Insulation·glass wool 50mm
glass wool · 50mm
R 1.35
U 0.657 W/m²·K

glass wool, 50 mm — R 1.35

50 mm divided by a conductivity of 0.037 gives an R-value of 1.35. The U-value is 0.657, so a square metre leaks 13.15 W across a 20-degree difference.

Standards it meets

Not up to any of them yet

Material
glass wool
Thickness
50 mm
Thermal conductivity
0.037 W/m·K
Thermal resistance
1.35 m²·K/W
U-value
0.657 W/m²·K
Heat lost per square metre
13.15 W
As concrete
2.16 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 panel9 mm
  • phenolic foam27 mm
  • rigid polyurethane31 mm
  • extruded polystyrene38 mm
  • graphite EPS42 mm
  • white EPS49 mm
  • mineral wool54 mm
  • cellulose57 mm
  • timber176 mm
  • plasterboard243 mm
  • concrete2162 mm

Nearby cells

glass wool 30mm
R 0.81
glass wool 70mm
R 1.89
white EPS 50mm
R 1.39
mineral wool 50mm
R 1.25

Same material, other thicknesses

glass wool 10mm
R 0.27
glass wool 20mm
R 0.54
glass wool 30mm
R 0.81
glass wool 50mm
R 1.35
glass wool 70mm
R 1.89
glass wool 100mm
R 2.7
glass wool 120mm
R 3.24
glass wool 150mm
R 4.05
glass wool 200mm
R 5.41
glass wool 250mm
R 6.76
glass wool 300mm
R 8.11
glass wool 400mm
R 10.81

Same thickness, other materials

vacuum panel 50mm
R 7.14
phenolic foam 50mm
R 2.5
rigid polyurethane 50mm
R 2.17
extruded polystyrene 50mm
R 1.79
graphite EPS 50mm
R 1.61
white EPS 50mm
R 1.39
glass wool 50mm
R 1.35
mineral wool 50mm
R 1.25
cellulose 50mm
R 1.19
timber 50mm
R 0.38
plasterboard 50mm
R 0.28
concrete 50mm
R 0.03

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 50 mm of glass wool?

1.35 — 50 mm in metres divided by a conductivity of 0.037.

Q. And the U-value?

0.657. That is 1.52 — the resistance plus 0.17 of surface — turned upside down, and a square metre leaks 13.15 W across 20 degrees.

Q. How much concrete would match it?

2.16 metres.

Q. Which standards does it meet?

At 0.657 it does not clear any of them yet.