Why did the ceiling sink, took down interior wall

[Utsliten och utdömd]

The reason for the asymmetry is because there is an eaves overhang on the right in the picture. You never want a load/support over a free part of the underarm, so they have added an extra strut to help bear the load at the support.
On the left side, the support is out where the upper arm and underarm meet, so the extra strut in the framework is not needed there.

Answering myself, but this is one of several reasons why this wall was not load-bearing. The design of the roof truss right at the interior wall indicates that the truss is not built to take a load in the form of a support there.

Then the fact that it was built with 50x35 studs sparsely distributed, moreover not aligned with joists or trusses, which requires a double board in the sill and wall plate with offset joints that seem to have been missing.

 

[Stefan1972]

a cm is hardly going to mean anything in that way...........Houses and foundations move and has anyone measured if the floor is at exactly the same level as when the house was built? To the millimeter? Or that the person who nailed the wall didn't cut the studs a little too long and hammered them in? It would be different if the roof sank 5cm........then you can start wondering......

 

[hydrolift]

Has TS checked to see if it's just the ceiling panels that have loosened a bit? In our Gullringen house, the ceiling tiles are just stapled and bent a centimeter when the additional insulation pushed on them. They are really marginally built houses. 😁

 

[cpalm]

The section probably shows two different types of trusses depending on where the right support is located. There is a different span for the living room part compared to the bedroom part.

Yes, that's probably how it should be interpreted, even if it is implied that the third diagonal only exists at the overhang.

 

[Gullringen]

Has the original poster checked if it's just the ceiling that has dropped a bit? In our Gullringen house, the ceiling tiles are only stapled and bowed a few centimeters when the additional insulation pushed on them.
They are truly marginally built houses. 😁

I'm not completely sure right now if it could be the ceiling that's sagging a little...

But one thing stated in the drawings is that the ceiling panel should be installed before the walls are erected. Which should also indicate that no interior walls are load-bearing...

 

[Gullringen]

Answering myself, but it's one of several reasons why this wall wasn't load-bearing. The design of the roof truss exactly at the interior wall indicates that the roof truss wasn't built to take a load in the form of a support there.

Furthermore, it was built with 50x35 studs sparsely distributed, and not aligned with the floor joists or rafters, which requires a double board in the base plate and top plate with staggered joints, which seem to have been missing.

I found a comment in the drawings stating that the interior ceiling paneling should be nailed before the walls are erected. This should also indicate that the interior walls aren't load-bearing...

 

[Ryzen]

Not directly relevant to this case, but worth mentioning. Our house is an over 100-year-old wooden house with a tile roof, and we were going to renovate the roof. It turned out that the roof had a slight 'sag' along the long sides about 1 m above the eaves, several cm. Therefore, we had to adjust new bargeboards and waterboards (metal) for this. Quite normal for this to happen apparently.

When you replace the roof, you adjust it so that the tiles lie perfectly.
That's what more serious roofers do.
Unfortunately, you often see the opposite. Not a single line is straight.

 

[-MH-]

1 cm in a 70-year-old house is within the margin of error.

 

[VidarH]

If I am to dust off my drafting skills from high school as well...
What I see is a façade drawing, a floor plan drawing, and a cross-section according to the markings. No construction drawings with building instructions to meet requirements. Cross-section in the situation only tells how it looks right there. Standards and practices (as I remember them) should indicate that it is a self-supporting roof structure with beams adjusted according to the situation to transfer the load down through the recessed exterior wall at the balcony to the extra wall in the basement...
It is, of course, possible to double and build in noggings in the floor joists to accommodate shifted loads, but that is an extra cost that I don't think they wanted to take for an interior wall to be placed 30-40 cm to the side...
So I would have done the same thing in that situation.
Moreover, it turned out that the wall wasn't load-bearing but was providing support due to age, if I understand correctly?

 

[Huddingebo]

1 cm in a 70-year-old house is within the margin of error.

If it stops there.
It will not stop there. Creep is a concept that also happens with wood under load and over time.

 

[-MH-]

Yes, and I see no problem with it having creeped 1 cm in 70 years. Or that the foundation has settled 1 cm in 70 years.

 

[Huddingebo]

Yes, and I don't see a problem with it creeping 1 cm in 70 years. Or that the foundation has settled by 1 cm in 70 years.

Ohh...
The wall has effectively prevented creeping for 70 years.
It is now starting. 1cm initially means it will continue.

It's like when you place a 5m long plank between two points.
Initially, it sags a bit. Wait a year and you'll see a completely different deflection.
If you had an extra support point between the resting points, the sagging would have been avoided.

 

[13th Marine]

So free-spanning roof trusses are just a myth and don't work?

 

[-MH-]

The other parts of the truss where it has been "hanging freely," how much have they bent down over 70 years?

Wow...
The wall has effectively prevented sagging for 70 years.
Now it's starting. 1cm initially means it will continue.

Oh, so it settled 1 cm in one day and you think it will continue at about the same pace? So by New Year's, we'll be crawling through the room? Or what should we expect by New Year's, how much extra do you think it will have settled?

You can't say anything about its behavior based on what happened suddenly.

 

[Huddingebo]

The other parts of the roof truss where it has "hung freely," how much have they sagged in 70 years?

Oh, so it settled 1 cm in one day and you think it will continue at about the same pace? So by New Year's, you'll be crawling in the room? Or what should we expect by New Year's, how much extra do you think it will settle?

You can't say anything about how it behaves based on what happened suddenly.

I considered creep and sagging a lot when I sized the joists over the kitchen where the span is just over 5m.
Measured a bit continuously during the first years and saw how the phenomenon faded away. But it was decently sized, and the load increases, if I remember correctly, in square to the span.

"Creep" in relation to wood refers to the slow, permanent deformation that occurs when the material is subjected to a constant load over time, an effect exacerbated by changes in the wood's moisture. It's important not to confuse this with changes in the wood's moisture content, which leads to shrinking when drying and swelling when absorbing moisture, or with attacks by "woodworm", which are larvae of wood-boring beetles.

Creep due to load

• What it is:
  When a wooden structure is subjected to a constant weight, like a load on a beam, the wood will bend more and more over time, even if the weight does not increase.
  
  
• The role of moisture conditions:
  Creep increases significantly when the wood's moisture content increases, and variations in moisture lead to even greater deformations than a constant moisture level.
  
  
• Effect:
  If the load is sufficiently high and prolonged, the creep can ultimately lead to the material failing.

Moisture movements (shrinking and swelling)

• What it is:
  Wood is a hygroscopic material that can absorb and release water vapor from the air, causing it to swell when absorbing moisture and shrink when drying.
  
  
• Impact:
  The moisture movements affect the dimensions of the wood, for example, a wooden floor can shrink and form gaps under dry conditions and swell when humid.

Difference between creep and moisture movements

• Creep:
  A deformation caused by constant load, where moisture plays an exacerbating role.
  
  
• Moisture movements:
  Changes in the wood's dimensions (shrinking/swelling) due to absorption and release of moisture.

Important to consider

• Designers must take into account both long-term creep and the effects of moisture variations when sizing wooden structures to ensure they do not deform excessively."

One can measure twice a year and plot a curve on graph paper to see where it is heading.