Extension of residential house in bungalow style - increase roof pitch?!

I had asked about the possible knee wall raise in another thread – but that will probably not happen. The static structure and substructure there are too risky.

Unfortunately, the same applies to the statics and substructure of a discussion that shouldn’t be posted elsewhere – especially not unlinked. Even with a change of course, it remains the same object we have already discussed here, and you should actually have continued it here:

General opinions without detailed floor plans and calculations would be nice.

... but unfortunately deprived of essential basics. Then one only exhausts oneself in wild speculations without rhyme or reason. I can give you a written guarantee from prisoner social work that burglars never orient themselves by the positions of safes in builder forums; that would be decidedly too inefficient. But as you already touched on with the keyword "statics," without being able to fathom them, unfortunately much would be just useless babble. Gravity is relevant, after all.

The question is whether it would basically be an idea to "rebuild" the roof from the current 30 degrees to 45-55 degrees pitch. [...]
One idea would be to use the long "L-section" as living space and the shorter part rather as a "storage area." Although it would certainly look odd to change only the long part and leave the short part as it is.

Unfortunately, this is a naive layman’s idea that changing the steepness of the roof would be significantly less tricky than the previously considered knee wall insertion. Incidentally, the nature of the hip roof would change little as a result, and without floor plans, everything is basically undiscussable. It would also look very off-putting. I believe I already made you the suggestion to raise only one leg of the L (and also mentioned that economically changing the object would be the more cost-effective way). However, I am no longer sure whether I emphasized: the significantly more cost-effective. Otherwise, I fear that with your remark

It’s a pity that many other forum users either assume a lot of expertise or just toss out one-liners.

you effectively brought the previous discussion to a close.

In the middle of the long L-piece, it is currently about 2.2m high. However, there is currently only insulation laid on the reinforced concrete ceiling and OSB boards on top. If we build a proper floor structure with underfloor heating there, we will lose height again. In total, the usable space will always remain very small.

Previous insulation and floor structure should roughly balance each other out. The thermal envelope is then moved to the roof, and underfloor heating under an intermediate ceiling does not necessarily require 10cm of insulation. 2.20m is indeed not much. But it surprises me a bit, since our house certainly has smaller dimensions and we should get about 2.30m under the ridge purlin.

Even with dormers that we would then build, the usable space is still rather too small. I do not want or expect any detailed calculations, prices, or feasibility studies here. The question is simply whether and to what extent it is fundamentally conceivable. There may well be people who do not sell their house because of this but carry out such conversions. We are fully aware that we have to discuss everything with authorities, structural engineers, architects.

I do not want or expect detailed calculations, prices, or feasibility studies here. The question is simply whether and to what extent it is fundamentally conceivable.

I do not follow why the existing thread fixated on the base slab when looking at the overall picture. Only the doubts about the financial foundation (related to the desired budget) seem valid to me – for both options (adding a storey and initial construction). So in principle, it is feasible in my opinion.

Basically, almost everything is technically feasible. There are also options for the renovation of foundations. But it all costs money. You also mentioned the severely disabled daughter in the other thread. Is the attic really the right place for her or do you want to move upstairs?

Basically, almost everything is technically feasible. There are also options for the renovation of foundations. But it all costs money. You also mention your severely disabled daughter in the other thread. Is the attic really the right place for her, or do you want to move upstairs?

No, our second daughter is supposed to move upstairs, for at least 10 years. Hence the large and expensive effort. Our disabled daughter is supposed to have a completely separate living area downstairs. We do not want to put her in a care home.