ᐅ Soundproofing a soil stack pipe running through the open-plan kitchen-living area

Hello dear forum,

About two weeks ago, my family and I took over our new single-family home from a developer near Lüneburg.

Now that we are slowly moving in and the kitchen will be delivered soon, we noticed that a soil pipe in the exterior wall of the open-plan kitchen might not be properly soundproofed.

Above the kitchen is our bathroom. When we visited the house during the shell construction phase, I noticed that a soil pipe runs through the exterior wall from the kitchen into the foundation slab.

The pipe first goes down vertically about 20cm (8 inches), then horizontally about 70cm (28 inches), and then vertically again into the foundation slab. I seem to remember that the pipe was white, and something about it being a “sound-insulated pipe” was mentioned. From my research, it could be a Skolan pipe.

The pipe is partially wrapped in a red casing and fixed with a nail strip – which probably increases sound transmission, right? Also, I’m quite certain that the horizontal section is just a regular gray PVC pipe (HT pipe) and not a white, sound-insulated one.

When flushing the toilet upstairs, it sounds like water rushing through the entire wall down in the kitchen. Could this have been better insulated? And would you consider this a defect?

Looking forward to your opinions!

Best regards

We also have this in the renovated kitchen, but basically only at a height of 100 cm (40 inches), meaning:

- Above that are the wall cabinets
- Below are the countertop and base cabinets

In front of it—in the old kitchen—there used to be a pull-out pantry, so you hardly noticed it at all. Now it’s just these 100 cm (40 inches) or so, and it doesn’t bother me in the slightest when the flush valve is up there.

Herbert67 schrieb:

Could this have been insulated better? And would you consider this a defect?

Yes and no.

Assuming you have a guest restroom downstairs and therefore rarely use the upstairs bathroom except when it’s completely quiet downstairs, it wouldn’t really bother me much either.

Wow, thanks for the quick responses! So I understand that you wouldn’t take any further action there.

Just out of curiosity: How could that have been properly insulated?

Herbert67 schrieb:

Wow, thanks for the quick responses! So I understand that you wouldn’t take any further action.

Just out of curiosity: How could this have been properly insulated?

- Use soundproof pipes
- Use acoustic pipe clamps
- Insulation around the pipe with high density material (e.g., mineral wool like Rockwool Conlit 150U — these are pipe shells) / alternatively, Armaflex works (not the most professional solution but effective) / if there is a boxing or enough space, fill with mineral wool

It is important to decouple the pipes from the walls as much as possible. Standard pipe clamps or nail strips are counterproductive.

Herbert67 schrieb:

The pipe goes about 20 cm (8 inches) vertically down first, then about 70 cm (28 inches) horizontally, and then vertically again into the floor slab.

That is also a design mistake...

Herbert67 schrieb:

Just out of curiosity: How could this have been properly insulated?

Ideally, the wastewater pipes should not be routed through the living spaces.