Member
· Västernorrland
· 12 034 posts
There is a difference between various conditions. The climate you get in a shower space should be ventilated out with a fan. (preferably) You cannot expect it to disappear by itself through the walls, as that would create problems. Likewise, you shouldn't think that you can prevent that air from going through walls and ceilings. In an old house with wood and eco-thinking everywhere, you typically skip any form of plastic, but then you need to ensure that you have fans that are moisture-controlled and ventilate until it's okay.Peter_K said:
Renovating the kitchen and framing up 45 for electricity and insulating with flax insulation and internal paper in a wooden house from 1909. Initially, we thought about getting a quote for the job, but it was a bit too complicated with how I wanted it, so we are just taking electrical/plumbing by the hour and doing the rest ourselves. To the point, the guy (who was some kind of construction engineer and seemed serious) from the construction company who came to look at the whole thing, I discussed this with him, and - believe it or not - he was completely on board that in old houses it’s best to do as we did, but he said it often becomes more expensive to do so (they didn’t dare to give a fixed price for the whole job). What he said was that he thought ordinary rooms in old houses would best be done in this way. He believed kitchen has somewhat higher moisture load, but it was still better to go for this, but put paper and seal so there’s nowhere it "blows". However, for bathrooms, he said he always recommended putting plastic, as you seal all materials and there’s a very high moisture load.
Back to the topic. It seems that if you build with materials that can breathe and don’t insulate to "passive level," it might be preferable to build without the plastic, it’s really a very "robust" construction. The downside of plastic is that if something goes wrong you get moisture damage. But as someone wrote, if you insulate a lot and use fiberglass, you will get moisture problems if it condenses in the wall - then you need plastic. And if the plastic is punctured or you don’t manage to install it properly, you get moisture problems. It feels like the plastic is a "risk construction," or if you will, a construction that is very sensitive. If it works well, then of course it is superior to have thick cheap insulation and a house where you can have overpressure without a problem, but the moment it doesn’t work as intended, it’s just bad.
Insulating with materials like flax or eco-fiber is great, but it costs much more. Perhaps almost a factor of 10? I understand that big companies opt for fiberglass, plastic - and previously single-step facade sealing. Every penny saved goes directly to their profit. Moisture problems likely arise first when deficiencies in the plastic lead to leaks that over time cause sick houses.
In a way, I believe that paying a few thousand more per year in heating and drying out the house to avoid moisture problems is more beneficial than superinsulating. But that almost requires geothermal heating and that we don't get escalating electricity prices.
If heating becomes sufficiently expensive, it might justify building a house with perhaps a 40-50 year lifespan, which then due to the inability to maintain without moisture problems (impossible to renovate while maintaining tightness and after 30 years you want to renovate/extend. And over time even the tight age-resistant plastic is punctured).
And speaking of moisture, I think the easily manageable modern paints we have on wooden facades have a similar issue. First, you prime the wood with oil paint, then a relatively tight layer on top. When the tight layer expires, you might paint anew once. But next time you ought to strip it to bare wood and oil it again. If you instead use linseed oil paint, the maintenance interval is tighter, but in return, you skip the task of scraping off all the old paint. But for the first homeowner of the house, who has it for 25 years maybe, the modern paint is definitely cheaper.
Circular thinking and long-term planning are not easy. Should one see homeownership as a lifelong (or multi-generational) project? Or do as many commercial companies aim to do today: tear down after 30 years and build anew. Unfortunately, I believe the latter is becoming more common. There's no profit in renovating something built with these methods. The sad part is when old houses built to last for several hundred years are demolished and replaced with something that only lasts 30.
