Diffusion resistance

The diffusion resistance factor μ (mu) shows the vapor permeability of a material. It indicates how many times it will be more difficult to pass the water vapor through the material then through the air. You can see in the table below that the insulating materials from renewable insulation materials have a small value, therefor are mu-vapor-permeable, and the insulation materials from petrochemical raw materials have a large mu-value and be vapor-tight. Therefore use insulation material from renewable raw materials.


The diffusion resistance factor μ (mu) from several insulation materials: 


Insulation from using renewable raw materials  μ

Flax 1 à 2

Hemp 1 à 10

Paper flakes  1 à 2

Wood fiber  1 à 5

Cork 5 à 30

Sheepswool 4 à 5

Straw 2


Insulation mineral raw materials  μ

Perlite 5

Vermiculite 3

Cellular glass  infinite

Silicat-foam granules  3

Glasswool 1

Rockwool 1 à 5


Insulation from petrochemical raw materials λ

EPS 20-100

XPS 150-300

PUR 50 à 185