I have a plastered brick house from 1909 with tretex on the walls. Previous owners have wallpapered and painted, but now the tretex has become damp and started to mold in certain areas, the wallpaper bubbled and peeled off at the bottom. I have now torn down the tretex on one wall and the brick wall is plastered behind. I am considering adding 45 mm insulation to avoid cold walls but it seems to be a jungle out there, should I skip the insulation and just plaster and maybe fill it? Help!!
Building conservationist
· 3 512 posts
I'm curious about the answers you get. I also have damp tretex that needs to be replaced at some point. Additionally, the plaster behind has partially fallen off, so replastering is necessary anyway.
If the plaster behind had been in good condition, I would have just repaired it a bit with lime plaster and painted it with breathable paint (probably lime). But since something more extensive needs to be done with the wall, I'm considering putting up träcementplattor. They are said to be slightly insulating and resistant to mold. Then plaster these, probably with lime plaster, so that it remains breathable. All to avoid trapped moisture. I don't know if it's a good plan, so I hope more suggestions come up in this thread.
If the plaster behind had been in good condition, I would have just repaired it a bit with lime plaster and painted it with breathable paint (probably lime). But since something more extensive needs to be done with the wall, I'm considering putting up träcementplattor. They are said to be slightly insulating and resistant to mold. Then plaster these, probably with lime plaster, so that it remains breathable. All to avoid trapped moisture. I don't know if it's a good plan, so I hope more suggestions come up in this thread.
Last edited:
Since I grew up with tretex and also like it as opposed to many others, I will leave some points. This is not an expert opinion you're getting, but more of some thoughts that can hopefully lead forward and maybe even get others to come up with ideas.
First, we can state that tretex is a very porous wood fiberboard. This means it is strongly absorbent if exposed to moisture. I am therefore doubtful if it is right to have it directly against a brick wall. I get the impression that a brick wall can allow moisture migration. Otherwise, how could the tretex have become damp? The moisture, which apparently doesn't come out, migrates downward due to gravity. Why the moisture can't pass through the board is perhaps something someone with more knowledge in physics can explain. Tretex has the same insulation capability as the equivalent thickness of fiberglass/mineral wool. Could it be that the zero point has ended up completely wrong? When the plaster also comes off behind the board, something is not right.
The cottage owner mentions wood-cement panels. I assume these are what you mean: http://www.traullit.se/ Personally, I think it could be a sensible alternative. But, why not call them and see what they think. They should be more knowledgeable about this. Even if they insulate better than tretex, maybe they allow moisture migration more easily.
Nowadays, you can impregnate facades, plastered and brick, to avoid frost damage according to advertisements. Wouldn't that also mean preventing moisture migration?
Malin, if you're thinking of adding insulation, I don't think it's just about putting up studs and squeezing in the insulation. I guess it should be the same as insulating a basement wall, i.e., with ventilating air space in between. If you're just thinking of plastering, I don't understand why you would use filler on it.
Well, that's all. Let's see now if the cork has popped out and more posts come! Good luck!
First, we can state that tretex is a very porous wood fiberboard. This means it is strongly absorbent if exposed to moisture. I am therefore doubtful if it is right to have it directly against a brick wall. I get the impression that a brick wall can allow moisture migration. Otherwise, how could the tretex have become damp? The moisture, which apparently doesn't come out, migrates downward due to gravity. Why the moisture can't pass through the board is perhaps something someone with more knowledge in physics can explain. Tretex has the same insulation capability as the equivalent thickness of fiberglass/mineral wool. Could it be that the zero point has ended up completely wrong? When the plaster also comes off behind the board, something is not right.
The cottage owner mentions wood-cement panels. I assume these are what you mean: http://www.traullit.se/ Personally, I think it could be a sensible alternative. But, why not call them and see what they think. They should be more knowledgeable about this. Even if they insulate better than tretex, maybe they allow moisture migration more easily.
Nowadays, you can impregnate facades, plastered and brick, to avoid frost damage according to advertisements. Wouldn't that also mean preventing moisture migration?
Malin, if you're thinking of adding insulation, I don't think it's just about putting up studs and squeezing in the insulation. I guess it should be the same as insulating a basement wall, i.e., with ventilating air space in between. If you're just thinking of plastering, I don't understand why you would use filler on it.
Well, that's all. Let's see now if the cork has popped out and more posts come! Good luck!
Building conservationist
· 3 512 posts
Well, people up north in the country usually like tretex. 
There is a difference between timber houses and houses made of clay bricks. There is a difference between deep-frozen winters and Skåne's mild and humid winters.
In the cases I know of, the tretex is always nailed directly onto the bricks. I've seen an old clay house with wallpapered tretex that is dry and fine, and then there's no reason to tear it down.