Back to the topic. It seems that if you build with materials that can breathe and don’t insulate to "passive level," it might be preferable to build without the plastic, it’s really a very "robust" construction. The downside of plastic is that if something goes wrong you get moisture damage. But as someone wrote, if you insulate a lot and use fiberglass, you will get moisture problems if it condenses in the wall - then you need plastic. And if the plastic is punctured or you don’t manage to install it properly, you get moisture problems. It feels like the plastic is a "risk construction," or if you will, a construction that is very sensitive. If it works well, then of course it is superior to have thick cheap insulation and a house where you can have overpressure without a problem, but the moment it doesn’t work as intended, it’s just bad.
Insulating with materials like flax or eco-fiber is great, but it costs much more. Perhaps almost a factor of 10? I understand that big companies opt for fiberglass, plastic - and previously single-step facade sealing. Every penny saved goes directly to their profit. Moisture problems likely arise first when deficiencies in the plastic lead to leaks that over time cause sick houses.
In a way, I believe that paying a few thousand more per year in heating and drying out the house to avoid moisture problems is more beneficial than superinsulating. But that almost requires geothermal heating and that we don't get escalating electricity prices.
If heating becomes sufficiently expensive, it might justify building a house with perhaps a 40-50 year lifespan, which then due to the inability to maintain without moisture problems (impossible to renovate while maintaining tightness and after 30 years you want to renovate/extend. And over time even the tight age-resistant plastic is punctured).
And speaking of moisture, I think the easily manageable modern paints we have on wooden facades have a similar issue. First, you prime the wood with oil paint, then a relatively tight layer on top. When the tight layer expires, you might paint anew once. But next time you ought to strip it to bare wood and oil it again. If you instead use linseed oil paint, the maintenance interval is tighter, but in return, you skip the task of scraping off all the old paint. But for the first homeowner of the house, who has it for 25 years maybe, the modern paint is definitely cheaper.
Circular thinking and long-term planning are not easy. Should one see homeownership as a lifelong (or multi-generational) project? Or do as many commercial companies aim to do today: tear down after 30 years and build anew. Unfortunately, I believe the latter is becoming more common. There's no profit in renovating something built with these methods. The sad part is when old houses built to last for several hundred years are demolished and replaced with something that only lasts 30.
Here is an example of a thesis on construction without vapor barriersRibons said:
http://du.diva-portal.org/smash/get/diva2:732034/FULLTEXT01.pdf
From the conclusion:
9 Conclusion
Based on the results and analyses made in the report, the following conclusions have been drawn:
The wall construction evaluated in the study without vapor barrier and with a single-stage sealed
facade cannot be considered a moisture-safe construction.
The result shows a high relative humidity in the outer layer of the wall construction,
We have enough ventilation. With a 160 pipe almost straight up to the roof fan, it's no problem to ventilate the moisture away. I was more thinking about the walls getting a vapor barrier or waterproof membrane, and that maybe one should have that on the ceiling as well.Stefan1972 said:
Member
· Västernorrland
· 12 034 posts
I wouldn't have it if you have natural materials there, meaning no mineral wool at all. Assuming you/you shower normally and the room dries in between, even what makes it through the ceiling will dry out.Peter_K said:
S
sinuslinus
Träskalle
· Östergötlands län
· 6 027 posts
sinuslinus
Träskalle
- Östergötlands län
- 6,027 posts
Put a moisture-buffering material in the ceiling, like cement-based wood wool. Träullit has developed some nice ceiling products.Peter_K said:
There are different types of vapor brakes as well. They are also used with insulation made of hygroscopic materials, e.g., Isolina has a thick paper meant to be used with their linoleic insulation.
I feel satisfied with this thread.. it is therefore not proven that the vapor barrier has any function in any way, but only causes problems that otherwise would have been avoided in the construction.
don't really know how to interpret it, but it doesn't sound like a compliment
So, it's basic physics. It's fairly simple to calculate theoretically that the diffusion plastic is needed. There is indeed proof. What you're asking for are empirical "proofs," which are harder to come by.
The problem is that in theory the plastic is tight, but in practice it's not, because it's punctured in various places, poorly joined, etc.
