Old building floor gives way - Danger?

Hello out there,

15 minutes ago I realized with horror that a depression has recently formed in the kitchen floor.

About the building itself: old building, condominium, from the 1950s or 1960s. The floor itself is made of wood, underneath there should be ash as insulation material, underneath that again wood, which forms the ceiling of the apartment one floor below.

Tiles are laid on the wooden floor. Some tiles got cracks quite some time ago, I always wondered where they came from. I attributed it to the wooden floor being flexible.

I noticed the depression already a few days ago and wondered why I never noticed it before. But just now I realized that a gap has formed between the tiles and the baseboards, which is about 3cm at its widest point.

I removed a tile at the edge of the depression some time ago, the wood underneath looks completely dry and undamaged.

Tomorrow I will remove a tile in the depression itself and have a closer look.

Do you have any tips for me? Or is this "movement" of the old building normal? What causes can it have? Is there even danger?

Thanks to you all for your answers

freid

Remote diagnoses of such building damages are not accurately possible, especially since information on the structural connections is also missing. These would have to be documented based on existing plans or determined on site during a building survey. The component structure of the ceiling construction would need to be known in order to make an assumption about the causes of the deformation. "Normal" are not structural movements that go beyond those caused by temperature and humidity changes, which should not play a role in your case.

For a building from the 50s/60s, I do not necessarily expect a wooden beam ceiling, but rather a - economical - concrete ceiling or a panel ceiling. If deformations of the raw ceiling were the actual cause, this would also be noticeable on the floor below and in fundamental "movements" in the building, i.e. crack formation.

If necessary, you should conduct an on-site inspection with an architect/structural engineer and at least open the ceiling at one location beforehand to clarify the structural composition and installation situation of the ceiling. It may also be necessary to assess the building as a whole if the deformation is not exclusively local in nature. For a wooden beam ceiling with plank floor construction, basically only moisture damage in the wall bearing area of the wooden beams or moisture damage in the plank floor due to leaking sanitary pipes (drip leakage) or siphon come into question.

Hello wpic,

first of all, thank you very much for your post.

I had a night shift last night and today I tore up the floor because I am terribly afraid that something might collapse.

Even though it is difficult to make a "remote diagnosis," I wanted to ask you once again if you could share any suspicion regarding the statics/collapse risk based on the new information I discovered today.

Because while tearing up the floor, I came across screed/concrete and suspect that this supports the floor and thus there is no risk of collapse.

Here are the facts:
Under the tiles in the newly formed depression, in an area of about 1 x 1 meter, all the wood is rotten, crumbly, and black. However, it is all bone dry. The previous tenant had his sink there. In my layman’s opinion, it is quite obviously an old water damage.
A crossbeam has burst as a result, and the depression has formed.

The construction of the floor is (from top to bottom):

Tiles
Chipboard (rotten in the affected area)
Wooden floorboards (rotten in the affected area)
Crossbeam (rotten in the affected area); spacing about 30-40cm
The crossbeams rest on smaller concrete blocks.
The concrete blocks lie on screed/concrete.
Under the crossbeams and between the smaller concrete blocks there is ash.

The apartment was an attic about 40 years ago and was then converted into an apartment. Next to the apartment there is an attic room (on the same floor as the apartment), which was also converted into living space last year and there is also load-bearing screed (an architect and a structural engineer looked at it) at exactly the same height. It is probably the "same" screed.

I am now totally exhausted, it would be great if you could write a few comforting words so I can sleep peacefully soon.

Kind regards

freid

My suspicion that leaking sanitary pipes could have caused this damage is almost confirmed. You should consult the architect who planned the rest of the attic extension about the floor structure of the ceiling beneath your floor and for safety also about structural details of the concrete ceiling (thickness, assumed load capacity for the statics in the building application).

If the shell construction is okay, your next step would be to tear out the entire old floor and have a proper new floor structure planned according to your requirements. (Impact) sound insulation plays a role here as does resistance to moisture. An old-fashioned plank floor would therefore not be the first choice. If you want to install sanitary installations in the floor area, they must be planned and not improvised by the executing company on site. Do not leave anything to the craftsmen.

I would almost recommend having a knowledgeable expert inspect your condominium - provided you are the owner and not a tenant. Such constructive "legacy issues" are always a sign that there has been shoddy work elsewhere or at least work not carried out according to recognized technical standards.

You can also ask the owner of the apartment for building documents. He must have received a building description upon purchase, containing meaningful detailed and material information about the renovation work carried out.

If you are only a tenant, you should not take any action and notify the owner; everything else is then not your concern.

Hello wpic,

thank you very much for your post. It's nice to see when knowledgeable people kindly take care of such problems.

As soon as I know something new, I'll write.

Best regards
freid