Hello everyone,
I often read about the concept of "breathing walls."
Statements like:
- "We were told not to insulate because otherwise my 31cm (12 inch) brick wall won’t be able to breathe anymore."
- "We don’t need a ventilation system; the timber frame wall has no membrane, so it can breathe well."
- "We have a vapor-permeable wall, so moisture can escape outside, and I don’t need a ventilation system."
- "The wall is vapor-permeable, a ventilation system is not necessary, and you basically don’t need to ventilate."
I keep seeing these and similar sentences online and have even heard them personally from house building companies—the latest just this Monday. Other opinions include: Don’t put photovoltaics on the roof due to too much electromagnetic pollution. He would never install a ventilation system. Climate change? That doesn’t even exist. At some point, I just got up and left.
I’m an engineer, not involved in house building. But in my opinion, these statements make no sense at all.
A wall can never really "breathe" properly.
Here, "breathing" means a significant moisture exchange.
How is this supposed to work physically? It’s not a thin membrane, but a thick, solid wall or one filled with insulation.
Sure, a certain amount of moisture transfer always occurs. But in my view, this is absolutely negligible. There is no way that the few liters of moisture produced daily in a single-family house could pass through the wall to the outside without either a ventilation system or manual ventilation. Physically, this just can’t happen.
Of course, it’s different with older houses. They have numerous leaks that allow air and moisture exchange. But modern houses are sealed tightly. Therefore, there is no real air exchange through the walls.
And beyond the aspect of "removing moisture to the outside," there is also the aspect of "bringing fresh air into the house."
My point is not to argue for or against ventilation systems. I am in favor, but it can also work without one if you don’t want it—just with regular manual airing, in my opinion.
What do you think? Do these "breathing walls" really exist?
Am I completely wrong? Or is this myth just incredibly persistent among home builders and even building companies?
Best regards,
Specki
I often read about the concept of "breathing walls."
Statements like:
- "We were told not to insulate because otherwise my 31cm (12 inch) brick wall won’t be able to breathe anymore."
- "We don’t need a ventilation system; the timber frame wall has no membrane, so it can breathe well."
- "We have a vapor-permeable wall, so moisture can escape outside, and I don’t need a ventilation system."
- "The wall is vapor-permeable, a ventilation system is not necessary, and you basically don’t need to ventilate."
I keep seeing these and similar sentences online and have even heard them personally from house building companies—the latest just this Monday. Other opinions include: Don’t put photovoltaics on the roof due to too much electromagnetic pollution. He would never install a ventilation system. Climate change? That doesn’t even exist. At some point, I just got up and left.
I’m an engineer, not involved in house building. But in my opinion, these statements make no sense at all.
A wall can never really "breathe" properly.
Here, "breathing" means a significant moisture exchange.
How is this supposed to work physically? It’s not a thin membrane, but a thick, solid wall or one filled with insulation.
Sure, a certain amount of moisture transfer always occurs. But in my view, this is absolutely negligible. There is no way that the few liters of moisture produced daily in a single-family house could pass through the wall to the outside without either a ventilation system or manual ventilation. Physically, this just can’t happen.
Of course, it’s different with older houses. They have numerous leaks that allow air and moisture exchange. But modern houses are sealed tightly. Therefore, there is no real air exchange through the walls.
And beyond the aspect of "removing moisture to the outside," there is also the aspect of "bringing fresh air into the house."
My point is not to argue for or against ventilation systems. I am in favor, but it can also work without one if you don’t want it—just with regular manual airing, in my opinion.
What do you think? Do these "breathing walls" really exist?
Am I completely wrong? Or is this myth just incredibly persistent among home builders and even building companies?
Best regards,
Specki
hampshire schrieb:
Addendum: If you want to ensure a pleasant experience in your home, it makes sense to avoid using materials that have unpleasant odors.To add to this: of course, this only applies to materials that are not sealed airtight. For example, whether an insulation system is made from rose petals or dead rats, you won’t notice it inside the house itself.
It is much more important to carefully choose the furniture in your home: wall paint, flooring materials, furniture like sofas, chairs, tables, beds, and so on.
N
nordanney6 Mar 2020 10:58Davidoff86 schrieb:
If you, or others, can explain to me with reasonable arguments why solid wood is NOT climate-regulating, I am happy to listen. Many people have already written about this. Modern houses are built to be (completely) airtight. Therefore, there is no exchange of moist or used air. The walls of your climate house are just as solid and airtight as those of stone houses. Wood may absorb some humidity, but so does plaster (as long as the walls are not sealed with latex paint, wallpaper, etc.). How the odors from occupants or the kitchen are supposed to be filtered without any air exchange is beyond me. Even if solid wood can absorb moisture, its capacity would eventually be exhausted (similar to a car air freshener or a kitchen exhaust hood).
These are all nice marketing promises. However, belief in them for houses is much stronger than for everyday products—turn on the television and watch the claims in commercials. No matter what it is—cured of a cold in two days, cleaned with a single wipe, or paper towels that never tear, all the way to rejuvenating facial creams (which, of course, only the 18-19-year-old models in the ads use).
You can live comfortably in a wooden house. But that is true for any other well-designed house as well.
What I can confirm is the positive effect of clay plaster. The plaster does actually absorb some moisture and slowly release it again. However, you still need to ventilate the bathroom.
What I can also confirm is the "breathability" of old cottages. I bought my current temporary apartment with breathable = leaky construction. After a major renovation with airtight windows and a new front door, the apartment suddenly feels stuffy. Ventilation is suddenly necessary again.
D
Davidoff866 Mar 2020 11:03Thank you for your post, @nordanney. I see that ventilation is a key issue. I will follow up with the supplier and will be happy to share their response.
H
hampshire6 Mar 2020 11:21Some things are simply easier than they seem: Just open the windows regularly.
Davidoff86 schrieb:
I see that ventilation is a crucial point.And don't forget to heat in winter. It is just as important as ventilation.D
Davidoff866 Mar 2020 11:28Mycraft schrieb:
And in winter, don’t forget to heat. That is just as important as ventilation. Congratulations, @Mycraft. Only two posts here, but very meaningful and factual.
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