Wood fiber insulation without vapor barrier

[Lerhol86]

Hello!
I have added extra insulation to a log house with 90mm wood fiber insulation. Part of one wall consisted of planks due to a previous opening. I've restructured there to be able to insulate, so here the insulation is 260 mm thick.

I've been advised against using a vapor barrier on the actual log structure, but what should I do with just this area? Should I install a vapor barrier only there, or leave it as it is?

I should add that it is a vacation home heated to 12C when we are not there.

Best regards

 

[Lerhol86]

No one?
If I twist the question a bit, can you insulate as thick as 260 without having a vapor barrier/brake? Not optimal energy-wise, of course, but is there a risk of moisture issues?

 

[sinuslinus]

No one?
If I twist the question a bit, can you insulate as thick as 260 without having a diffusion barrier/brake? Not optimal energy-wise of course but is there a risk of moisture problems?

put ängbroms.

 

[Lerhol86]

Okay, so no problem with covering parts of the wall with ångbroms?

 

[sinuslinus]

The log wall should be more vapor-resistant than just the insulation in the stud wall.

What are the arguments against installing a vapor barrier on the log wall?

Are the walls windproof from the outside?

 

[Lerhol86]

It is windproof from the outside. I also considered putting a brake everywhere, but the advice I received is that if it's difficult to seal the brake completely, it might not matter. Then I received further advice to put a brake only on the fully insulated area. The advice comes from construction engineers, I should mention. But I can't make sense of it; it sounds contradictory to me.

 

[sinuslinus]

Have you insulated the inside or outside?

 

[Lerhol86]

Inside and outside with 45 wood fiber. Initially only intended 90 on the outside, but in order to cover the crosscuts and studs that stabilize the frame, it ended up like this.

 

[Utsliten och utdömd]

I had a carpenter visit a month ago who advocated for a vapor brake if we were to have insulation.

However, we have a layer of facade brick and plaster on our house, so we can only insulate internally.

I don't completely understand the idea of skipping it entirely just because it becomes leaky in some places. The idea is to limit the amount of air that can escape, to prevent warm air from leaking (reducing heating) and to limit moisture (which can damage the frame).
It should be able to breathe in one direction so that moisture can go back into the living area. Not trapping moisture that might get through leaks is the advantage of a brake compared to a barrier. So what is the risk of installing it everywhere, do they mean?
If the idea is to insulate and reduce heating, then the brake should help quite a bit.

I am also interested in this because we might insulate as well.

 

[surris]

You should at least install a vapor barrier in the area with 260mm insulation.
For the rest, you don't need to install a vapor barrier, but it won't hurt to do so if you intend to keep it heated year-round.
The only damage is to your wallet

 

[Lerhol86]

I had a carpenter visit us a month ago who advocated for a vapor retarder if we were to have insulation.

However, we have a layer of facade brick and plaster on our house so we can only insulate internally.

I don't fully understand the idea of skipping it entirely just because it becomes leaky in certain places. The idea is to limit the amount of air that can escape, to avoid losing warm air (reduce heating) and to limit moisture (which can damage the frame).
It should be able to breathe in one direction so that moisture can go back into the living area again. Not trapping moisture that may get through in leaks is the advantage of a retarder compared to a barrier. So what is the risk of installing it everywhere, they mean?
If the idea is to insulate and reduce heating, then the retarder should help quite a bit.

I'm also interested in this since we might insulate as well.

I completely agree with your thoughts. Received the advice in a rush, so there haven't been any lengthy explanations. But if I interpreted one of them correctly, the timber frame would become colder with a vapor retarder=risk factor. The consequence of not having a vapor retarder everywhere might be that the moist air could become more concentrated in certain places? What do I know... I called Hunton for advice, and they also said that I could cover everything without any problem (although they probably have an interest in selling ), but this option is what we're leaning towards right now.

 

[Lerhol86]

You should at least put a vapor barrier on the area with 260mm insulation.
For the remaining area, you don't need to put a vapor barrier, but it doesn't hurt to do so when you intend to keep it heated year-round.
The only harm is to the wallet

Thanks for the advice! Sounds wise even if the wallet takes a hit.