Yes, but if you already have a waterproof layer in the form of a rubber membrane, then you don't need a vapor barrier. But perhaps it doesn't work with prefab?halotex said:
There's no point in the ÅB-foil. From what I understand, it is there to prevent warm and humid air from diffusing into the insulation, especially in winter, and the insulation becoming moist and thus ceasing to insulate. Right?
It sounds like these "Goretex"-like products can be very expensive...?
I have spoken with Tartan and in my opinion, he seems to be a man with many years of carpentry experience and also a theoretical understanding of moisture mechanisms (I am a civil engineer in physics myself, so I think I have some understanding of natural laws at least). Thanks for the help, Tartan!
Anyway, I have now talked to the carpenter and he says that there is actually an air gap behind the plaster that opens into adjacent rooms and therefore removes moisture, and he might have a point there. But, since the plaster is installed, but not the waterproofing layer, I will drill a few holes to puncture the vapor barrier.
By the way, Tartan, are there any cement-based boards that are not as horrifically expensive as, for example, Minerit? I mean, it's about a factor of 10 compared to plaster.
Anyway, I have now talked to the carpenter and he says that there is actually an air gap behind the plaster that opens into adjacent rooms and therefore removes moisture, and he might have a point there. But, since the plaster is installed, but not the waterproofing layer, I will drill a few holes to puncture the vapor barrier.
By the way, Tartan, are there any cement-based boards that are not as horrifically expensive as, for example, Minerit? I mean, it's about a factor of 10 compared to plaster.
phulden, I can inform you that we use plastic film to differentiate between the two moisture values we have. RF outside, which is usually lower than our indoor RF. The reason why it is so important that this inner screen is completely sealed is due to the dew point we have in our construction. By ensuring the plastic film is airtight, we work with the mindset that we allow moisture to be transported via our mechanical ventilation, etc. If we puncture this screen (plastic film), there is an imminent risk of moisture convection occurring. This is a process driven by differences in air pressure. Moisture, as we all know, wants nothing more than to condense to return to its original form, liquid. There have been quite a few theories on this subject, double waterproofing layers in bathroom external walls. But experts have never been able to agree on how we should build in these areas. By building with a diffusion-open membrane, we allow moisture to migrate through the construction in a controlled manner, but we secure the construction from convection. If we delve deeper into this area, I think you should check what vapor transmission resistance your rubber membrane holds. It has long been known that we must reach a resistance of over 2 million s/m x 10/3 for it to be classified as vapor-tight.
The cost of building with gortex-like products. Expensive? You only need this on your bathroom's outer wall.
Let's say you have an outer wall that is 5 m wide, 2.40 m high, making 12 sqm of this and it costs around 25 kr/sqm, so this results in a cost of 300 kr. Is this too expensive for the benefits it produces?
Let's say you have an outer wall that is 5 m wide, 2.40 m high, making 12 sqm of this and it costs around 25 kr/sqm, so this results in a cost of 300 kr. Is this too expensive for the benefits it produces?
You can also take part in the Statens Provnings...... own research report.
http://www.sabo.se/Teknik_Filer/Diffsparrochtatskikt.pdf
Good luck!
http://www.sabo.se/Teknik_Filer/Diffsparrochtatskikt.pdf
Good luck!
sounds like a very expensive solution, when you can use diffusion-open plastic instead?Byggaren said:Draw a plan of a bathroom and study the connection in detail at partitions/exterior walls and in section at floor/ceiling before making far-reaching recommendations about excluding/removing the vapor barrier/plastic sheeting in exterior walls or rendering the existing one non-functional by puncturing it.
The wise approach is instead to build a new inner wall with an air gap against the exterior wall and keep the vapor barrier intact in the exterior wall. This way hygroscopic material is not enclosed between two waterproof layers.
Haloman, I'm sure you know a lot about this, I'm convinced of that. But to me, it sounds somewhat like you are speaking on your own behalf (you call yourself Haloman and advocate for Halotex - sounds like a distributor for Mataki?).
When I then try to break down what you say:
Sorry for my know-it-all tone (my dad says I was born that way and got it from my mom), but I find it difficult to have a sales pitch thrown at me when we're trying to sort out what applies. Now it's almost football time. Go Sweden!
When I then try to break down what you say:
Okay, sure, at least in winter.
I would say it is to prevent diffusion; the dew point is the point where the pressure and temperature are such that gas condenses.
