I am renovating an old house with a timber frame. The timber is about 8 cm thick and the façade is directly on the outside. The roof also has no insulation. What is the best way to insulate and should one have a vapor barrier on the inside? Our current idea is to insulate 45mm on the inside without a vapor barrier, since electrical conduits will need to be installed, and to use a wind barrier, air gap, and then new façade on the outside. Give me all possible tips regarding this and what works.
If there is a need to change the facade and add some insulation, it sounds like a good approach. Construction proposals can be found at Isolina, if you are using linisolering or similar materials. Insulating attic flooring may also be appropriate to review.
The question of vapor barriers in old houses has been raised in countless threads, most recently here. If it is a summer house and unheated during the year, there is, for example, a discussion here.
The question of vapor barriers in old houses has been raised in countless threads, most recently here. If it is a summer house and unheated during the year, there is, for example, a discussion here.
Just like @Microkatten writes: there are many threads about diffspärr or not. There are many arguments for and against. I thought long and hard when we started renovating our house (built in 1937) about whether I should install a diffspärr or not. I ended up skipping the diffspärr; we'll see if this was wise or not. So far, the house seems to be doing well. The decisive reason why I skipped the barrier was: an old house that never had it before, so I want to keep it that way.
It's a shame there isn't a crystal clear answer to this question. Everything depends on the house, and all houses vary and have their own conditions...
It's a shame there isn't a crystal clear answer to this question. Everything depends on the house, and all houses vary and have their own conditions...
If you are not insulating with at least one decimeter of mineral wool, no vapor barrier is needed. And, as mentioned, if the house is kept cold for large parts of the year, it should not be too airtight either.
However, it can be good to have some form of vapor retarder on the inside if sufficient vapor resistance is not achieved in another way.
However, it can be good to have some form of vapor retarder on the inside if sufficient vapor resistance is not achieved in another way.
Know-It-All
· Västra Götaland
· 12 292 posts
If you plan to insulate more thickly on the outside in the future, it might be wise to use a diffusion barrier/brake. Otherwise, if they're just going to add 45mm, it's not needed.
Member
· Västernorrland
· 12 020 posts
But this particular construction method is probably among the worst, so the question is whether 45mm is enough to achieve anything? Log house is actually the wrong term as well since they're probably made of thick planks only? Usually tongue and groove.
A real log house with either horizontal or vertical logs still has timber that's about 15-20cm, and then a lighter additional insulation can work well.
A real log house with either horizontal or vertical logs still has timber that's about 15-20cm, and then a lighter additional insulation can work well.
They are correct, they are built from rough planks and not real timber.
Since I will be adding more insulation in the roof, it might be enough to have a vapor barrier there and skip it in the rest. I'll keep looking and see what I decide, thanks for all the tips.
Since I will be adding more insulation in the roof, it might be enough to have a vapor barrier there and skip it in the rest. I'll keep looking and see what I decide, thanks for all the tips.
Know-It-All
· Västra Götaland
· 12 292 posts
If you're redoing all the surfaces and it's meant as a permanent residence, you might as well put it everywhere. But at the same time, it's not needed on such thin walls.
Member
· Västernorrland
· 12 020 posts
How big is it? Are the rooms very small? Where is it located? Is it for year-round living? The best thing when you have such houses is often to invest in proper insulation and view the plank wall as a very thick inner or outer wall. Either you insulate on the outside or the inside and lose a lot of floor space. It all depends on how it looks. Then I wouldn't think old-fashioned for such a house, go for modern insulation and fabric and possibly modern vapor barriers. The fact that there is a fairly thick plank wall in the middle doesn't matter and also doesn't make the house something that requires special thinking either. If it's full-thickness timmer and you go with "natural" insulation, then you can start thinking about such things.
It was probably too early in the morning when I read the OP's question; I understood it as a house with 8-inch timber instead of 8 cm! 
This thread (there are more about old plank walls, search the forum) might be applicable, where I agree with @justusandersson and others.
This thread (there are more about old plank walls, search the forum) might be applicable, where I agree with @justusandersson and others.