Old building renovation, house built in 1916, multi-family house converted to single-family home, experiences

That sounds more like a higher-quality building, not one for workers or the like. To me, it sounds like a pretty little house. If not much has been done so far, you’ll have to do a full renovation anyway.

Our basement was built as a damp cellar. In those construction years, basements weren’t supposed to be dry because they were used as storage rooms with high humidity. You can dry something like that with a lot of effort or just leave it as is; we decided on the latter for now. At first, we didn’t open our ceilings, but this year in February, just out of curiosity, we opened one room and were rather positively surprised. Everything completely dry, solidly built, with much thicker beams than previously assumed. The building shell had been solidly renovated in the 90s, so we left it as it was; so far, we have replaced almost all the windows, insulated the roof, mostly redone the interior plaster, completely redone plumbing, electricity, and bathrooms, and interior doors. We removed some old contaminants, ugly wooden paneling from the 70s and such. Beautiful wooden stairs were uncovered again. We had no nasty surprises; apparently, our house was always well maintained.

What you’re planning is not a renovation; it’s a renovation/restoration. If you want everything to meet new-build standards, it will be expensive, that’s a forewarning. We never aimed for that. For a house with 100m2 and the mentioned renovations mostly done by ourselves (except plumbing, electricity, and tiles), we have roughly spent 80,000€ so far. Of course, you could have sunk 200,000€, but we didn’t find that necessary at all. We have lived here for 4 years and pay 45€ for gas, 63 for electricity. So our house is certainly not an energy guzzler.

I would like to install a photovoltaic system combined with a heat pump, but I have read that this is not so easy in an old building.

Nonsense, if you are renewing everything anyway. I even achieve KFW 55.

I am basically assuming costs of 250-300k€ for the renovation.

That will be a total luxury property if you have such a budget.

With this budget, there is no need to be afraid of problems^^.

Yes, it will be a renovation, not a refurbishment, that is correct. The house is rather upscale, I believe it was originally built by a pastor. Unfortunately, the house is not around the corner from us, so we have to do everything with an architect who can also be on site. Doing it ourselves will also be less possible than we would like. Demolition and then during construction doing floors and a few helpers. I thought I'd get the cost estimate thrown at me directly ;) we do not intend to turn it into a total luxury villa. We are rather down-to-earth. Feeling comfortable is the most important thing. I have no intention of "alexa" ruling the entire house or anything like that.

The costs are currently difficult to estimate. The house is of course quite large, it needs to be renovated, and you can only do a little yourselves. But with the budget, it will certainly work out. It really depends a lot on what you want. You often read here first "it shouldn't be luxurious," but then more and more things come up that people do want and that drive up the price. Those who want to turn an old building into something like a new building usually end up at the price of a new building (even though a renovation is still more ecological). Those who cannot live with compromises should rather build new. But I would always prefer such a little gem. If it goes in the direction of a parsonage, it is certainly a really nice house.

The question is, what is luxury? I don't need a 30 sqm bathroom, not necessarily underfloor heating everywhere, and no professional kitchen. But the house will need a new roof and the floor plan must be changed in one or another corner. Likewise, the pipes and the electrical system should be redone. And insulation should also be added here and there... that adds up to quite a bit. But I am glad for every euro that it ends up costing less...