XPS X250
Grade · default condition
ASTM C578 · EN 13164 · GB GB/T 10801.2
X250 = x250 / ASTM C578 Type IV
Mainstream building board for roofs, floors and under-slab insulation; best cost/strength balance.
Values for the X250 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 | — |
X250DefaultThis page 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 | — |
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 X250?
XPS X250 is XPS in the X250 grade — mainstream building board for roofs, floors and under-slab insulation; best cost/strength balance. XPS X250 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 X250 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).
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 X250 properties
Typical room-temperature values for XPS X250; 19 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 X250 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 X250 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 X250 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 X250 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 X250 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 X250's machinability is excellent (90/100, better than 95% of polymer grades); weldability poor (20/100); formability poor (25/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with XPS X250
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 X250 — frequently asked
What is XPS X250 used for?
XPS X250 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 X250?
XPS X250 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 X250 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 X250 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 X250?
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 X250 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 X250?
XPS X250 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.