Was blue concrete used as additional insulation?

[Dublin]

Currently renovating the basement in an old house from the early 1900s. The basement walls are 20-30 cm thick, cast with a lot of natural stone. In some of the rooms in the basement, the inside of the exterior walls has been clad with thin (about 7-8 cm) blocks of blåbetong.

Does anyone know why this was done? My own guess is that this was done long after the house was built. Could it be for additional insulation?

 

[Demmpa]

In our recreation room and in the stairs, there are blue concrete blocks on the inside of the exterior walls, but not on any other exterior wall.
Yes, lightweight concrete (e.g., blue concrete) is somewhat insulating.

 

[JanneJanne123]

Just guessing wildly now, but maybe someone wanted smooth walls and thought it was a convenient way?

 

[Dublin]

Wild guess, but maybe someone wanted smooth walls and thought it was a convenient way?

Yes, that could also be the case (in addition to any insulation effect), at the same time it must have been a bit tricky to put them up if the wall wasn't straight/even to begin with.

 

[Boende45]

Currently renovating the basement of an old house from the early 1900s. The basement walls are 20-30 cm thick, cast with a lot of natural stone in them. In some of the rooms in the basement, the inside of the exterior walls is lined with thin (about 7-8 cm) blocks of blue concrete.

Does anyone know why this was done? My own guess is that it was done long after the house was built. Could it be to add insulation?

Answer yes.

I have personally owned a house with all walls, exterior and interior, made of blue concrete. It was a cheap material that was also good at insulating compared to the alternatives.

 

[JanneJanne123]

Answer yes.

I have personally owned a house with all walls, exterior and interior walls, in blåbetong. It was a cheap material that was also well insulating compared to the alternatives.

But then it sounds more like that house had blåbetong instead of concrete blocks or similar, not that it was added to existing walls for insulation?

 

[Boende45]

But then it sounds more like that house had blue concrete instead of concrete block or similar, not that it was applied to existing walls for insulation?

Sure, that's one interpretation. What I wanted to say was that the outer walls lacked insulation, and yet it was the part of the building with the least heat leakage. The house was from 1958.

 

[Dublin]

I'm kind of tempted to tear out the blåbetongen when I renovate the basement. Haven't done a radon measurement though, but I don't feel like waiting for a measurement for a couple of months, and the demolition should be quick anyway. Do you think there will be any noticeable difference in insulation effect without the blåbetongen?

 

[Demmpa]

Did a small measurement, even though we have insulated the basement on the outside.

Got the following readings 0.5m above the floor;
Without blåbetong: 19.5°
With blåbetong: 19.7°
Room temperature: 20.2°

All measured with thermocouple type K & Honeywell 2020 calibrator.

 

[Dublin]

I did a small measurement, although we have insulated the basement on the outside.

Got the following measurements 0.5m above the floor;
Without blåbetong: 19.5°
With blåbetong: 19.7°
Room temperature: 20.2°

All measured with thermoelement type K & Honeywell 2020 calibrator.

Thank you That suggests there isn't much of an insulation effect. On the other hand, your insulation on the outside might make the base wall itself quite warm. The house I'm renovating is not insulated on the outside.

 

[Energisparspecialisten]

I am renovating the basement of an old house from the early 1900s. The walls in the basement are 20-30 cm thick, cast with a lot of natural stone. In some of the rooms in the basement, the inside of the outer walls has been dressed with thin (about 7-8 cm) blocks of blåbetong.

Does anyone know why this was done? My own guess is that this was done long after the house was built. Could it be for additional insulation?

I am renovating the basement of an old house from the early 1900s. The walls in the basement are 20-30 cm thick, cast with a lot of natural stone. In some of the rooms in the basement, the inside of the outer walls has been dressed with thin (about 7-8 cm) blocks of blåbetong.

Does anyone know why this was done? My own guess is that this was done long after the house was built. Could it be for additional insulation?

Blåbetong is poor insulation.

 

[petererlandsson1194]

It is most likely slag plates and not blue concrete. It was common in the 1930s, for example, to cover the inside of basement walls with it. Easy to track for electrical wiring or similar in these and probably easier to plaster the concrete behind.
Worthless if you want to screw up something heavier.
Even interior walls in basements are usually built with slag plates if they are not load-bearing.

 

[Dublin]

It is most likely slag plates and not blue concrete. Common in, for example, the 1930s to clad the inside of basement walls with it. Easy to trace for electricity and such in these and probably easier to plaster the concrete behind.
Useless if you want to screw something heavier up.
Even interior walls in basements are usually made of slag plates if they are not load-bearing.

What appearance characterizes slag plates? What I have is very typical for blue concrete, i.e., gray-blue towards the blue side - light and porous. Moreover, a short-term measurement showed high radon levels, so we will tear everything out.

 

[Stefan N]

Upload an image.

 

[Demmpa]

In the following article, there's some information about blåbetong and two pictures,
https://www.byggahus.se/renovera/blabetong-hus-fakta-atgarder

In the following post, there's a picture of how our blåbetong looks,
https://www.byggahus.se/forum/threads/blabetong-eller-ej.439826/#post-4555661
Another post with a picture of our blåbetong, during demolition,
https://www.byggahus.se/forum/threa...ed-era-hus-idag.167378/page-1644#post-3984014