Good evening everyone,
I have a question here. Yes, I have already used Google probably a thousand times but haven’t found anything useful.
Let me start.
We bought a house built around 1960.
We want to insulate the ceiling of the top floor, either have it done professionally or possibly do it ourselves. I have a few things I would like to know about this.
About the construction
In the first section, the ceiling structure looks as follows:
- Drywall ceiling
\/
- Metal substructure for suspending
\/
- Vapor retarder
\/
- Attic (NOT WALKABLE and the roof is NOT INSULATED)
______________________________________________
In the second section, it is like this:
- Drywall ceiling
\/
- Wooden substructure
\/
- Wood wool boards or Heraklith (plastered)
\/
- Attic (NOT WALKABLE and the roof is NOT INSULATED)
Now the questions and problems.
As you have read, in the second section there is NO vapor retarder. Also, in the first section it must be assumed that the existing vapor retarder was probably not sealed properly at the wall connections (although I cannot say this for sure).
Now my question is, which insulation can we use if we insulate the top floor ceiling ourselves? We would basically need insulation that works without a vapor barrier.
My thought was to insulate with vapor open (breathable) materials.
For me, this means that if I buy vapor-open insulation and install it, then the water vapor should pass through the insulation and then escape through the roof tiles (since the roof is uninsulated).
I am not a professional, but is that roughly correct?
There is also capillary-active insulation, which I have heard absorbs some moisture and then releases it again. Do you know if there is perhaps a combination of both (capillary-active and vapor-open)?
Can you recommend insulation for this project?
Next year or the year after, we will have blown-in insulation installed in the ceiling of this floor, so if we insulate ourselves now, it would only be temporary, or if the DIY insulation works well, we might leave it as is.
But the same questions regarding vapor openness apply to the blown-in insulation.
Installing a vapor retarder afterwards is unfortunately no longer possible because the floors are already finished.
So here are the questions summarized:
1. Do I understand the concept of vapor openness correctly?
2. Do I understand capillary-active insulation correctly?
3. Which insulation could we use to insulate the top floor ceiling?
4. To remain vapor open, is it enough that, when the roof is replaced, only part of the roof slopes are insulated (basically starting from below up to the height of the floor ceiling insulation)?
5. Is the build-up in the “second section” okay with drywall > cavity > wood wool boards, or could condensation occur that might damage the drywall or the boards?
I hope you can help me a little with this.
Sorry for the long text; I hope the information is sufficient.
I have a question here. Yes, I have already used Google probably a thousand times but haven’t found anything useful.
Let me start.
We bought a house built around 1960.
We want to insulate the ceiling of the top floor, either have it done professionally or possibly do it ourselves. I have a few things I would like to know about this.
About the construction
In the first section, the ceiling structure looks as follows:
- Drywall ceiling
\/
- Metal substructure for suspending
\/
- Vapor retarder
\/
- Attic (NOT WALKABLE and the roof is NOT INSULATED)
______________________________________________
In the second section, it is like this:
- Drywall ceiling
\/
- Wooden substructure
\/
- Wood wool boards or Heraklith (plastered)
\/
- Attic (NOT WALKABLE and the roof is NOT INSULATED)
Now the questions and problems.
As you have read, in the second section there is NO vapor retarder. Also, in the first section it must be assumed that the existing vapor retarder was probably not sealed properly at the wall connections (although I cannot say this for sure).
Now my question is, which insulation can we use if we insulate the top floor ceiling ourselves? We would basically need insulation that works without a vapor barrier.
My thought was to insulate with vapor open (breathable) materials.
For me, this means that if I buy vapor-open insulation and install it, then the water vapor should pass through the insulation and then escape through the roof tiles (since the roof is uninsulated).
I am not a professional, but is that roughly correct?
There is also capillary-active insulation, which I have heard absorbs some moisture and then releases it again. Do you know if there is perhaps a combination of both (capillary-active and vapor-open)?
Can you recommend insulation for this project?
Next year or the year after, we will have blown-in insulation installed in the ceiling of this floor, so if we insulate ourselves now, it would only be temporary, or if the DIY insulation works well, we might leave it as is.
But the same questions regarding vapor openness apply to the blown-in insulation.
Installing a vapor retarder afterwards is unfortunately no longer possible because the floors are already finished.
So here are the questions summarized:
1. Do I understand the concept of vapor openness correctly?
2. Do I understand capillary-active insulation correctly?
3. Which insulation could we use to insulate the top floor ceiling?
4. To remain vapor open, is it enough that, when the roof is replaced, only part of the roof slopes are insulated (basically starting from below up to the height of the floor ceiling insulation)?
5. Is the build-up in the “second section” okay with drywall > cavity > wood wool boards, or could condensation occur that might damage the drywall or the boards?
I hope you can help me a little with this.
Sorry for the long text; I hope the information is sufficient.
@dertill Yes, I have also thought about installing the vapor retarder from above.
Basically, the ceiling is just a type of wooden paneling, so you could attach the vapor retarder there.
My only concern is that I won’t be able to seal the spots where cables run from below to above.
I’m also worried about the wooden beams; wouldn’t they absorb moisture from underneath as well?
Why isn’t there simply insulation that comes wrapped in vapor retarder film, or with a film attached on the underside?
