Question about insulation - getting more and more confused

[Tomture61]

It doesn't really matter for the mineral wool walls that there is timber in the house. I would like an explanation as to why it is not comparable.

I recommend you to read up on buildings built in different ways, I don't have the time to teach you how this and that works.
Personally, I have had a great interest for at least 30 years in the building one lives in + what is better/worse.

 

[arkTecko]

That's just nonsense.
The normal 15 degrees usually recommended by insurance companies is to withstand power outages without pipes freezing.

There are plenty of summer houses without electricity or that are shut down in winter without the consequences you mention. Insulation doesn't affect the house if there's no temperature difference across the wall.

Daniel, you repeatedly miss that conditions are not static. For example, there can be many hours in the morning/forenoon (or many days during weather changes) when it is significantly colder indoors than outside in winter in a shut-down house. This can likely also occur when outdoor humidity is very high.

 

[Daniel 109]

I recommend that you read up on buildings constructed in different ways, I don't have the time to teach you how such and such works.
Personally, I have had a great interest in the building you live in + what is better/worse every day for at least 30 years.

I have read a bit and believe I have a better understanding of the physics behind it than most.
But if you don't want to explain the big difference, you don't have to.

 

[Tomture61]

I have read quite a bit and believe I have a better understanding of the physics behind it than most.
But if you don't want to explain the big difference, you don't have to.

Then explain yourself what you know about the difference between a timber road vs. Tex ångbroms.

 

[Daniel 109]

Now, it was not the timber wall that was the interesting part in this case. It clearly has different properties than a stud wall with mineral insulation. But now it was about the stud wall. We can skip the environment in the house for now.

 

[Tomture61]

Now it wasn't the timber wall that was the interesting part in this case. It clearly has different properties than a stud wall with mineral insulation. But now it was the stud wall that was the topic. We can skip the environment in the house for now.

Your response to my statement says something else!

 

[Daniel 109]

Daniel, you repeatedly miss that the conditions are not static. For instance, there can be several hours in the morning/forenoon (or many days during weather changes) when it is significantly colder indoors than outside in a cold-conditioned house during winter. This is likely to also occur when the humidity outside is very high.

It is rarely significantly colder indoors. If it occurs, the opposite is also true, and then the moisture is driven in the other direction.

 

[arkTecko]

Significantly colder inside is rare. If it does occur, the opposite is true as well, where moisture is driven the other way.

Consider a situation with two weeks of high pressure and 15 degrees below zero, then a change in weather with rain, wind, and 5 degrees above zero for a week. I would not want to have a cold-set cabin with a moisture barrier and mineral wool insulation. The flaw in that construction is that relatively large amounts of water condense in the wall, and it takes significantly longer for the water to escape. It doesn't help if it gets cold outside again. No warm, dry air from inside can pass through the moisture barrier, and the cold, dry outside air in the next high pressure can't carry much moisture. Additionally, mineral wool is not hygroscopic, so it doesn't transport moisture out by itself like cellulose insulation does.

I would never build like that, and I advise others not to do it.

 

[Liljeros]

I think it's somewhat overestimated how much moisture pressure a wall in an unheated house actually experiences under the temporary condition when it's warmer outside than inside. That's probably why this rarely becomes a problem in a vacation home with mineral wool. The cellulose manufacturers emphasize the hygroscopic properties of their insulation quite a bit, and it is correct that they can absorb some moisture, which mineral wool does not do. However, moisture can still pass through mineral wool and as long as it's in vapor form, this is not an issue.

My in-laws have a vacation home insulated with mineral wool and without an external air gap or internal vapor barrier, which becomes a problem when the moisture that runs down the inside of the panel seeps into the insulation and the framework. This is what could be called a horror example since the facade is also painted with plastic paint, yet the house still stands. The paneling is probably closer to 30 years old in some places, and there aren't even tendencies of odor in the house, but when you remove boards, it hasn't been a pleasant sight.

 

[klaskarlsson]

Reverse moisture migration is primarily something that occurs in unheated cottages, right? It would take very extreme weather phenomena for this to occur in a heated villa.

Regarding cellulose insulation's ability to absorb and release moisture, this is something that can be positive mainly in an unheated attic and thus evens out humidity where it is relatively free and open. In a regular heated wall, air is transported from the inside out, so indoor moisture addition should be very limited...

The only situation apart from old houses where a vapor retarder is technically preferable is in roof constructions without an air gap where the possibility of drying inward might be needed at certain times of the year.

The thread starter does mention that the house will be unheated now and then.

 

[witten]

I read this on a site that sells/manufactures cellulose insulation "Cellulose has many properties that make it great as insulation. It absorbs moisture, which prevents moisture problems and also means that diffusion plastic is not needed when building."

[link]

I wonder if they are lying!

They are greatly exaggerating the benefits of the buffering properties as you can see from the measurements in this study.

https://vpp.sbuf.se/Public/Documents/ProjectDocuments/E85F90FA-3BAD-456B-9E5F-8B36FB53E112/FinalReport/SBUF 03199 Slutrapport Fuktbalans i kalla vindsutrymmen.pdf

Particularly clear is the lack of practical effect during the cold winter months when the RH in the attics studied is almost identical between the attic with cellulose insulation and mineral wool. These measurements are also made with a vapor barrier; without it, the RH would be even higher. The choice of insulation material affecting the moisture content in indoor air is completely dismissed.

 

[Tomture61]

The study is 27 years old!
Now it states that wood has moisture-absorbing properties.
Paper is made from wood.
I wonder if cellulose insulation has been product developed over 27 years.
Then the study was done on an attic.
Not that the whole house is insulated with cellulose insulation.

 

[arkTecko]

They greatly exaggerate the benefits of the buffering properties, as you can see from the measurements in this study.

[link] 03199 Slutrapport Fuktbalans i kalla vindsutrymmen.pdf

Especially evident is the lack of practical effect during the cold winter months when the RH in the attics studied is almost identical between the attic with cellulose insulation and mineral wool. These measurements are also made with a vapor barrier; without it, the RH would be even higher. The choice of insulation material affecting the moisture content of indoor air is completely dismissed.

I find it hard to see what this study has to do with the case in question?