Why did the ceiling sink, took down interior wall

[Gulldus]

I don't think those roof trusses look the least bit self-supporting.
Would they handle a 7-8m free span?

If it sank 10mm initially, it will definitely continue to sink.

I consider it a typical example of a self-supporting truss roof truss, manufactured without problems to be self-supporting for larger spans than what is relevant here.

 

[Kane]

I don't think those trusses look the least bit self-supporting.
Would they handle a 7-8m free span?

If it sank 10mm initially, it will definitely continue to sink.

Here you find facts. From the truss book.

 

[Huddingebo]

I consider it a typical example of a free-spanning truss, manufactured without issue to larger spans than what is relevant here

Yes, and what are you trying to say with that?
I've never claimed that it's not possible to construct free-spanning trusses. Of course, it is.
I have built such in the snow zone of southern Lappland with similar spans as the house in question here.

 

[Huddingebo]

Here you will find facts. From the truss book.[image][image]

Yes, that's how it usually looks.
I have books with such tables at home. Both older and some semi-new (1980s)

 

[GoC]

Yes, that's usually how it looks. I have books with such tables at home. Both older ones and some semi-new ones (from the 80s)

Your first comment on the topic
“I don't think those trusses look the least bit free-spanning.
Would they manage a 7-8m free span?”

 

[Huddingebo]

Your first comment on the subject
"I don't think those trusses look the least bit self-supporting.
Would they manage a free span of 7-8m?"

Yes, calculate the dimensions and consider the effects of how the different beams are connected to each other and see if they meet today's requirements for fully self-supporting trusses. The design is one thing, the sizing is completely another...

 

[13th Marine]

@Gullringen which snow zone are you in? And can you measure the dimensions of the upper frame and lower frame? (if you don't have it in any drawing)

 

[GoC]

Yes, calculate the dimensions and consider the effects of how the different beams are joined together to see if they meet today's requirements for fully self-supporting roof trusses.
The design is one thing, the dimensioning is quite another...

Now, surely it was the requirements from the day they were constructed that were applicable.
I would guess that the material in today's roof trusses is weaker than those that were nailed together on site back then.
Naturally, there are also roof truss drawings that the builders used. They indicate how they should be joined and with how many nails, etc.

 

[Huddingebo]

Now, it was still the requirements on the day they were constructed that applied.
I would guess that the material in today's roof trusses is slimmer than those that were nailed together on-site back then.
There are, of course, also roof truss drawings that builders used. These indicate how they should be joined and with how many nails, etc.

Perhaps most importantly here, how much consideration was given to the drawn-in interior walls when designing a cost-pressured prefab house?

 

[Gulldus]

Yes, and what do you want to say with that?
I have never claimed that it is not possible to construct free-standing roof trusses. Of course, it is.
I have built such myself in the snow zone of southern Lapland with similar spans as the house in question here.

if you read once more what you write and what I answer, you'll probably understand

 

[GoC]

The most important thing here might be, how much consideration was given to the drawn interior walls when designing a price-driven prefab house?

Since the ceiling was to be installed BEFORE the interior walls, you can figure that out for yourself. And how do you know that the house was price-driven? Of course, that's no reason not to dimension the roof trusses correctly.

 

[MultiMan]

Since the ceiling was supposed to be installed BEFORE the interior walls, you can figure it out yourself. And how do you know the house was cost-cutting? There's certainly no basis for not sizing the roof trusses correctly.

Maybe this post makes one think that way? https://www.byggahus.se/forum/threa...tog-ner-innervaegg.558173/page-3#post-6342351

Spent a lot of time in Gullringen during my teenage years in the 1970s when the house factory was in full swing. What was said was the manufacturer Krister Ansgarius was frugal and wanted the smallest possible beam size, and the factory used lightweight beams early on.

 

[Huddingebo]

if you read once more what you write and what I respond, you'll probably get it

It's rather you who refuse to understand what I mean.
That is, just because a truss looks like a certain model of free-spanning truss, it doesn't mean it's designed to fully function as one.
You need to calculate it and study how it is assembled to be sure.

 

[GoC]

It was indeed the case that these houses were built by constructing the ground floor with bricks and fixing the vault. After that, the outer walls were erected, and roof trusses and outer roof were installed. This provided a weather shell where all the interior of the house could be built up at leisure, regardless of weather conditions. So, a pretty smart solution for cost-effective construction. This, of course, required free-standing roof trusses...

 

[Munkfors]

What is meant by "correct camber" when nailing trusses as indicated on the drawing?