Outside insulation when there is a vapor barrier?

[Garald]

As some of you know, I'm at the end (I hope!) of a major renovation.

 

My place now has two kinds of wall insulation - both of them on the inside.

- On the south side and a bit of the west side, I have a thick layer of BioFib Trio (cotton-linen-hemp), with an R>4. Everything should be fine there. There are some thin veils inside het

- On the north side and bits of the west and east sides, due to sui generis advice/orders that did not come from here and may be questionable, there's a combination of a reflective insulator (Actis Hybris) and 5cm of BioFib Trio.

 

People here have discussed plenty how well reflective insulation performs. Let me not do so here - suffice it to say that the north-side rooms are a bit colder (but then they would be: it is the north side). If Actis Hybris performs as its manufacturer claims, then the wall does surpass R=4.

 

Let us just say that I am considering the possibility of insulating the north side from the outside, eventually, in the medium-long run, without touching what has been done already, if I can help it.

 

Now, BioFib has the virtue of being a moisture regulator. Actis hybris, on the other hand, is meant to be impermeable to water vapor.

 

What sort of outside insulation should I aim for, then, so as to avoid condensation issues? Porous? Not porous? Or am I neglecting other, more questions here?