Insulation·glass wool 30mm
glass wool · 30mm
R 0.81
U 1.02 W/m²·K

glass wool, 30 mm — R 0.81

30 mm divided by a conductivity of 0.037 gives an R-value of 0.81. The U-value is 1.02, so a square metre leaks 20.39 W across a 20-degree difference.

Standards it meets

Not up to any of them yet

Material
glass wool
Thickness
30 mm
Thermal conductivity
0.037 W/m·K
Thermal resistance
0.81 m²·K/W
U-value
1.02 W/m²·K
Heat lost per square metre
20.39 W
As concrete
1.3 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 panel6 mm
  • phenolic foam16 mm
  • rigid polyurethane19 mm
  • extruded polystyrene23 mm
  • graphite EPS25 mm
  • white EPS29 mm
  • mineral wool32 mm
  • cellulose34 mm
  • timber105 mm
  • plasterboard146 mm
  • concrete1297 mm

Nearby cells

glass wool 20mm
R 0.54
glass wool 50mm
R 1.35
white EPS 30mm
R 0.83
mineral wool 30mm
R 0.75

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 30mm
R 4.29
phenolic foam 30mm
R 1.5
rigid polyurethane 30mm
R 1.3
extruded polystyrene 30mm
R 1.07
graphite EPS 30mm
R 0.97
white EPS 30mm
R 0.83
glass wool 30mm
R 0.81
mineral wool 30mm
R 0.75
cellulose 30mm
R 0.71
timber 30mm
R 0.23
plasterboard 30mm
R 0.17
concrete 30mm
R 0.02

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 30 mm of glass wool?

0.81 — 30 mm in metres divided by a conductivity of 0.037.

Q. And the U-value?

1.02. That is 0.98 — the resistance plus 0.17 of surface — turned upside down, and a square metre leaks 20.39 W across 20 degrees.

Q. How much concrete would match it?

1.3 metres.

Q. Which standards does it meet?

At 1.02 it does not clear any of them yet.