C578 Type XIII FANFOLD
Grade
FANFOLD = thin fanfold sheathing / underlayment
Thin accordion-folded XPS used as siding underlayment and re-side smoothing layer.
Values for the FANFOLD condition
Other C578 Type XIII grades and fills
C578 Type XIII is listed in 4 conditions; see the grade overview at C578 Type XIII.
Compare all 4 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
High recycled-content board | Uses reclaimed polystyrene for LEED/EPD credit; colour and skin uniformity vary. | — | 0.27 | 2.5 | — |
Low-GWP HFO / CO₂-blown formulation | Current-generation blowing agent for green-building and EPD-driven projects; slightly higher aged λ than legacy HFC boards. | — | 0.3 | 3 | — |
Polymeric flame retardant | Standard for REACH/RoHS-sensitive and Chinese B1-grade markets replacing hexabromocyclododecane. | — | 0.3 | 3 | — |
FANFOLDThis page Thin fanfold sheathing / underlayment | Thin accordion-folded XPS used as siding underlayment and re-side smoothing layer. | — | 0.33 | 3 | — |
What is C578 Type XIII FANFOLD?
C578 Type XIII FANFOLD is C578 Type XIII in the FANFOLD grade — thin accordion-folded XPS used as siding underlayment and re-side smoothing layer. C578 Type XIII FANFOLD has a tensile strength of 0.33 MPa (0.0479 ksi), weaker than 93% of polymer grades. The elastic modulus is 0.01 GPa (8.7×10⁻⁴ Msi). C578 Type XIII FANFOLD has a density of 0.02 g/cm³ (7.95×10⁻⁴ lb/in³), lighter than 97% of polymer grades. Its glass-transition temperature is 100°C (212 °F).
Advantages
- Easy to machine — 96/100, better than 100% of polymer grades
- Lightweight — 0.02 g/cm³ (7.95×10⁻⁴ lb/in³), better than 97% of polymer grades
- Low moisture uptake — 0.1%, better than 77% of polymer grades
Limitations
- Degrades in UV without stabilisers — 12/100, worse than 99% of polymer grades
- Poor heat conductor — 0.03 W/m·K (0.0168 BTU/hr·ft·°F), worse than 98% of polymer grades
- Low stiffness — 0.01 GPa (8.7×10⁻⁴ Msi), worse than 86% of polymer grades
C578 Type XIII FANFOLD properties
Typical room-temperature values for C578 Type XIII FANFOLD; 17 are specific to this condition. Other listed values are C578 Type XIII reference data and may not represent this condition. Bars are the position among polymer grades.
Physical4
C578 Type XIII FANFOLD has a density of 0.02 g/cm³ (7.95×10⁻⁴ lb/in³), lighter than 97% of polymer grades. Its glass-transition temperature is 100°C (212 °F).
Mechanical7
C578 Type XIII FANFOLD has a tensile strength of 0.33 MPa (0.0479 ksi), weaker than 93% of polymer grades. The elastic modulus is 0.01 GPa (8.7×10⁻⁴ Msi).
Thermal8
C578 Type XIII FANFOLD 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).
Electrical3
Chemical & Environmental2
UV resistance is not recommended.
Sustainability4
Producing a kilogram of C578 Type XIII FANFOLD takes about 100 MJ of energy and emits 4.5 kg of CO₂ — less than 61% of polymer grades. Typical recycled content is 10%.
Manufacturability2
C578 Type XIII FANFOLD's machinability is excellent (96/100, better than 100% of polymer grades); formability fair (45/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C578 Type XIII FANFOLD
Is C578 Type XIII easy to machine?
Cut with a utility knife, fine-tooth handsaw or hot-wire table; hot-wire gives clean edges but must be fume-extracted, and routing generates static-clinging dust.
Can C578 Type XIII be welded?
Not weldable; join by mechanical fasteners with large plates, tape, or XPS-compatible foam adhesive.
Can C578 Type XIII be formed, bent or molded?
Supplied as extruded board only — no field thermoforming; thin fanfold sheets can be scored and folded, thicker boards must be kerf-cut for curves.
What surface finishes work on C578 Type XIII?
Must be covered: render/EIFS mesh coat, cladding or a code-approved 15-minute thermal barrier indoors; use only water-based or solvent-free coatings and never hot bitumen directly on the foam.
C578 Type XIII 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 (HFO-1234ze / CO2 / HFC leresidual cell gas; determines aged R-value | 1.5 – 6 | 3 |
| flame retardant (polymeric brominated, f | 0.5 – 2 | 1 |
| nucleating agent (talc) + pigment | 0.1 – 1 | 0.5 |
| polystyrene (general-purpose PS)may include reclaimed PS | ≥ 92 (balance) | — |
C578 Type XIII FANFOLD — frequently asked
What is C578 Type XIII FANFOLD used for?
C578 Type XIII FANFOLD is typically used for wall sheathing insulation, roof insulation and foundation insulation. In short: mid-density C578 board; between Type IV and VI; low-conductivity building board.
What is the tensile strength of C578 Type XIII FANFOLD?
C578 Type XIII FANFOLD has a typical tensile strength of 0.33 MPa (0.0479 ksi) — weaker than 93% of polymer grades. Strength varies by condition: see the 4 listed tempers.
Is C578 Type XIII FANFOLD easy to machine?
Yes — machinability is rated excellent (96/100, better than 100% of polymer grades). Cut with a utility knife, fine-tooth handsaw or hot-wire table; hot-wire gives clean edges but must be fume-extracted, and routing generates static-clinging dust.
Can C578 Type XIII FANFOLD be welded?
Not weldable; join by mechanical fasteners with large plates, tape, or XPS-compatible foam adhesive.
What surface finishes work on C578 Type XIII FANFOLD?
Must be covered: render/EIFS mesh coat, cladding or a code-approved 15-minute thermal barrier indoors; use only water-based or solvent-free coatings and never hot bitumen directly on the foam.
Can C578 Type XIII FANFOLD be formed, bent or molded?
Supplied as extruded board only — no field thermoforming; thin fanfold sheets can be scored and folded, thicker boards must be kerf-cut for curves.
What is the maximum service temperature of C578 Type XIII FANFOLD?
C578 Type XIII FANFOLD 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 C518 / C203 / C272 / C1621 test methods for cellular plastic insulation — ASTM International (2021)
- FOAMULAR XPS insulation product data — Owens Corning (2023)
- STYROFOAM Brand XPS Insulation technical data — DuPont Performance Building Solutions (2023)
- GreenGuard XPS board technical literature — Kingspan Insulation (2022)
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.