Insulate exterior wall from the inside - more thoughts

[Overgaard]

If soundproofing is also needed, it's a good idea to consider what needs to be isolated and how high the standards are.

Isocell also has a vapor barrier, I have it in my house

Thanks for the reply. Feel free to check my reply further down with a sketch of the wall

 

[Rabbithole]

Since you have a densely plastered wall, neither the air gap nor the paper should have any function. Normally, you build with an air gap between the facade brick and the insulation.

 

[Overgaard]

Since you have a dense plastered wall, neither the air gap nor the paper should have any function.
Normally, you build with an air gap between the facade brick and insulation.

I was thinking about possible moisture that might seep in from the outside? So you think I can just put wall studs and wood fiber insulation directly against the inside of the outer wall? As long as I have a vapor barrier from the inside to prevent humid air from finding its way through the wall and condensing on/in the cold wall?

I renovated another part of the premises last year, and then I was advised to have an air gap between the wall and insulation, etc. (thus a room within a room so to speak). But that was a plastered brick wall and nothing else.

So hence my thoughts and questions. I don't want to do anything wrong. At the same time, I do want it better insulated. I'm working on the underfloor heating right now. I don't want to heat for the birds but rather get the room warm without a lot of heat leakage.

 

[Rabbithole]

The air gap must be ventilated if it is to serve any purpose. In fact, it should be ventilated between the framework and the facade layer. However, there are many houses that work without an air gap too.

 

[sinuslinus]

If moisture goes through the log wall, you'll likely have other problems than just damp insulation. If you use hygroscopic insulation, it can manage and dry out moisture variations. If you're going to have a ventilated air gap, it should definitely not be in the middle of the wall. Otherwise, you'll be heating the outside for no reason. An airtight layer inside the wall primarily serves as insulation air sealing. Then, you don't know how windproof the outer shell of an older house is, but an unventilated plastered facade, which I assume you have, should be windproof.

 

[Overgaard]

If moisture goes through the timber wall, you will have other problems than just damp insulation. If you use hygroscopic insulation, it can handle and dry out moisture variations.
If you want a ventilated air gap, it absolutely should not be in the middle of the wall. You'll end up heating the outdoors.
An air-tight layer inside the wall is mostly for sealing the insulation. We don't know how airtight the outer shell of an older house is, but an unventilated plastered facade, which I assume you have, should be airtight.

What you say makes a lot of sense. Go ahead with studs directly on the timber/plank wall with wind paper first (mostly for the airtightness for the insulation then). And with hygroscopic insulation

 

[sinuslinus]

Preferably, place studs or battens inside the vapor barrier to prevent all screws from perforating it. In the space, you can run electrical wiring.

 

[Rabbithole]

You can run a layer of horizontal studs, then a vapor barrier, and then vertical studs on top of that. Keep in mind that 2/3 of the insulation should be outside the vapor barrier.