Yep
Yes and no. I don't know what you mean by moisture convection. Convection to me is what is commonly referred to as "warm air rises." I would argue that if you puncture the plastic sheeting, there is an overwhelming risk of moist air diffusion occurring. However, diffusion is not (as many believe) a process driven by pressure differences but rather a purely statistical natural drive to increase entropy. You can have two rooms with the exact same pressure and temperatures but with two different humidity levels and with a membrane that allows vapor transfer. After a while, the two rooms will have the same humidity.
Not that I know, at least. What do you mean? Water wants nothing more than to evaporate if the pressure and temperature are right. Moisture and water have no will of their own; they adhere to the laws of nature.
Can you give me some references? Who are the "experts" you mention?
Perhaps. But that's not what my question was originally about. Here, it was a carpenter who wanted to seal in organic material between two sealed layers, and that's what I was asking about. By puncturing one of the layers, we no longer have that situation. The other layer stops both moisture and hopefully (see below) moisture migration, through both pressure difference and diffusion.
Okay. What is 2 million s/m x 10/3? But if the carpenter is using a standard wet room system, I would hope it withstands both moisture and dampness. You've made a point that I should investigate the product.
Sorry for my know-it-all tone (my dad says I was born that way and got it from my mom), but I find it difficult to have a sales pitch thrown at me when we're trying to sort out what applies. Now it's almost football time. Go Sweden!
Ha, ne is a builder himself who has transitioned to these materials after partly taking part in the research studies that have emerged. But also because I shorten my own building time. If I can build correctly and at the same time build faster, then I don't need to be convinced any more.
I hope you read through this article, which for me is written by an expert in the subject.
http://www.sabo.se/Teknik_Filer/Diffsparrochtatskikt.pdf
And I think it says a lot about your question mark on the matter!
Good luck!
I hope you read through this article, which for me is written by an expert in the subject.
http://www.sabo.se/Teknik_Filer/Diffsparrochtatskikt.pdf
And I think it says a lot about your question mark on the matter!
Good luck!
Now I have read and also talked with Anders Jansson who authored it. The essence of SP's study is that the most important thing is that the waterproofing layer is tight (>1 million s/m). Then the presence or absence of plastic foil actually no longer has any significance. With less tight material, there is a risk that the material between the waterproofing and the PE foil becomes damp, resulting in attacks if it is organic. This has been seen (pictures are in the report). If the PE foil is removed, the rest of the wall construction can potentially be attacked, but there are no results on this yet.Haloman said:
Thus, the most important thing is to choose a waterproofing product that really is tight.
Thanks for the help and hope we've become a bit wiser now!
where can one find the file again?
http://www.sabo.se/Teknik_Filer/Diffsparrochtatskikt.pdf
No longer available and have searched both sp.se and sabo.se without results.
http://www.sabo.se/Teknik_Filer/Diffsparrochtatskikt.pdf
No longer available and have searched both sp.se and sabo.se without results.
I would also like to read that file. I am currently plasting my exterior walls and am pondering back and forth whether to use plastic or not on the bathroom walls (which I plan to tile eventually) that are also exterior walls.
By the way, how is it for laundry rooms, is waterproofing prescribed in these according to the new building regulations?
By the way, how is it for laundry rooms, is waterproofing prescribed in these according to the new building regulations?
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I feel I have to respond to you since you have many serious errors in the text.halotex said:
You write: RF outside, which is usually lower than our RF indoors
Oh really? I have an RF of 96% outside right now and 40% indoors.
You are talking about vapor content, which is always higher indoors due to added moisture. The relative humidity, however, varies. Outside it is high in winter and low in summer, indoors it is the opposite, high RH in summer and low in winter. This is because the low vapor content of the outdoor air in winter is heated significantly and then has a low relative humidity (and vice versa, of course).
By ensuring the plastic sheeting is sealed, we build with the mindset that we allow moisture to be transported via our mechanical ventilation, etc. If we puncture this barrier (plastic sheeting), there is a significant risk of moisture convection occurring.
Now you are confusing things again. The vapor barrier in the exterior wall is used to prevent indoor air from condensing against a cooler material inside the insulated wall. This phenomenon occurs regardless of whether you have negative pressure or not. Negative pressure (due to mechanical exhaust) in a modern house prevents convection in most cases.
To the thread starter: The construction you describe is NOT approved. It has long been known that you should never enclose material (organic) between two waterproof layers. Gypsum, however, doesn't matter much.
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