Insulation·concrete 250mm
concrete · 250mm
R 0.16
U 3.065 W/m²·K

concrete, 250 mm — R 0.16

250 mm divided by a conductivity of 1.6 gives an R-value of 0.16. The U-value is 3.065, so a square metre leaks 61.3 W across a 20-degree difference.

Standards it meets

Not up to any of them yet

Material
concrete
Thickness
250 mm
Thermal conductivity
1.6 W/m·K
Thermal resistance
0.16 m²·K/W
U-value
3.065 W/m²·K
Heat lost per square metre
61.3 W
As concrete
0.25 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 panel1 mm
  • phenolic foam3 mm
  • rigid polyurethane4 mm
  • extruded polystyrene4 mm
  • graphite EPS5 mm
  • white EPS6 mm
  • glass wool6 mm
  • mineral wool6 mm
  • cellulose7 mm
  • timber20 mm
  • plasterboard28 mm

Nearby cells

concrete 200mm
R 0.13
concrete 300mm
R 0.19
plasterboard 250mm
R 1.39

Same material, other thicknesses

concrete 10mm
R 0.01
concrete 20mm
R 0.01
concrete 30mm
R 0.02
concrete 50mm
R 0.03
concrete 70mm
R 0.04
concrete 100mm
R 0.06
concrete 120mm
R 0.08
concrete 150mm
R 0.09
concrete 200mm
R 0.13
concrete 250mm
R 0.16
concrete 300mm
R 0.19
concrete 400mm
R 0.25

Same thickness, other materials

vacuum panel 250mm
R 35.71
phenolic foam 250mm
R 12.5
rigid polyurethane 250mm
R 10.87
extruded polystyrene 250mm
R 8.93
graphite EPS 250mm
R 8.06
white EPS 250mm
R 6.94
glass wool 250mm
R 6.76
mineral wool 250mm
R 6.25
cellulose 250mm
R 5.95
timber 250mm
R 1.92
plasterboard 250mm
R 1.39
concrete 250mm
R 0.16

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 250 mm of concrete?

0.16 — 250 mm in metres divided by a conductivity of 1.6.

Q. And the U-value?

3.065. That is 0.33 — the resistance plus 0.17 of surface — turned upside down, and a square metre leaks 61.3 W across 20 degrees.

Q. How much concrete would match it?

0.25 metres.

Q. Which standards does it meet?

At 3.065 it does not clear any of them yet.