Single-family house 140 sqm with basement ready - house price

Hello everyone,

We have been planning our single-family house for some time now and were initially looking for the perfect building plot on the Swabian Alb (BW). About 2 months ago, we finally found it and have identified the perfect hillside plot with a beautiful view and a suitable size of 620 sqm. The plot has a slope of about 16 degrees.

Before purchasing the plot, we inquired with many renowned and high-quality prefabricated house manufacturers and visited some show homes. The offers for turnkey houses of about 135 sqm were between 300k and 370k €.

Due to the hillside location and the desire for the largest possible flat garden, we have now turned to a local developer to also be offered an "architect-designed" house where everything is implemented from a single source: house, basement, and outdoor facilities – turnkey. In addition, we have already gained some experience with this developer, as our single-family house was also built by this developer – so the trust is quite high.

After several planning discussions, we have now arrived at the final design of the single-family house with outdoor facilities:

- Solid house 140.23 m² living space
- Basement 69.14 m² with double garage (room height 2.30 m)
- Enclosed volume 851 m³
- High-standard fittings
- Heat pump with underfloor heating
- Central or decentralized ventilation system
- Electric shutters only on the ground floor
- No smart home

Price:
House 440k €
Earthworks 12k €
Outdoor facilities 40k €
Total = 492k €

Although I was quite aware that, in contrast to an "off-the-shelf" house, an individual solid house would be more expensive, I was still shocked when I saw the price for the house. I think the outdoor facilities at just over 40k € are quite plausible. However, I cannot understand the house price of 440k € when compared to a similar offer for a prefabricated house (turnkey, high standard, with 2.50 m basement and garage in the basement); I come to about an 80k € price difference.

When inquiring with the developer, we were told about the much better interior fittings. However, based on our own experience, these fittings are not really high-end, even with the developer.

Are architect-designed solid houses really that much more expensive?
Are the mentioned prices realistic?

I also have another question:
So far, we have not had a soil survey carried out. The developer states that, based on their experience in the same residential area, there are absolutely no concerns about the slope slipping or hillside water. Therefore, no special structural measures need to be considered. The municipality reports the same.
Is it still advisable to consult an expert?

You have to compare the construction services description to understand the price difference. There you will find the actual features and what is included. I could imagine that the solid construction builder includes some things that the prefabricated house manufacturer lacks. Maybe already a different reinforcement because of the slope. You have not listed incidental building costs for either.

Thank you Haydee for your response.

The construction service descriptions do not differ much in scope.

The basement is 2.50 meters high in the prefabricated house. In contrast, it is only 2.30 meters in the developer's house.

The interior fittings are comparable.

For the heating, an air-to-air heat pump is offered in the prefabricated house. The developer offers an air-to-water heat pump with underfloor heating.

Both are KFW55.

I have already included the incidental construction costs for both houses - approximately €70,000.

You have a five-figure difference just with the heating. The systems are not comparable. The underfloor heating is more expensive to purchase and cheaper to maintain. For a non-Passivhaus no air-to-air heat pump. Compare everything, window is not window, staircase not staircase,

That means, are ancillary construction costs and the basement included in the 440k? What is allocated for the basement? If I assume 70k for the basement, then the offer unfortunately seems realistic to me :-( What about flooring and painting work? If that were also included, then the offer from the prefabricated house builders at Hang in BW would almost seem too cheap to me.