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.
You are overthinking this.
Regular mineral wool insulation is just as vapor-permeable and is usually more insulating and cheaper than wood wool.
Basically, the company is saying the same thing as I am: as long as the cold roof is kept, there’s no need to make it more complicated.
Regular mineral wool insulation is just as vapor-permeable and is usually more insulating and cheaper than wood wool.
Basically, the company is saying the same thing as I am: as long as the cold roof is kept, there’s no need to make it more complicated.
G
garfunkel11 Aug 2018 20:37I'm asking again out of curiosity.
Without a vapor barrier, moisture penetrates the insulation, where the dew point is located. The vapor condenses and water accumulates in the insulation. If everything is open to the outside, does this effect not occur?
Is the dew point bypassed in that case, or is that not possible?
Without a vapor barrier, moisture penetrates the insulation, where the dew point is located. The vapor condenses and water accumulates in the insulation. If everything is open to the outside, does this effect not occur?
Is the dew point bypassed in that case, or is that not possible?
I believe you are right—yes, moisture does get into the insulation and probably stays there.
However, in my opinion (I’m not a professional, just thinking out loud), if the roof is open and you have insulation that can absorb and release moisture, nothing bad will happen.
I think it depends on the type of insulation.
If you have insulation that cannot handle moisture properly, it’s useless and ineffective.
I also believe that if the roof is closed (with a membrane or something similar), insulation that absorbs and releases moisture would be a problem, because it would act like a wet sponge.
Don’t hate me—this is just how I imagine it!
Here is my shortened response:
So, “Yes, without a vapor retarder, moisture gets into the insulation whether the roof is open or not.”
The key is to find a way to remove this moisture, which probably only works with an open roof and insulation that won’t be damaged by moisture.
However, in my opinion (I’m not a professional, just thinking out loud), if the roof is open and you have insulation that can absorb and release moisture, nothing bad will happen.
I think it depends on the type of insulation.
If you have insulation that cannot handle moisture properly, it’s useless and ineffective.
I also believe that if the roof is closed (with a membrane or something similar), insulation that absorbs and releases moisture would be a problem, because it would act like a wet sponge.
Don’t hate me—this is just how I imagine it!
Here is my shortened response:
So, “Yes, without a vapor retarder, moisture gets into the insulation whether the roof is open or not.”
The key is to find a way to remove this moisture, which probably only works with an open roof and insulation that won’t be damaged by moisture.
garfunkel schrieb:
I'm asking again out of interest
Without a vapor retarder, moisture enters the insulation where the dew point is located. The vapor condenses and water collects in the insulation. If everything on the outside is open, does this effect not occur?
Is the dew point bypassed then, which can’t be, right?The first part is correct: moisture does enter, but it simply dries out again. In this case, the dew point is not within the insulation.
I can't exactly explain why, probably because it dries out too quickly, but the dew point is also shown in the U-value calculator if it falls within the building envelope.
Therefore, I would like to refer again to my schematic, which seems to fit well—it shows no dew point within the insulation.
G
garfunkel12 Aug 2018 10:30Yes, I have seen that already, and it just seemed strange to me that there is no dew point. But well, if it works that way, you can set it aside for now and focus on other things.^^
Similar topics