XPS FR-B2
Flame-retardant grade
ASTM C578 · EN 13164 · GB GB/T 10801.2
Economy fire-rated board for floors, under-slab and non-façade uses where only B2 is required.
Values for the FR-B2 condition
Other XPS grades and fills
XPS is listed in 8 conditions; see the grade overview at XPS.
Compare all 8 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
X150 / ASTM C578 Type X | Lightest economy grade for cavity walls, sheathing and non-load-bearing insulation. | 0.26 | 0.3 | 3 | — |
X200 / W200 | Intermediate grade for wall and floor heating layers where 250 kPa is not required. | 0.35 | 0.4 | 3 | — |
X250Default X250 / ASTM C578 Type IV | Mainstream building board for roofs, floors and under-slab insulation; best cost/strength balance. | 0.4 | 0.45 | 3 | — |
flame-retardant board, GB 8624 B1(B) rating | Mandatory grade for most Chinese building façade and roof insulation projects requiring B1 fire performance. | 0.4 | 0.45 | 3 | — |
FR-B2This page flame-retardant board, GB 8624 B2 rating | Economy fire-rated board for floors, under-slab and non-façade uses where only B2 is required. | 0.4 | 0.45 | 3 | — |
X300 / ASTM C578 Type VI | For loaded floors, inverted roofs and cold-store floors with moderate traffic. | 0.45 | 0.5 | 3.5 | — |
X350 / ASTM C578 Type VII | High-strength grade for road/railway frost protection and heavy under-slab loads. | 0.52 | 0.6 | 3.5 | — |
X500 / ASTM C578 Type V | Highest-density XPS for airport aprons, tank bases, deep foundations and other high compressive loads. | 0.7 | 0.8 | 4 | — |
What is XPS FR-B2?
XPS FR-B2 is XPS in the FR-B2 grade — economy fire-rated board for floors, under-slab and non-façade uses where only B2 is required. XPS FR-B2 has a yield strength of 0.4 MPa (0.058 ksi) and a tensile strength of 0.45 MPa (0.0653 ksi) — weaker than 96% of polymer grades. Elongation at break is 3% and the elastic modulus is 0.01 GPa (0.0017 Msi). XPS FR-B2 has a density of 0.03 g/cm³ (0.0012 lb/in³), lighter than 93% of polymer grades. Its glass-transition temperature is 100°C (212 °F). X250 is the default condition FabDigit quotes; FR-B2 is available on request or by drawing note.
Advantages
- Easy to machine — 90/100, better than 95% of polymer grades
- Lightweight — 0.03 g/cm³ (0.0012 lb/in³), better than 93% of polymer grades
Limitations
- Poor heat conductor — 0.03 W/m·K (0.0168 BTU/hr·ft·°F), worse than 98% of polymer grades
- Low strength — 0.4 MPa (0.058 ksi), worse than 96% of polymer grades
- Degrades in UV without stabilisers — 15/100, worse than 95% of polymer grades
- Limited ductility — 3%, worse than 83% of polymer grades
- Low stiffness — 0.01 GPa (0.0017 Msi), worse than 79% of polymer grades
XPS FR-B2 properties
Typical room-temperature values for XPS FR-B2; 18 are specific to this condition. Other listed values are XPS reference data and may not represent this condition. Bars are the position among polymer grades.
Physical4
XPS FR-B2 has a density of 0.03 g/cm³ (0.0012 lb/in³), lighter than 93% of polymer grades. Its glass-transition temperature is 100°C (212 °F).
Mechanical10
XPS FR-B2 has a yield strength of 0.4 MPa (0.058 ksi) and a tensile strength of 0.45 MPa (0.0653 ksi) — weaker than 96% of polymer grades. Elongation at break is 3% and the elastic modulus is 0.01 GPa (0.0017 Msi).
Thermal9
XPS FR-B2 is rated for continuous service to 75°C (167 °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
XPS FR-B2 has an electrical resistivity of 1×10¹⁴ Ω·m.
Chemical & Environmental3
Corrosion resistance is very good (75/100), worse than 66% of polymer grades. UV resistance is poor.
