Floor plan optimization terraced house 160 sqm, approx. 145 NWF

The ceiling will just be thick enough for the structural stability. And it was made once for dozens of terraced houses, thus virtually free for each additional unit. The execution plans for almost every trade would have to be changed only for this one unit. What you can save in price through standardization for the terraced houses is thus largely canceled out.

And whether the surcharge is justified doesn’t matter to you, because you have only exactly this one provider for it and have already signed. The motto is therefore: take it or leave it. Hence the question: Is it worth the surcharge for you?

I have to put that into perspective a bit. A 20 cm concrete ceiling is planned and above that a 28 cm area (including flooring) for underfloor heating, etc. I thought that supply/exhaust air could fit in there, but I don’t know for sure.

The terraced house is a single object. It has not been built like this before and will not be built again. As wrote, it’s a "batch" of 15 units, of which 3 are in terraced house form. Each floor plan is different. That’s why these immense changes were possible. In principle, no wall (except the exterior walls) has remained the same.

That leads to the point "take it or leave it." As of now, the surcharge is NOT worth it TO ME, but I also assume that this is not the final word. However, if you now say "you have to reckon with at least €15k," then it’s not worth making a fuss. But if the assessment is that there is easily €10k fantasy margin in there, then I am quite sure that he would install it for me with a €5k margin as well.

Every floor plan is different. Therefore, these immense changes were also possible. In principle, no wall (except the exterior walls) has remained the same.

All the more important is for the developer not to invite outliers in the system dimension as well.

But if you now say "you have to reckon with at least €15k", then it's not worth opening a can of worms. But if the assessment is that there is easily €10k of fantasy margin in there,

I think that more than double the profit margin of a retrofitter is not included there. So you are paying a convenience surcharge for an integrated solution instead of a hacked one, and a recognition fee for the avoided mess of retrofitting.

not to also invite outliers in the system dimension.

That worked. We have now, with a heavy heart, decided against a controlled residential ventilation system. The quoted price was no longer 17k € but 21k €. That is now too much of a good thing and we would also have had to find additional space for it. Today we had our first real planning meeting with all involved parties. Of course, planning continued cheerfully based on unfinished plans. Actually, all parties seem quite competent and solution-oriented, only the person coordinating is unfortunately out of place. The result is: planning is stopped again for now and open issues should be clarified as soon as possible. The biggest issue is basically the bathroom layout for the TGA. I still owe you feedback regarding the statics of your design. The solution from the structural engineer is to make the ceiling in the living/kitchen area 2 cm thicker. No more and no less.