So the question we should ask ourselves is whether a typical installation of diffusion plastic, as it usually looks today, is better or worse than none at all? Here I am convinced that the answer depends on the thickness of the insulation. The thicker the insulation, the greater the need for plastic.
I am completely convinced that plastic combined with negative pressure ventilation is an absolute must with today's insulation thicknesses. It's particularly sensitive in the first year/years after construction when all the building materials are drying out.
The problem is that in theory the plastic is tight, but in practice it's not, because it's punctured in various places, poorly joined, etc.
So the question we should ask ourselves is whether a typical installation of diffusion plastic, as it usually looks today, is better or worse than none at all? Here I am convinced that the answer depends on the thickness of the insulation. The thicker the insulation, the greater the need for plastic.
I am completely convinced that plastic combined with negative pressure ventilation is an absolute must with today's insulation thicknesses. It's particularly sensitive in the first year/years after construction when all the building materials are drying out.
The wallpaper paste found in most properties is diffusion-tight, heat is not a particle but a wave, which means that the physics is surpassed in the usual way and transitions to radiation that does not follow the behavior of a solid particle. So there is much we do not know when it comes to how moisture arises, how it behaves in different materials, etc. In my opinion, the heat passes through the vapor barrier and causes the cooler air to release its water vapor due to a collision between warm and cold air, resulting in vapor condensation in the insulation, Hammarby Sjöstad is a proof of this, the million program is another, newly built villas with similar problems, newly built multi-family houses one-step facades (okay, another type of problem), the list can go on indefinitely. But I didn't start this thread to get help with things I already know, but to get evidence (scientific) and no one has been able to upload such a thing or send it to me... therefore vapor barriers are a joke and a false phenomenon. If I am wrong, send me a document from KTH, Chalmers or Gävle or Örebro University. Then I will believe it is useful, otherwise it is a lie.
Well, it becomes a funny discussion. I don't know if my contribution makes any difference...
My conclusion from the above is;
1) Heavily punctured plastic sheeting is likely worse than none at all, as moisture can get in but not out.
2) Thick insulation of material that cannot buffer moisture or is not allowed to dry out will lead to moisture problems.
The question is whether the builders are good or bad at installing the sheeting, and whether it works just as well after, say, 30 years (with the natural aging and mechanical impacts it undergoes). If the execution of the sheeting is so poor that it doesn't fulfill its purpose, then it's more of a liability than an asset. But that doesn't mean it's not needed in a newly built house. I don't believe in the method with plastic sheeting and fiberglass, but I don't think you can simply remove the plastic, all else being equal, you have to change the entire construction method.
But the empirical method might show that in practice, the building method doesn't work. Just like how after 15 years of struggling, it was concluded that single-layer sealed facades only work in theory, not in practice. Like many other things in the world.
My conclusion is that in an old house built with planks and sawdust, you should avoid plastic sheeting and fiberglass because it's never possible (unless you gut the entire interior) to create a completely sealed envelope. The combination of materials creates even worse consequences of moisture damage.
In a new house, it might succeed, I don't know, it surely depends on the builders' attitude and competence. Personally, I don't think it works. That doesn't mean the sheeting doesn't have a function, if done correctly, it seems pretty clear what the intention was and that in theory, it should work great. Then, the fact that the thought process was "wrong" or just "economical" without considering the reality is a completely different matter...
By the way, my boots are 100% waterproof. Or they were, the first few years. Nowadays, I get wet on my feet. That doesn't mean boots don't work... When they are new. But I'd rather choose 15-year-old boots than 15-year-old rubber boots if I'm heading into the woods.
My conclusion from the above is;
1) Heavily punctured plastic sheeting is likely worse than none at all, as moisture can get in but not out.
2) Thick insulation of material that cannot buffer moisture or is not allowed to dry out will lead to moisture problems.