@apokolok Yes, that’s basically how I imagined it too. You just have to make sure the insulation is vapor permeable and can handle a bit of moisture. (Wood fiber insulation would be the right choice here, wouldn’t it?!)
Basically, the ceiling is just a type of wooden paneling, so you could attach the vapor retarder there.
My only concern is that I won’t be able to seal the spots where cables run from below to above.
I’m also worried about the wooden beams; wouldn’t they absorb moisture from underneath as well?
Why isn’t there simply insulation that comes wrapped in vapor retarder film, or with a film attached on the underside?
@apokolok Yes, that’s basically how I imagined it too. You just have to make sure the insulation is vapor permeable and can handle a bit of moisture. (Wood fiber insulation would be the right choice here, wouldn’t it?!)
kayshle schrieb:
I’m just worried that I won’t be able to properly seal the spots where cables go from the bottom to the top.This is not a major issue since the attic provides enough ventilation for drying. However, I wouldn’t do it without at least a vapor retarder.
kayshle schrieb:
I’m also concerned about the wooden beams. Won’t they absorb moisture from below?That’s why it’s best to insulate “from below.” If you place an additional layer of insulation over the beams, the dew point should remain outside the structure.
kayshle schrieb:
Why isn’t there just insulation wrapped in vapor barrier foil or with a foil attached on the underside?In the past, there were mineral wool insulation panels with aluminum facing. They might still be available. The problem was that they were often installed the wrong way around, and especially at connection points the continuous layer was missing. A continuous membrane solves this better. If you can still get them from a building materials supplier, that could be an option. But don’t use two layers! If you do, the top layer should be without facing.
G
garfunkel11 Aug 2018 10:52Can what apokolok presented really work?
It would be new to me that there are constructions without a vapor barrier, even if the ventilation is excellent.
It would be new to me that there are constructions without a vapor barrier, even if the ventilation is excellent.
The technical standards assume that the attic space could potentially be used as living space later on.
In that case, you definitely need to take a very different approach.
But if it's just about insulating the ceiling and the attic is completely unused, with the roof well-ventilated because it has no insulation, what exactly could go wrong?
Moisture rises and is ventilated out. Even if it becomes a bit more humid up there, there is nothing that could be damaged. The insulation itself is the only thing I can think of that might be at risk. However, due to the ventilation, it is not endangered either.
You could also install an airtight membrane below, as already suggested, but achieving a truly airtight seal won’t be easy.
So, I would save yourself the trouble, just put in insulation wool and leave it at that.
In that case, you definitely need to take a very different approach.
But if it's just about insulating the ceiling and the attic is completely unused, with the roof well-ventilated because it has no insulation, what exactly could go wrong?
Moisture rises and is ventilated out. Even if it becomes a bit more humid up there, there is nothing that could be damaged. The insulation itself is the only thing I can think of that might be at risk. However, due to the ventilation, it is not endangered either.
You could also install an airtight membrane below, as already suggested, but achieving a truly airtight seal won’t be easy.
So, I would save yourself the trouble, just put in insulation wool and leave it at that.
C
Caspar202011 Aug 2018 12:05kayshle schrieb:
We want to insulate the top floor ceiling here, either by having it done professionally or possibly doing it ourselves.How would a professional have done it?
kayshle schrieb:
Next year or the year after, we will have blown-in insulation installed in the ceiling of the upper floor. So, if I insulate it myself now, it’s just a temporary solution, or if the DIY insulation works well, we might leave it as is.Huh? Is the same work going to be done again?
kayshle schrieb:
We can’t be the only house that’s finished but can’t be insulated without having to tear everything out.As harsh as it sounds; it wouldn’t really be finished until it was properly done right away.
@Caspar2020
The company would also install it without a vapor barrier since there is no other option now.
They also said it should be done with vapor-permeable insulation materials, and if the roof is being redone, it’s important to keep it as a ventilated roof on the upper side so that moisture can escape.
Of course, the problem is that moisture will penetrate the insulation one way or another, whether it’s vapor-permeable or not. But this is exactly where wood fiber insulation could help because it can absorb a significant amount of moisture and release it later.
As I said, the roof currently has only tiles, no membrane or anything else. So the moisture should be able to dissipate sooner or later without any problems.
What do you think about wood fiber insulation, and why might it not work? Are there any reasons against it?
Regarding the comment about doing it properly from the start, that’s easier said than done. When we bought the house, it was already fully renovated except for the furniture—it was all finished. I don’t think anyone would have gutted everything just to install a membrane.
The company would also install it without a vapor barrier since there is no other option now.
They also said it should be done with vapor-permeable insulation materials, and if the roof is being redone, it’s important to keep it as a ventilated roof on the upper side so that moisture can escape.
Of course, the problem is that moisture will penetrate the insulation one way or another, whether it’s vapor-permeable or not. But this is exactly where wood fiber insulation could help because it can absorb a significant amount of moisture and release it later.
As I said, the roof currently has only tiles, no membrane or anything else. So the moisture should be able to dissipate sooner or later without any problems.
What do you think about wood fiber insulation, and why might it not work? Are there any reasons against it?
Regarding the comment about doing it properly from the start, that’s easier said than done. When we bought the house, it was already fully renovated except for the furniture—it was all finished. I don’t think anyone would have gutted everything just to install a membrane.
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