extruded polystyrene, 250 mm — R 8.93

Standards it meets

• passive house 0.15
• Korean central-region wall 0.17
• loose standard 0.30

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 panel63 mm
• phenolic foam179 mm
• rigid polyurethane205 mm
• graphite EPS277 mm
• white EPS321 mm
• glass wool330 mm
• mineral wool357 mm
• cellulose375 mm
• timber1161 mm
• plasterboard1607 mm
• concrete14286 mm

Nearby cells

Same material, other thicknesses

Same thickness, other materials

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.