The question is whether the builders are good or bad at installing the sheeting, and whether it works just as well after, say, 30 years (with the natural aging and mechanical impacts it undergoes). If the execution of the sheeting is so poor that it doesn't fulfill its purpose, then it's more of a liability than an asset. But that doesn't mean it's not needed in a newly built house. I don't believe in the method with plastic sheeting and fiberglass, but I don't think you can simply remove the plastic, all else being equal, you have to change the entire construction method.
But the empirical method might show that in practice, the building method doesn't work. Just like how after 15 years of struggling, it was concluded that single-layer sealed facades only work in theory, not in practice. Like many other things in the world.
My conclusion is that in an old house built with planks and sawdust, you should avoid plastic sheeting and fiberglass because it's never possible (unless you gut the entire interior) to create a completely sealed envelope. The combination of materials creates even worse consequences of moisture damage.
In a new house, it might succeed, I don't know, it surely depends on the builders' attitude and competence. Personally, I don't think it works. That doesn't mean the sheeting doesn't have a function, if done correctly, it seems pretty clear what the intention was and that in theory, it should work great. Then, the fact that the thought process was "wrong" or just "economical" without considering the reality is a completely different matter...
By the way, my boots are 100% waterproof. Or they were, the first few years. Nowadays, I get wet on my feet. That doesn't mean boots don't work... When they are new. But I'd rather choose 15-year-old boots than 15-year-old rubber boots if I'm heading into the woods.
a collision between warm and cold air and then you get precipitation
sorry I couldn't help myself
btw.
Thanks for a good question
it used to work without plastic - very well, in fact
soon some plastic producer will probably jump on it and come up with "proof"
sorry I couldn't help myself
btw.
Thanks for a good question
it used to work without plastic - very well, in fact
soon some plastic producer will probably jump on it and come up with "proof"
The problem remains, many people are calling Boverket and asking what applies when it comes to the plastic bag. No one knows and the construction sector doesn’t want to change because they have been doing it this way for 30 years and it works... then it can’t be wrong, right? Today's houses stand for about 30 years before they start to deteriorate, etc. Yesterday's buildings still stand today without modern materials. My house, which I built, is completely without a plastic barrier and shows no signs of moisture in the walls (I only have 145*45 in the walls and 120 in the roof and use 2 KW convector heaters to heat 50 sqm). So I must have done something right. But according to the experts and the learned, my house doesn’t work, and I will get black mold after 2-3 years. It was 3 years ago I was supposed to get black mold... but I must have missed that.
hsd said:a collision between warm and cold air and then you’ll have precipitation
sorry I couldn’t resist
by the way.
Thanks for a good question.
it worked well without plastic before - very well indeed
soon some plastic producer will likely come with "evidence"
...but lots of people DO have problems with moisture and mold, so it doesn't work in practice...
But your question is whether it works in theory. And I do believe it does. I would be surprised if there isn't a scientifically written document explaining how the plastic film is supposed to work.
It's important to distinguish between theory and practice!
That your house works without film can depend on many things, including ventilation and how much moisture load you give it. I'm completely convinced that you can create a climate that will cause almost any house to suffer moisture damage. Maximum heat, constant showering and boiling water, and no ventilation. Build a little Japanese indoor spa in the living room where you serve freshly cooked rice to 20 sweaty sauna-bathing sumo wrestlers, and you'll see that none of the building methods we've discussed can prevent moisture damage... Now it's Friday!
But your question is whether it works in theory. And I do believe it does. I would be surprised if there isn't a scientifically written document explaining how the plastic film is supposed to work.
It's important to distinguish between theory and practice!
That your house works without film can depend on many things, including ventilation and how much moisture load you give it. I'm completely convinced that you can create a climate that will cause almost any house to suffer moisture damage. Maximum heat, constant showering and boiling water, and no ventilation. Build a little Japanese indoor spa in the living room where you serve freshly cooked rice to 20 sweaty sauna-bathing sumo wrestlers, and you'll see that none of the building methods we've discussed can prevent moisture damage...
Now it's Friday!