Cost estimate renovation (purchase decision)

Hello everyone,

we want to buy a large single-family house and convert it for 2 families, the following needs to be done:

- Breakthrough of exterior wall, additional exterior door with stairs (about 1m high)
- various interior walls (drywall, with help from family)
- ceiling breakthrough and new internal staircase between ground floor and upper floor
- simple, inexpensive interior doors (we would trust ourselves to do these)
- division of electrical and water systems for separate billing based on consumption
- breakthrough exterior wall and install terrace door
- renovate 2 bathrooms
- build 2 additional guest WCs

For the planning and application we would hire a structural engineer.

My questions:
Can someone estimate the costs? Is it feasible with 60,000 Euros? It doesn’t have to be luxury standard.
Is a structural engineer better suited than an architect for the planning?
Would a structural engineer be able to estimate the costs by looking at our plans and what fees can he charge for that? Our purchase decision depends on the feasibility of the conversion, but we don’t want to spend too much money on these consulting services, as we have already wasted money on this with another house.

Thanks in advance!

I see a lot of statics-relevant things.

Also 2 bathrooms; and also 2 guest WCs on top.

So 60K I find ambitious. But there is too little information available.

Which federal state?

What about the heating? A central one, or possibly a new one? Sounds ambitious at first, but with a lot of personal effort – we know... But indeed still too little information.

Best regards

60k is illusory. I see 200k upwards.

I see 2 bathrooms already costing around 25-30k€ if they are properly equipped and the work is carried out by a company with a regular invoice, of course including the tiling work.