But if the tretex has started to mold, it seems unwise to replace it with new tretex... Especially if it's a summer house that alternates between being heated and cold. In Skåne, moisture is everywhere at certain times of the year, both outdoors and indoors. Additionally, there may have been leaks into the brick wall, for example, at the gable panel or at the windows (rain rarely comes from above but is pressed sideways against the house). I don't think you can guard against moisture in an old house, so it's best to completely avoid materials that absorb moisture and can mold.
To what extent does the tretex contribute to insulation? That is, how much do you lose by just removing it and not replacing it with other insulation? The total wall area of a Skåne-style house isn't actually that large, considering the low ceiling height and many windows, so insulating the wall with a couple of centimeters might not make much difference?
There is a difference between timber houses and houses made of clay bricks. There is a difference between deep-frozen winters and Skåne's mild and humid winters.
In the cases I know of, the tretex is always nailed directly onto the bricks. I've seen an old clay house with wallpapered tretex that is dry and fine, and then there's no reason to tear it down.
But if the tretex has started to mold, it seems unwise to replace it with new tretex... Especially if it's a summer house that alternates between being heated and cold. In Skåne, moisture is everywhere at certain times of the year, both outdoors and indoors. Additionally, there may have been leaks into the brick wall, for example, at the gable panel or at the windows (rain rarely comes from above but is pressed sideways against the house). I don't think you can guard against moisture in an old house, so it's best to completely avoid materials that absorb moisture and can mold.
To what extent does the tretex contribute to insulation? That is, how much do you lose by just removing it and not replacing it with other insulation? The total wall area of a Skåne-style house isn't actually that large, considering the low ceiling height and many windows, so insulating the wall with a couple of centimeters might not make much difference?
Last edited:
Oh, how fun that I got a response!
It's humid in Skåne all year round. I liked the tretex when it was dry, but now I have no choice!
The plaster behind was in poor condition and would come off just by touching it, so now I've replastered it. My brother and I replastered the wall, but it was the first time we plastered such a large area, so it was difficult to get it even and nice, although we are proud of the result I'm better at puttying, so the finish will probably be nicer, which is the only reason I thought of using putty.
I'm still not much wiser when it comes to potential insulation. I live on Söderslätt in the middle of the windy area and imagine that even a little insulation can make a big difference in the indoor climate, as it can get very cold in the house despite the heating...
It's humid in Skåne all year round. I liked the tretex when it was dry, but now I have no choice!
The plaster behind was in poor condition and would come off just by touching it, so now I've replastered it. My brother and I replastered the wall, but it was the first time we plastered such a large area, so it was difficult to get it even and nice, although we are proud of the result
I'm better at puttying, so the finish will probably be nicer, which is the only reason I thought of using putty.I'm still not much wiser when it comes to potential insulation. I live on Söderslätt in the middle of the windy area and imagine that even a little insulation can make a big difference in the indoor climate, as it can get very cold in the house despite the heating...
Building conservationist
· 3 512 posts
I'm also unsure if insulation is needed in the wall and what the best solution is. But to stop drafts, there are other things more important to do. These need to be done in my house, perhaps some of these are relevant for you too?
1. Seal around windows and doors. 2. Insulate upwards towards the attic. Currently, there's only a wooden floor between the room and the attic, that's where we have the biggest heat loss! 3. Install paper or wind barrier in the gable panels. The house gets cold when the wind blows straight through the attic. 4. Try to adjust the inner doors so they don’t gap out towards the hallway. 5. Get a proper attic hatch.
When all this is done, one can start thinking about the walls. The wind can never blow through a brick wall. However, the cold seeps through.
(no, I don't live in the house during winter, but those who lived here before me did, and back then there were only single-pane windows)
1. Seal around windows and doors. 2. Insulate upwards towards the attic. Currently, there's only a wooden floor between the room and the attic, that's where we have the biggest heat loss! 3. Install paper or wind barrier in the gable panels. The house gets cold when the wind blows straight through the attic. 4. Try to adjust the inner doors so they don’t gap out towards the hallway. 5. Get a proper attic hatch.
When all this is done, one can start thinking about the walls. The wind can never blow through a brick wall. However, the cold seeps through.
(no, I don't live in the house during winter, but those who lived here before me did, and back then there were only single-pane windows)
Thanks for the tips, Sommartorparn, I've already done most of it except for checking if there's wind barrier in the gables, that might be the culprit when it comes to wind!
Building conservationist
· 3 512 posts
In this thread on page 2, you'll see pictures and descriptions of how to insulate such a house without creating mold problems. http://www.byggahus.se/forum/isolering/183409-tillaggsisolera-tegelhus-inifran-2.html#post1426272