Procedure: Renovate old house + extend

Hello everyone,

I would like to gather opinions on how to best proceed in the following situation:

A house with land is for sale. Since the house is in a desirable location and houses in our city usually sell quickly anyway, it is to be expected that this house will also be sold very quickly.
About the house: 99 m2 living space, year of construction: 1945, basement, ground floor, upper floor, private sale.
Since we want at least 130 m2, an extension to the existing house would be necessary. The existing house probably needs to be completely renovated. We don’t like the layout of the rooms either and it also needs to be changed.
The city’s statement regarding the extension was that, according to the development plan, it is actually not allowed. But if it is, as we have stated, about a 40 m2 extension, there should actually be no problems with the approval.
An appointment for viewing with the owners is arranged.
The house could be paid for with the equity available.

How can I clarify my questions as quickly as possible, ideally already at the first viewing?
How do I find out approximately what costs would be incurred for the expansion and renovation?
We could spend about 250,000 euros on renovation + expansion. Would that be enough?

Since the location is good for us and the size of the land is also optimal, we are already very interested in this house.

So how do I best proceed? Bring a building surveyor to the first appointment right away, or an architect, or both? Can a building surveyor tell me whether an extension is basically possible and which walls in the old house can be torn down? Or who can tell me that? If the result is positive, should I say right away that I want to buy the house?
Or first go to the appointment alone and then possibly arrange a second appointment and bring a building surveyor or architect then? But then I risk that the house is already sold.

Your suggestions?
Thank you.

At first glance, I would also say that if you don’t particularly like the existing structure anyway, completely tearing it down and then rebuilding is probably easier and cheaper. Actually, you are interested in the plot of land in this location. An extension is technically always possible, but with such a wishy-washy statement "there shouldn’t really be any problems with 40m²," you are not helped – and what if the building authority does obstruct it? Then you are stuck and end up with a great plot of land with a too small, old wreck of a building...

Thanks in advance for your answers.
It is probably really better to have the old house demolished.
From what I've read, it is better to have the basement demolished as well. Reusing it often is not possible and usually involves increased effort and can also cause difficulties.
Since a demolition easily costs around 20,000 euros, we would have about 230,000 euros left for a new house. That gets pretty tight.
If you can or want to use only the plot, the offered plot with house is already very expensive.

Good morning,

unfortunately, I cannot tell from the phone where you come from; therefore, I also do not know if your capital will be sufficient for demolition and new construction. However, regardless of that, a building plot is always worth as much as a buyer is willing to pay for it!

You should speak with your house bank, an independent financing broker, and an insurance company. Only with knowledge of all options, including side issues, can you make a sustainable decision.

Rheinische Grüße

Rheinische Grüße von unterwegs
Bauexperte

Good morning,

unfortunately, I cannot see on the phone where you come from; therefore, I do not know if your capital will be sufficient for demolition and new construction. However, regardless of that, a building plot is always worth as much as a buyer is willing to pay for it!

You should speak with your house bank, an independent financing broker, and an insurance company. Only when you are aware of all options, including side issues, can you make a sustainable decision.

Rhenish greetings from the road
Building expert

Thank you for the response.
Place of residence or construction site is Northern Bavaria.