Vapor barrier in floor above garage and extension over ground?

[AndreasT]

Hello!

I'm wondering how to manage the vapor barrier in the following two cases.

I am planning an extension where part of the floor will be suspended in the air above the entrance, which rests on pillars. How should the vapor barrier be installed here? Should it be placed on the underside of the insulation or on top of the floor decking?

The same question applies to an extension that will be above the garage, which is built on a regular slab on the ground.

Best regards, Andreas

 

[huggan]

The vapor barrier should always be on the warm side.

However, the vapor barrier should only be there if it is heated year-round. For temporary heating, it is recommended without plastic.

 

[Larsa]

Updating a bit:
I have learned that you shouldn't have a vapor barrier in the floor, only in the walls and ceiling. I looked around a bit and now see that there are many different opinions on this, so I don't dare to give a direct answer.....

 

[AndreasT]

Hello!

If you have waterborne underfloor heating, the installation instructions say to lay it on top of floor chipboard.
The house is heated year-round, but the garage is heated occasionally.