Walls in basement area - knowledge inventory anno 2012

[Michael86]

Then you usually don't have 200mm insulation + wall before the roller blind. I don't know what kind of windows you have. But with a new one with a good U-value, a regular roller blind doesn't contribute to condensation!

 

[ekolodet]

Regarding attaching to an exterior wall; it's not just capillary action that's a problem. Condensation against a cold exterior wall is one example

I agree with you regarding uninsulated walls below ground.
Our basement is insulated externally with 200mm Pordrän. The condensation points are in the insulation, and the water runs down to the drainage.
I've had all the walls "naked" since New Year's 2012. Even though the part above ground is uninsulated, the whole wall feels "evenly warm." We don't have any cold walls, and I've never seen any condensation on the inside.

I should perhaps add that by that I mean I don't think any possible moisture condenses between the exterior and interior walls. However, there is moisture.
The question is what this moisture might cause, and whether it's enough to leave a "gap" at the top and bottom as suggested.
As I said, I've read everything from "it doesn't work at all" to "tests show that air changes even behind the wall."

 

[stoif]

Then you usually don't have 200mm insulation + wall before the roller blind. I don't know what kind of windows you have. But a new one with a good U-value doesn't cause a regular roller blind to contribute to condensation!

As I probably wrote, I took an example to highlight the issue.

And furthermore, the roller blind increases the risk of condensation even with new windows. The fundamental problem is that warm air will be cooled down.

And it wasn't the entire wall that had 200mm insulation; above the ground, it was pure concrete hollow block or leca.

 

[stoif]

Agree with you regarding uninsulated wall below ground.
Our basement is externally insulated with 200mm Pordrän. The condensation points are out in the insulation, and the water runs down to the drainage.
I have had all walls "bare" since New Year 2012. Even though the above-ground part is uninsulated, the entire wall feels "evenly warm." We don't have any cold walls, and I've never seen any condensation on the inside.

I should perhaps add that by that, I mean I don't think any moisture would condense between the outer wall and the inner wall. However, there is moisture.
The question is what this moisture can cause, and if it's enough with the suggestion to leave a "gap" at the top and bottom.
As I said, I've read everything from "it doesn't work at all" to "tests show that air is also exchanged behind the wall."

That's exactly my point; it's not just below ground that this applies. Look at a cold attic, for example. It's about warm air cooling down, and in the worst case, it will condense.

If you set up studs, you'll also be lowering the temperature in the outer wall. Today, the temperature gradient towards the outdoor temperature starts on the inside of your outer wall. It will instead be on the inside of your studded wall.

It can work, but it can also cause problems. It of course depends on the temperature in the basement, outdoor temperature, humidity, circulation between the "walls" (a lot is not necessarily good).

I would guess that in your case, it will be fine, but that's just speculation.

 

[mycke_nu]

In our old limestone house from 1909, some rooms had inner walls installed in the 70s consisting of wooden studs and building panels.

Even though the limestone walls ventilate fairly well (they are just stacked stone and cracked plaster), the space between is quite junky and partly moisture-damaged. This is despite being on the ground floor, not in the basement, and the house being extremely drafty, i.e., well-ventilated.

In rooms where we've torn away the junk, it is very dry and nice, so personally, I would really hesitate to build inner walls in a basement.

Consider whether it might be possible to solve the acoustics with textiles or sound-absorbing ceilings instead.

 

[sepani]

Hello, I have applied a smooth plaster to 140 m2 in my basement of a house from the 1970s. Just like yours, it was previously a risk construction, but now all walls are smooth plastered about 2 cm on siporex that have been netted and primed, and now painted white, it turned out great, and from an insulation perspective, I don't notice any difference. We also use the basement as a "kids' room," and I hear minimal noise up to the second floor, even though we have a very open floor plan both upstairs and downstairs, with only one door to the "children's area." Of course, it isn't a "panic room," but maybe that's not what you want either? I've installed electrical etc. in the walls, and there were no problems. I will never install anything organic in the basement again. If I need additional insulation, I would use something like pordrän from the outside.

 

[kvistarn2]

Gypsum has a sound-absorbing ability. It is evident from the specification for gypsum, and if there is something I believe I can draw unambiguous conclusions from by posts on this forum, it is that gypsum has a sound-absorbing effect.

Double gypsum (or another sheet on the backside) reduces the risk of what is usually described as "bongo sound."

From my youth and time as a "garage musician," I remember the difference between the rehearsal room in the school's bomb shelter (just stone walls) and the youth club's rehearsal room (I guess it was standard gypsum walls).

And I can also do the final test by going down to one of the rooms in the basement, which now stands empty with bare walls. And sure, you can hear a faint "echo." It is not at all the same soundscape as it was before we tore down all the interior walls of gypsum and stone wool insulation.

That is not to say that it can't be solved even with plastered walls. There are other tricks to consider. I am inventorying all possibilities.

Putting up gypsum will not reduce the sound level in the room; the only thing it does is keep the sound in the room so it doesn't spread to other rooms. But in a basement, it feels very unnecessary since the walls are already heavy and massive and dampen sound better than gypsum. It echoes in every "gypsumed" room I've been in. If you read a bit on different hi-fi and sound forums, most seem to disdain gypsum walls for that reason also. We only have plastered walls in the basement, wall-to-wall carpet, a sofa, and other textiles that completely eliminate the echo without any problem, and I am quite picky since we have a cinema room down there.