Sustainability3
Producing a kilogram of XPS FR-B2 takes about 100 MJ of energy and emits 4.5 kg of CO₂ — less than 61% of polymer grades. Typical recycled content is 10%.
Manufacturability4
XPS FR-B2's machinability is excellent (90/100, better than 95% 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 XPS FR-B2
Is XPS easy to machine?
Cuts easily with hot wire, knife, fine-tooth saw or CNC router; keep speeds low and vacuum the dust, and avoid overheating that melts/collapses cells.
Can XPS be welded?
Not structurally weldable; joints are made by tongue-and-groove interlock plus water-based or PU foam adhesive and taped seams.
Can XPS be formed, bent or molded?
Produced by continuous extrusion foaming with gas injection then sizing/skinning; boards are rigid and only mildly thermoformable, so shapes are cut rather than formed.
What surface finishes work on XPS?
Solvent-free coatings only; needs skin removal or grooving for plaster/mortar adhesion, and must be covered (render, screed, membrane) because it degrades under UV.
XPS 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 / HCFC-1residual gas in closed cells; determines aged λ and carbon footprint | 1 – 6 | 3 |
| flame retardant (brominated polymeric FRwith Sb2O3 or phosphate synergist in B1 grades | 0.5 – 2.5 | 1.2 |
| talc (nucleating agent) | 0.2 – 1.5 | 0.5 |
| pigment / colourantblue/pink/green brand colours | 0.05 – 0.5 | 0.2 |
| polystyrene (styrene homopolymer)GPPS resin, often with some recycled PS | ≥ 90 (balance) | — |
XPS FR-B2 — frequently asked
What is XPS FR-B2 used for?
XPS FR-B2 is typically used for roof/wall insulation panels, below-grade insulation, floral/craft foam and cold storage panels. In short: stronger, drier than EPS; closed-cell moisture resistance; below-grade insulation standard.
What is the yield strength of XPS FR-B2?
XPS FR-B2 has a typical yield strength of 0.4 MPa (0.058 ksi) and a tensile strength of 0.45 MPa (0.0653 ksi) — weaker than 96% of polymer grades. Strength varies by condition: see the 8 listed tempers.
Is XPS FR-B2 easy to machine?
Yes — machinability is rated excellent (90/100, better than 95% of polymer grades). Cuts easily with hot wire, knife, fine-tooth saw or CNC router; keep speeds low and vacuum the dust, and avoid overheating that melts/collapses cells.
Can XPS FR-B2 be welded?
Not readily — weldability is rated poor (20/100). Not structurally weldable; joints are made by tongue-and-groove interlock plus water-based or PU foam adhesive and taped seams.
What surface finishes work on XPS FR-B2?
Solvent-free coatings only; needs skin removal or grooving for plaster/mortar adhesion, and must be covered (render, screed, membrane) because it degrades under UV.
Can XPS FR-B2 be formed, bent or molded?
Produced by continuous extrusion foaming with gas injection then sizing/skinning; boards are rigid and only mildly thermoformable, so shapes are cut rather than formed.
What is the maximum service temperature of XPS FR-B2?
XPS FR-B2 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.
What is the difference between XPS X250 and XPS X500?
X250 is the default condition — mainstream building board for roofs, floors and under-slab insulation; best cost/strength balance. X500: highest-density XPS for airport aprons, tank bases, deep foundations and other high compressive loads. Yield strength is 0.4 MPa in X250 versus 0.7 MPa in X500.
Sources
- ASTM C578-22 Standard Specification for Rigid, Cellular Polystyrene Thermal Insulation — ASTM International (2022)
- EN 13164:2012+A1:2015 Thermal insulation products for buildings — Factory made XPS products — CEN (2015)
- STYROFOAM Brand XPS Insulation product data — Dow / DuPont Performance Building Solutions (2023)
- FOAMULAR XPS Insulation technical bulletins (Types X, IV, VI, VII, 600/1000) — Owens Corning (2022)
- Inventory of Carbon & Energy (ICE) — insulation materials — University of Bath / Circular Ecology (2019)
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.