Consultation for house purchase from an inheritance community, built in 1967, 230 sqm unrenovated

I once read as a rough guideline that if the renovation costs exceed the purchase price by 75%, a demolition and new build might become interesting. But the same conditions would apply for us as for external buyers, so that really isn't an option either. You would only save money if you additionally divide the land, sell half, and build significantly smaller yourself, right?

I once read as a rough guideline that if the renovation costs exceed 75% of the purchase price, a demolition and new construction could become interesting. But for us, the same conditions would apply as for external buyers, so that is not really an option. You would therefore only save if you divide the plot additionally, sell half, and build significantly smaller yourself, right?

Correction. 75% of the costs for a new build were meant. That is also difficult to assess.

The obligation to renovate when buying primarily includes, as far as I know, the insulation upwards (roof or top floor ceiling), the heating system, and heat-carrying pipes. You write that the roof is uninsulated, but is the ceiling as well? Or is the upper floor open upwards to the roof? The heating system does not need to be renovated due to a low-temperature boiler? Where does this information come from? If the latter is true, in my opinion only the insulation of the roof and heat-carrying pipes remains if the ceiling is not insulated there. That would be a manageable investment. Even if the radiators still had to be replaced, it would still be reasonable. Everything else is initially voluntary, as far as I know. Therefore, the question is rather whether you want to renovate more at all or just buy the house first.

As far as I know, the renovation obligation when buying includes firstly the insulation upwards (roof or top floor ceiling), the heating system, and heat-conducting pipes. You write that the roof is uninsulated, but is the ceiling uninsulated as well? Or is the upper floor open upwards to the roof?

Partly, partly. In the single-story part of the building, the "ceiling = roof", in the two-story part there is an "attic" that is between 30 and 100 cm high. In both cases there is a layer of glass wool from 1967 without a vapor barrier or similar beneath the ceiling. In winter, we have no snow above the heated rooms – so the insulation effect is likely negligible. The area above the glass wool is continuously ventilated through ventilation slots at both ends of the roof, which is why I assume that under-rafter insulation would fail in its effect if the air underneath "blows through," or am I wrong to think that? So it would have to be insulated "from the inside," I assume.

The heating system does not have to be renovated because of a low-temperature boiler? Where does this info come from?

That’s how I read it in the Building Energy Act and the chimney sweep’s inspection report. No replacement obligation for over-30-year-old low-temperature boilers. Whether that makes sense energetically is a different question – since we don't have to replace it, there is the chance of funding. There would be plenty of space for pellets. A heat pump would also be interesting. But according to my understanding, in both cases, especially the latter, a substantial insulation would have to be done beforehand. Basically, it seems logical to me to insulate the house first and then install the appropriate heating, not the other way around.

If the latter is true, in my opinion only the insulation of the roof and heat-conducting pipes remains, if the ceiling is not insulated. That would be a manageable investment. Even if the radiators had to be replaced, that would still be within reason. Everything else is initially voluntary, as far as I know. So the question is rather whether you want to renovate more or first just buy the house.

That would certainly be conceivable, but with the current energy consumption and rising energy costs (currently €700 per month for oil and electricity alone), something has to happen.

But in my understanding, in both cases, especially in the latter, significant insulation would have to be done beforehand. Basically, it seems logical to me to insulate the house first and then install the appropriate heating system, not the other way around.

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That would certainly be conceivable, but with the current energy consumption and rising energy costs (currently it is 700€ monthly just for oil and electricity), something has to happen.

That certainly makes sense and most people do it that way. Add insulation and replace radiators. I just wanted to say that not everything you push forward as an urgent wave of problems is mandatory. You don’t have to go into a million debt right away if it’s not financially feasible yet. Then just do what makes sense for now and leave the electrical and sanitary installations as they are.

Whereas I find that to be wishful thinking. Water pipes can fail quite spontaneously depending on the material, keyword [Kupferfraß]. And other energy-related renovations also cost money, just like not renovating does. The money has to come from somewhere.