictions restricting HFC blowing agents; thermal and mechanical values essentially unchanged. | — | 0.48 | 4 | — |
Borate / insecticide-treated board | Below-grade and slab-edge use in termite-active regions where untreated foam is restricted by code. | — | 0.48 | 4 | — |
What is C578 Type VI HFO?
C578 Type VI HFO is C578 Type VI in the HFO grade — choose for LEED/EPD projects and jurisdictions restricting HFC blowing agents; thermal and mechanical values essentially unchanged. C578 Type VI HFO has a tensile strength of 0.48 MPa (0.0696 ksi), weaker than 89% of polymer grades. The elastic modulus is 0.02 GPa (0.0026 Msi). C578 Type VI HFO has a density of 0.03 g/cm³ (0.0011 lb/in³), lighter than 94% of polymer grades. Its glass-transition temperature is 100°C (212 °F).
Advantages
- Easy to machine — 92/100, better than 99% of polymer grades
- Lightweight — 0.03 g/cm³ (0.0011 lb/in³), better than 94% of polymer grades
- Low moisture uptake — 0.1%, better than 77% of polymer grades
- Low embodied carbon — 3.4 kg CO₂/kg, better than 76% of polymer grades
Limitations
- Poor heat conductor — 0.03 W/m·K (0.0168 BTU/hr·ft·°F), worse than 98% of polymer grades
- Degrades in UV without stabilisers — 15/100, worse than 95% of polymer grades
- Limited formability — 15/100, worse than 79% of polymer grades
- Low stiffness — 0.02 GPa (0.0026 Msi), worse than 76% of polymer grades
C578 Type VI HFO properties
Typical room-temperature values for C578 Type VI HFO; 15 are specific to this condition. Other listed values are C578 Type VI reference data and may not represent this condition. Bars are the position among polymer grades.
Physical4
C578 Type VI HFO has a density of 0.03 g/cm³ (0.0011 lb/in³), lighter than 94% of polymer grades. Its glass-transition temperature is 100°C (212 °F).
Mechanical8
C578 Type VI HFO has a tensile strength of 0.48 MPa (0.0696 ksi), weaker than 89% of polymer grades. The elastic modulus is 0.02 GPa (0.0026 Msi).
Thermal8
C578 Type VI HFO is rated for continuous service to 74°C (165 °F). It conducts heat at 0.03 W/m·K (0.0168 BTU/hr·ft·°F), worse than 98% of polymer grades. Thermal expansion is 70 µm/m·K (38.9 µin/in·°F).
Electrical2
Chemical & Environmental3
Corrosion resistance is excellent (85/100), better than 65% of polymer grades. UV resistance is poor.
Sustainability3
Producing a kilogram of C578 Type VI HFO takes about 105 MJ of energy and emits 3.4 kg of CO₂ — more than 54% of polymer grades. Typical recycled content is 10%.
Manufacturability3
C578 Type VI HFO's machinability is excellent (92/100, better than 99% of polymer grades); formability poor (15/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C578 Type VI HFO
Is C578 Type VI easy to machine?
Cut with hot wire, sharp knife or fine-tooth blade at low speed; router/CNC works but generates static-clinging dust — vacuum extraction recommended.
Can C578 Type VI be welded?
Not weldable in the metal sense; joints are made with mechanical fasteners, tape or XPS-compatible (solvent-free) foam adhesive.
Can C578 Type VI be formed, bent or molded?
Produced by tandem extrusion with gas injection; boards are rigid and cannot be cold-bent — curved shapes are kerf-cut or hot-wire profiled.
What surface finishes work on C578 Type VI?
Skin can be scarified or grooved for plaster/EIFS adhesion; use only water-based or PU coatings and never solvent-based mastics or hot asphalt above ~80 °C.
C578 Type VI 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 |
|---|---|---|
| blowing agent (CO2 / HFO-1234ze / HFC-13residual gas in cells; sets aged R-value | 2 – 6 | 3.5 |
| flame retardant (polymeric brominated, preplaces legacy HBCD | 0.5 – 1.5 | 0.9 |
| nucleating agent (talc) + pigmentcell-size control and brand colour | 0.2 – 1.5 | 0.6 |
| polystyrene (GPPS/recycled PS)extruded closed-cell matrix | ≥ 92 (balance) | — |
C578 Type VI HFO — frequently asked
What is C578 Type VI HFO used for?
C578 Type VI HFO is typically used for parking deck insulation, plaza deck insulation and roadway insulation. In short: mid-load XPS board; plaza and parking deck grade; HFO low-GWP option.
What is the tensile strength of C578 Type VI HFO?
C578 Type VI HFO has a typical tensile strength of 0.48 MPa (0.0696 ksi) — weaker than 89% of polymer grades. Strength varies by condition: see the 3 listed tempers.
Is C578 Type VI HFO easy to machine?
Yes — machinability is rated excellent (92/100, better than 99% of polymer grades). Cut with hot wire, sharp knife or fine-tooth blade at low speed; router/CNC works but generates static-clinging dust — vacuum extraction recommended.
Can C578 Type VI HFO be welded?
Not weldable in the metal sense; joints are made with mechanical fasteners, tape or XPS-compatible (solvent-free) foam adhesive.
What surface finishes work on C578 Type VI HFO?
Skin can be scarified or grooved for plaster/EIFS adhesion; use only water-based or PU coatings and never solvent-based mastics or hot asphalt above ~80 °C.
Can C578 Type VI HFO be formed, bent or molded?
Produced by tandem extrusion with gas injection; boards are rigid and cannot be cold-bent — curved shapes are kerf-cut or hot-wire profiled.
What is the maximum service temperature of C578 Type VI HFO?
C578 Type VI HFO is rated for continuous use to about 74°C (165 °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 C165 / C203 / C272 / C273 / D2863 (test methods referenced by C578) — ASTM International (2021)
- Extruded polystyrene 40 psi board technical data (Owens Corning FOAMULAR / DuPont Styrofoam class) — producer literature (2024)
- Handbook of Polymeric Foams and Foam Technology — polystyrene foam properties — Hanser (2004)
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.