(Almost) complete renovation of a single-family house from 1968 / what costs will we face?

I have been following various threads here in the forum for some time now and have now registered myself, as after years of searching our purchase and thus renovation project is taking concrete shape.

Year of construction 1968, that is somewhat younger than the extensively described example here from

We now have a specific property in mind and are currently trying to get as realistic a picture as possible of the renovation costs to come.

Then it can be helpful for the discussion to show it in more detail once: photos of the condition, and preferably also floor plans in the synopsis existing/wish for conversion and section.

We want to approach it backwards, get a good idea of the renovation costs, deduct that from 1.1 million and then make a corresponding offer to the seller. If they accept it – good. If not – also okay, we definitely do not want to buy something and then live for years in an unfinished property or overwhelm ourselves completely with a huge loan.

That is a popular but mostly doomed-to-fail idea: as understandable as it is from the buyers’ perspective, the worse it works, precisely because it is thought from the buyers’ perspective only. The sellers, on the other hand, often have their ideas about the residual value of their property somewhat “secured” as well, and feel attacked or that the value of the property is undervalued and prefer to give it to a higher bidder. The likelihood of getting kicked out with this “valuation method” is therefore extremely high. The example I linked above, by the way, is a property already being lived in and modernized and soon to be converted, which seems to work quite well. I fully agree with the last sentence, though.

Year of construction 1968, that is somewhat younger than the example described in detail here by

Thank you very much, I will read into it! At first glance, it looks super detailed, super well documented.

Then it might be helpful for the discussion to show it closer once: photos of the condition, and preferably also floor plans in the synopsis existing state/wish for renovation and section.

We do not want to change anything in the floor plan, it fits exactly as it is – almost a miracle! Nevertheless, I have inserted it for cost estimation regarding electricity and water (I think a floor plan can help here because of the meters of lines needed).

That is a popular but mostly doomed-to-fail idea: as understandable as it is from the buyers' perspective, the worse it works precisely because it is thought one-sidedly from the buyers’ perspective. The sellers, on the other hand, often have their ideas about the residual value of their property somewhat "secured" as well, and feel attacked or that the value of the property is underestimated by this assessment and prefer to give it to a multi-bidder. The likelihood of getting kicked out with this "valuation method" is therefore extremely high.

You are of course right, each side comes from their own perspective and for that you have to have empathy. We would of course communicate the whole thing respectfully, but in the end, it still comes down to this: Either we can afford house + renovation, or not. We don’t want to end up far over budget, no matter how beautiful the house is or how much we like the floor plan :) If our maximum budget is below the sellers’ minimum price, then that’s also okay and we would continue searching.

Your approach can definitely work.
We did exactly the same.

I clearly communicated that I had no interest in opaque negotiations and endless back and forth, that our budget was at X, we would budget renovation costs with an expert at Y, and the maximum price we were willing to pay was therefore Z.
But I also would have actually walked away otherwise and would not have accepted anything more because we didn't have to buy.
It was accepted – maybe now is the right time for that, there aren’t many buyers around. A year ago that probably wouldn’t have worked...

Example: The facade insulation (high-quality material so that the eaves did not have to be extended) with just over 220 sqm (area without windows) should cost the craftsman around €80k.

But that is already very expensive - not taking my project, as we really got external insulation & plaster very cheaply, but as a random example from another project carried out in early 2023: about 340 sqm of area to be worked on, for everything (setup, base rails, ETICS EPS 032 boards, corner protection, sealing tapes, reinforcement, light plaster, primer & top coat) cost about €45,000 gross in the end, or about €132 / sqm all-inclusive (except for scaffolding, as calculated/contracted separately).

Well, it was a new build, so certainly there is still something to add for substrate preparation, and labor costs are certainly higher, but I really can't imagine how you can come up with over €350 / sqm just for insulation.

Okay, it was new construction, so there is certainly something to consider for the ground preparation, and the labor costs are certainly higher, but I can’t quite imagine how you can get to over €350 / sqm just for the insulation.

220 sqm insulation area (+ base insulation) plus 20 windows with reveals. High-quality insulation - not EPS, but phenolic resin insulation WLG 022, which costs about €100/sqm online (the craftsman charges more). However, the high costs for extending the roof overhang were saved. Otherwise, the roofer would have had to work hard on the roof.
Therefore, a significantly more complex project (e.g. window reveals or insulation on clinker facade) or not so cheap materials (insulation boards, special adhesive for phenolic resin and suitable plaster). But now nearly KfW 40 and 40% subsidy.
What you know as an all-in price is not even the material cost for me...

OK, Resol is indeed significantly more expensive, but even so - EPS 032 140 mm usually costs around €18 / sqm, in the same store webertherm RS 021 140 mm costs €90 / sqm. Let it be an €80 / sqm surcharge, you are still way beyond reasonable with €350 / sqm.

I am sure that it made sense for you or was otherwise not possible or more expensive, but cost planning should not necessarily be based on such special cases.