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Designed for inverted flat, green and blue roofs.


Thermal insulation board designed for inverted flat roofs, offering architects and specifiers thin extruded polystyrene (XPS) insulation with a design lambda of 0.028, and declared lambda 0.027 W/mK for the whole thickness range from 70–205 mm.

It is a high-performance, multipurpose polystyrene for the thermal insulation and frost protection of inverted flat, green and blue roofs. It is manufactured by an extrusion process, which results in a homogeneous, closed cell material structure and smooth surface skin (extrusion skin) which has many favourable material characteristics.

Features and benefits:

  • Excellent thermal insulation capability.
  • Waterproof; negligible moisture uptake.
  • Energy-saving.
  • Cost-efficient solution.
  • Environmentally friendly.
  • Resistant to high loads.
  • Simple installation.
  • High compressive strength.


Designed for inverted flat, green and blue roofs.

General information



Extruded polystyrene (XPS) and fibre cement


600 x 1250 mm (w x l)

Uniclass 2015
Extruded polystyrene (XPS) boards (Pr_25_71_63_29)Primary
Specification data - Extruded polystyrene (XPS) boards
Product Reference

Ravatherm XPS X Ultra 300 SL

Fire performance

Euroclass E (to BS EN 13501-1)

Compressive strength (minimum) at 10% compression

300 kPa (to BS EN 826)

Thermal conductivity (maximum)

0.027 W/mK (to BS EN 13164)


70 mm

2.59 m²K/W thermal resistance.

80 mm

2.96 m²K/W thermal resistance.

105 mm

3.89 m²K/W thermal resistance.

130 mm

4.81 m²K/W thermal resistance.

145 mm

5.37 m²K/W thermal resistance.

175 mm

6.48 m²K/W thermal resistance.

205 mm

7.59 m²K/W thermal resistance.



Standard product features




Excellent thermal insulation capability.




Extruded polystyrene (XPS) and fibre cement.


600 x 1250 mm (w x l).

Technical characteristics:

  • Maximum compressive creep after 50 years (<2% deformation under stress σC, to BS EN 1606): 110 kPa.
  • E-modulus (typical, to BS EN 826): 12–20 MPa.
  • Long-term water absorption by total immersion (to BS EN 12087): <0.7% (after 28 days).
  • Long-term water absorption by diffusion (to BS EN 12088): 50–80 mm: ≤2%; ≥80 mm: ≤1%.
  • Water vapour diffusion resistance factor, μ (to EN ISO 10456): 150.
  • Freeze-thaw, after 300 cycles (to BS EN 12091): ≤1%.
  • Dimensional stability under specified temperature (70°C) and humidity conditions (90% rh) (to BS EN 1604): ≤5%.
  • Deformation under specified compressive load and temperature conditions (to BS EN 1605): ≤5%.
  • Linear thermal expansion coefficient: 0.07 mm/mK.
  • Maximum service temperature: -50/ +75°C.
  • Capillarity: 0.
  • Typical density (to BS EN 1602): 32 kg/m³.
  • Tensile strength (to EN 1607): 300 kPa.

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