vapor barrier

[roggabear]

Hello,
how should one handle the presence or absence of a vapor barrier in the following case:
(see image for numbered references)
The existing exterior wall (1) is additionally insulated with 95 mm mineral wool, but lacks an internal vapor barrier.
A floor has been added to the house and I intend to install a vapor barrier in the ceiling, sloped ceiling, and exterior walls (support beams) (3) on the upper floor.
How should I address this on the part of the intermediate floor marked with (2) in the image? Insulation will be placed there, at least 220 mm. Should I extend the vapor barrier down from the sloped ceiling, through the support beams, and then out towards the eaves up to (4), i.e., over the entire (2) or should I stop the vapor barrier at the junction of the support beams and intermediate floor (5)?
I don't have a vapor barrier in the exterior wall on the ground floor to connect the new vapor barrier to.
Or should I not have a vapor barrier at all, i.e., not in the ceiling, sloped ceiling, exterior wall on the upper floor, since I don't have it on the existing ground floor?

 

[meckis]

Is it a stone house or a wooden house?

 

[roggabear]

Wooden house

 

[meckis]

are the support legs hidden, so you have small kattvindar as well? if not, it's probably easiest to plastic all the way down and past the support legs.

 

[roggabear]

that's correct, the support legs become the walls of the upper floor, i.e., I have kattvindar.

 

[roggabear]

bump
no one has any ideas on how I should proceed with a vapor barrier in my example?

 

[meckis]

it's not entirely easy in your case, because you don't have any vapor barrier at all in the house, it's not fun to try to complete it to 100% since you'd basically have to redo all the spaces to get it in...

but maybe focus primarily on the cold attic? that's usually where the most problems occur. take room by room and put plastic in the ceilings when you renovate. try to seal off against the interior wall as tightly as possible. if you then replace interior walls, you can continue connecting with plastic and cover the walls.

skip the knee wall space for now. it's normally closed, right? otherwise, seal the door leading in there so you don't unnecessarily let in moisture that way. otherwise, you'd have to tear down the wall to cover the entire sloped ceiling with plastic. and that's not so appealing, is it?

 

[John J]

Use wind barrier instead, would never put up a vapor barrier anywhere.

It's enough that you put up a painting or something else and there's a hole, and the whole function collapses.

 

[roggabear]

Pb

It is enough that you put up a picture or something else so there are holes and the whole function fails.

Nja, I will have 45 mm insulation inside the vapor barrier, so it should be fine to hang things on the wall without problems with a damaged vapor barrier.

 

[roggabear]

it's not entirely easy in your case, because you don't have any vapor barrier at all in the house, it's not fun to try to complete to 100% as you would practically have to redo all the spaces to get it there.

but maybe focus primarily on the attic? that's where you usually have the most problems. take it room by room and install plastic in the ceilings when you renovate. try to seal against the interior wall as tightly as possible. if you then change interior walls, you can connect further with plastic and plasticize the walls.

skip the crawl space for now. it's normally closed, right? otherwise, seal the door there so you don't unnecessarily let moisture in that way. otherwise, you'd have to tear down the wall to plasticize the entire sloped ceiling. and that's not so appealing?

The upper floor isn't finished yet, so I'm pretty free to do as I like.

 

[John J]

Pb

Well, I will have 45 mm insulation inside the vapor barrier, so it should be fine to hang things on the wall without issues with a damaged vapor barrier.

Nice!

And what will you put outside the vapor barrier?

 

[meckis]

will be great to mount 45 outside the vapor barrier, then you can run electricity and so on with ease without puncturing anything! then osb+gypsum? or just gypsum? I assume you're also adding 45 insulation?

 

[roggabear]

Nice!

And what will you put outside the vapor barrier?

The wall construction in the gables will be

Panel
Batten/Air gap
Wind protection
45x195 stud / 195 insulation vertical
vapor barrier
45x45 stud / 45 insulation horizontal
OSB
Gypsum

In the sloped roof and at the support beams, it will be the following inside the boarding
45 mm air gap
170 insulation
45x45 stud / 45 insulation horizontal
vapor barrier
45x45 stud / 45 insulation vertical
gypsum (possibly OSB instead)
gypsum

 

[roggabear]

It will be great to add 45 externally to the vapor barrier, then you can easily run electricity, etc., without puncturing anything! Then OSB+gypsum? Or just gypsum? I assume you're also adding 45 insulation?

Yes, I think that will work well, but the question is how I should solve it with the vapor barrier in the "kattvinden", i.e., should I extend it towards the eaves or stop at the support legs?

 

[meckis]

if you intend to use the kattvinden as a cold attic, it would have been easier to have the plastic at the support legs.