Vapour Permeability to Vapour Resistivity or Mu-value

[Leigh Caller]

Can any members with experience in hygrothermal simulation know how I go about converting the vapour permeability of a material (100 mg/mē/h) to an equivalent vapour resistivity or mu. I am attempting to compare the vapour resistance of a Multi-Pro magnesium silicate board with other products such as plasterboard and Fermacell. However, the magnesium board datasheet only gives the vapour permeability in mg/mē/h.

Any guidance gratefully received as the manufacturer is not much help.

[Ruairi]

Hi

Build desk have a handy explanation of how to convert the various vapour resistance  metrics here:

http://builddesk.co.uk/wp-content/uploads/2013/01/vapourResistances.pdf

Ruairi

[fostertom]

It doesn't cover the conversion from permeability and IMHO is written to confuse. So many units to convert - I don't trust to getting it right, am also looking for a definitive set of conversions.