Hello,

I bought a wooden cabin/house in Sweden around 70 sqm (750 sqft) and am now renovating it…
I’ve read a lot of things about vapor barriers and understand I should definitely do this for the walls and ceilings as I’m changing those anyway.
But when it comes to the floor I can’t seem to find the correct info based on my type of building.

My house is built on a pier and beam foundation, so one can look under the house and see the other side… No walls around this area, it’s completely open.

My question here is, should I also have a vapor barrier on my floor (at the warm side of my insulation)??
Or could this cause more problems than it would prevent?

Some more info just to make it easier:
Winter temperature can go as low as -25°C (-13 °F) but that’s more in extreme periods.
Mostly not for a long time.

There’s a constant airflow underneath the house.
The thickness of insulation is mostly 10cm (4 inches) but sometimes 15cm (6 inches).
The bottomside is already partly insulated with 5cm (2 inches) xps boards.

I was thinking to complete these xps boards for the whole building so there are no gaps.