Insulation·extruded polystyrene 100mm
extruded polystyrene · 100mm
R 3.57
U 0.267 W/m²·K

extruded polystyrene, 100 mm — R 3.57

100 mm divided by a conductivity of 0.028 gives an R-value of 3.57. The U-value is 0.267, so a square metre leaks 5.35 W across a 20-degree difference.

Standards it meets

  • loose standard 0.30
Material
extruded polystyrene
Thickness
100 mm
Thermal conductivity
0.028 W/m·K
Thermal resistance
3.57 m²·K/W
U-value
0.267 W/m²·K
Heat lost per square metre
5.35 W
As concrete
5.71 m

Thickness for the same performance

This is the number that shows what insulation is worth. Matching 100 mm of XPS with concrete alone would take 5.7 metres of it. No one builds a wall like that — which is why a concrete building only gets warm once a thin layer of insulation is added.

  • vacuum panel25 mm
  • phenolic foam71 mm
  • rigid polyurethane82 mm
  • graphite EPS111 mm
  • white EPS129 mm
  • glass wool132 mm
  • mineral wool143 mm
  • cellulose150 mm
  • timber464 mm
  • plasterboard643 mm
  • concrete5714 mm

Nearby cells

extruded polystyrene 70mm
R 2.5
extruded polystyrene 120mm
R 4.29
rigid polyurethane 100mm
R 4.35
graphite EPS 100mm
R 3.23

Same material, other thicknesses

extruded polystyrene 10mm
R 0.36
extruded polystyrene 20mm
R 0.71
extruded polystyrene 30mm
R 1.07
extruded polystyrene 50mm
R 1.79
extruded polystyrene 70mm
R 2.5
extruded polystyrene 100mm
R 3.57
extruded polystyrene 120mm
R 4.29
extruded polystyrene 150mm
R 5.36
extruded polystyrene 200mm
R 7.14
extruded polystyrene 250mm
R 8.93
extruded polystyrene 300mm
R 10.71
extruded polystyrene 400mm
R 14.29

Same thickness, other materials

vacuum panel 100mm
R 14.29
phenolic foam 100mm
R 5
rigid polyurethane 100mm
R 4.35
extruded polystyrene 100mm
R 3.57
graphite EPS 100mm
R 3.23
white EPS 100mm
R 2.78
glass wool 100mm
R 2.7
mineral wool 100mm
R 2.5
cellulose 100mm
R 2.38
timber 100mm
R 0.77
plasterboard 100mm
R 0.56
concrete 100mm
R 0.06

How to read this

  • Thermal resistance is the thickness in metres divided by the conductivity. Bigger is better.
  • The U-value adds 0.17 of surface resistance and then flips the total. Smaller is better.
  • Resistances add across layers, so a whole wall is the sum of its parts.
  • Conductivity varies by product; the values here are typical for the material.

Frequently asked questions

Q. What is the R-value of 100 mm of extruded polystyrene?

3.57 — 100 mm in metres divided by a conductivity of 0.028.

Q. And the U-value?

0.267. That is 3.74 — the resistance plus 0.17 of surface — turned upside down, and a square metre leaks 5.35 W across 20 degrees.

Q. How much concrete would match it?

5.71 metres.

Q. Which standards does it meet?

At 0.267 it clears 1 of them.