Cost for house, external dimensions approximately 7x8 m, 2 full floors

Well, you apparently have to pay not only for the new construction but also for the demolition of an old building, if I understood correctly? If, for example, neighboring buildings also have to be undermined, that can (at least in my imagination) be a cost driver that many others simply don't have. Ultimately, you will only be able to check through various offers and comparisons whether it could also be cheaper. Since you obviously lack the time, in my opinion, you won't get around [Leistungsphase 1-8] (or a "prefabricated house" with everything from a single source) – if only because you won't want to coordinate the scheduling in individual trade contracts...

What I still can’t figure out:

[*]If the €325,000 are the eligible costs and
[*]If they are correctly stated as net and
[*]If we assume that the total costs are 50% above the eligible costs,

then our small semi-detached house with its good 100 sqm costs well over €500,000. That’s all absurd...

exactly that is the crux of the matter. I wouldn’t worry about the architect’s fee for now. The problem is that your house will cost €400,000 plus X, but you only want/can invest €300,000 all inclusive. You should discuss that, and we can’t make any statements here as long as more info is not available (floor plan, development plan, hillside location, etc.).

Basically, you’ve already realized that you miscalculated a bit. Demolition also costs money, which you don’t have with a “normal” new build. But you still have to do the soil replacement because that was not state of the art back then. Since the previous basement was lower, you will probably have to excavate deeper and then of course shore up the other half of the semi-detached house. That all costs money. The small footprint also results in more exterior walls, which tends to be more expensive, and possibly the connection to the other semi-detached house is complicated to realize or maybe forces the architect to make compromises in your build that cost extra. So it doesn’t necessarily mean that the cost estimate is totally off. It also doesn’t help you if it’s calculated very tightly now and you get burned later.

If costs remain this high, I would consider selling the plot again. After all, you bought a house on it, the value of which you are now practically scrapping. If it’s not a very exclusive plot, you are basically building there with gilded stones.
- Demolition
- Extension to a semi-detached house
- narrow building window (height and width)
For that money, you could probably realize 150-170 sqm on a “more generous” plot.

The house is actually an unkempt 80-year-old semi-detached house. According to the building authority, we are not allowed to extend to the front or to the back (to the front because of symmetry, to the back because of the actual building boundary of the street); so only one side remains.

So we are talking about a replacement building here, significantly "limited" by the dimensions of the existing building, which also still has to be demolished?

Then I agree with the assessment that the overall cost will probably be even higher. If the adjustment goes further, for example, if the roofline of the partner building also has to be followed, that will also have an impact on the fee assessment.

The property has already been purchased???

Demolition: get multiple quotes. Talk to the companies yourselves. With us, the difference between the cheapest and the most expensive offer was 80,000 euros. Some wanted to set up shredding plants, others said it was unprofitable for such small quantities, etc. Flat rate for debris or according to the weighing slip. Flat rate for the disposal fee or actually according to an expert report. With or without gutting. For you, the support of the semi-detached house is added.

You have to find out why, how, and what for, and if it is after 10 p.m. The architect stops after 2 or 3 offers. We looked for the demolition for over a year. Get an expert involved. With us, the architect, the geologist, and the structural engineer got really worked up. Foundation underpinning (which applies to you too). I was about to throw them all out. The civil engineer (basement builder) and the expert first brought calm and reason there.

Whether a house can be renovated or is ready for demolition should actually be determined before the purchase. Renovatable is more expensive than demolition-ready.

So many things where I told myself no, I'm not doing that now, it's stuck there. Sometimes just minor things. No one can read thoughts, not even the architect.

It is the biggest private investment you will ever make. How much time is spent planning a vacation or buying a car that costs only a fraction?

Whether a house is renovatable or ready for demolition must actually be determined before the purchase. Renovatable is more expensive than ready for demolition.

It should be that way – in reality, potential land buyers often calculate a plot with a building ready for demolition as if the building were merely worthless. In fact, it is even less than that, and the demolition costs with all the extras must be offset against the land value.