Construction costs for terraces, etc. in cost estimation according to DIN 27

Depends on how close an architect is to the construction, or if they just spend all day painting beautiful & expensive pictures.

Thank you for your initial comments on this. I would like to explain a little more about what we are concerned with.

We are basically now facing the two concepts:
- No. 1 without any roof overhang or terraces with 200 sqm living space, which exactly meets our budget according to the cost estimate.
- No. 2 with 180 sqm living space and on the south side I can step out upstairs onto a terrace that is a total of 40 sqm, which at the same time serves as structural sun protection for the ground floor. In addition, the terrace upstairs is also covered by a corresponding roof overhang and thus has structural sun protection.

Now the problem: No. 2 costs significantly more according to the cost estimate than No. 1, because basically 40 sqm and the volume between the terrace and the roof overhang are included 1:1 in the key figures.

Even though the costs obviously do not fall to 1/10 for this volume or terrace size, logically it cannot cost 1:1 as much as fully enclosed space???

It depends on how closely an architect is involved with the construction, or if they just spend the whole day painting beautiful & expensive pictures.

But that should be figured out...

No. 2 180 sqm living area and on the south side I can step out on the upper floor onto a terrace of a total 40 sqm, which at the same time serves as a structural sunshade for the ground floor. In addition, the terrace on the upper floor is also covered by a corresponding roof overhang and thus has a structural sunshade

Detach yourself from the estimate and the idea that you can somehow convert your design 1 into design 2. Approach it differently... so I understand you correctly (you can't even post a hand sketch?):

- You have a building with 180 sqm area. Additionally 40 (!!) sqm terrace. As a cantilever. So not ground floor 110 upper floor 70 sqm which results in the terrace, but the terrace is a complete cantilever? And this cantilever is additionally covered on the entire surface??? Excuse me if I say it like this... but you shouldn’t be surprised if the costs explode...

...maybe I am just too stupid to understand the "structural sunshade" for the ground floor

Why shouldn't an excavation be more expensive? Walls and windows are also there, but what such a cantilever needs is structural engineering.

And let me guess: the giant terrace is supposed to do without support posts?

No. 1 without any roof overhang or terraces with 200 sqm of living space, which exactly fits our budget according to the cost estimate.

This has already been mentioned here. The cost estimate comes with a +/- 30% accuracy, or it should at most (otherwise you’ll see each other later in court). In today’s times, as a builder, I would consider the +30% as set. Ergo: If your budget just barely covers the cost estimate, it’s time to pull the emergency brake.

And just out of interest: Did I understand correctly that you basically want to build a 40 sqm roof terrace? That would be 40 sqm of covered terrace on the ground floor and 40 sqm of covered roof terrace. So he calculates 80 sqm of covered terrace and converts 1/4 of their area 1:1 into costs – that doesn’t seem exaggerated to me and incidentally also corresponds to the living space ordinance, which counts terraces with 1/4 to 1/2 of their area.