2-family house: Border construction adjacent to neighbor's house about 70% more expensive!

Hello,
I am a silent reader but now have to turn to the experts here in the forum.
We already have the plot, but it must be freed from a barn with asbestos.

Our first specification for a 2-family prefabricated house in timber frame construction stated the following:
- 215 sqm living space, ground floor + upper floor, no developed attic (12.46 x 9.33 m)
- €330,000

Now the shock: the new specification is a whopping €540,000!
- Semi-detached house 260 sqm ground floor + upper floor with developed attic (10.56 / 11.21 m)
- Boundary construction on existing neighboring building. I believe we have to comply with the neighbor’s house regarding height, width, and roof pitch? Right?
- Roof pitch 33° + half-hipped roof
- No earthworks, soil report said approx. 80 cm
- Staircase extension, two stories with flat roof 2.29 x 6.83
- 5 roof windows
- No interior doors + frames, no plastered walls and ceilings, no floor coverings
- Air-water heat pump for 260 sqm with underfloor heating
- Each floor with bath and shower

Otherwise small changes we wanted:
2x tiled shower, reinforcements on the exterior walls, etc...
The sampling is still pending...

I do not know much about electricity and what is important here. But I can definitely say that 2 sockets in the living room are too few :eek:

Question 1: Is the price justified?
Question 2: According to my calculation, we would be at €2000 per sqm. How can we reduce this effectively?
We also have floor plans. But I am not sure if I am allowed to upload them since they were made by an architect. Sorry :(

We simply cannot afford this as there are still so many more costs coming on top of these €540,000 alone.
Until a few days ago, I still felt good with my saved €100,000...

Forgive me, I have surely forgotten to mention many pieces of information...

Greetings and thanks :)

Well, but in the 2nd description you already increased the living space per se and then added a finished attic? Was the stairwell already included in the first description?

Built-up: are both descriptions from the same provider or from two different ones?

Simply the living space alone is sufficient to justify the additional cost.

As already mentioned, you quickly planned an additional 50m², which already costs the first €100,000. In addition, a whole floor, which is more expensive regarding supply lines than simply expanding in width. At least one additional bathroom will be added (€10,000), etc. It adds up quickly. Furthermore, I am not sure whether I would realize a 2.5-story attached semi-detached house in timber frame construction.

The €2000/m² is certainly not cheap, but due to the "connection" to the other semi-detached house, the demolition (including asbestos disposal), the 3 floors, etc., there are certainly substantial cost drivers that can easily demand a 10-20% surcharge.
However, I am already surprised that no earthworks, no plastering, no doors, and no floors are included in this price.

What are the 260m² needed for?

Was the staircase already included in the first description?
No, it actually wasn’t, I never would have thought you could leave that much money there...

Built upon: are both descriptions from the same provider or from two different ones?
Yes, the same provider.

As already mentioned, you quickly planned 50m² more, which already costs the first 100,000€. Additionally, a complete floor, which is more expensive regarding supply lines than simply expanding sideways. At least one additional bathroom will be added (10,000€), etc. That adds up quickly. Also, I’m not sure if I would realize a 2.5-story attached semi-detached house in timber frame construction.

Ok, that explains a lot of the costs, I never would have thought...
Could you maybe briefly explain why you wouldn’t build an extension?
My argument would be that the plot is "free." Only the demolition has to be paid. (Inheritance)

The 2000€/m² certainly isn’t cheap, but due to the "tinkering" to the other semi-detached house, the demolition (including asbestos disposal), the 3 floors, etc., there are definitely substantial cost drivers that quickly demand an extra 10–20% surcharge.
I am, however, surprised that no groundwork, no plastering, no doors and floors are included in that price.

The demolition and asbestos disposal are not included. We have to cover those ourselves.

What are the 260m² needed for?

Ideally, I would like 120sqm-130sqm for the upper floor + attic.
The parents-in-law, who want to move in downstairs, need at least 100sqm. That’s why the technical room is integrated into the staircase extension. So we have about 100 sqm on the upper floor and the rest in the attic.
We probably also can’t vary the house height because we have to build onto the neighbor.

Findings:
-Move staircase inward + technical room (complete extension with flat roof is off the table)
-Make the house narrower (less sqm)
-Give up on the half-hipped roof????

We have scheduled an appointment with our contact person for next week.
-Are there things I can mention so that the house becomes even cheaper?
Or do you think it makes more sense to sell the plot and look for another plot and company? ((200€ per sqm) (nice area with 700 sqm garden)
It would really be nice to build there, but the disadvantages are soon outweighing...

How about much smaller and possibly building without parents-in-law? ;-)

Go through position by position where the cost drivers were. Presumably, there won't be two or three points at €70k each, but rather a lot of small expenses.

Apart from that, I would at least get two or three comparison offers that really have a comparable layout and equipment.