Assessment of (partially) renovated house from 1961

[*
Solid duplex from the year 1961
[*]108 sqm living space on ground floor, upper floor and attic (converted)
[*]Fully basemented
[*]Mini balcony on the back side
[*]Energy
[LIST]
[*]A warm-air tiled stove heating system is installed, which was deliberately (?) left in place when moving in, the burner is apparently relatively new
[*]Consumption probably about 1,000 liters of oil per year
[*]Hot water runs on electricity
[*]No high utility costs according to the owner

[*]Electricity completely renewed
[*]Guest WC new, bathroom still needs work (we would probably do this when moving in)
[*]Walls inside completely plastered
[*]Terrace new
[*]Parquet throughout the house
[*]Attic converted, roof insulated from the inside, new attic windows
[*]Windows double or triple glazed, age unclear
[*]Front door renewed
[*]Facade was “done” 15 years ago, completely plastered (still unclear whether the facade was also insulated back then)
[*]Otherwise no known defects
[*]Owners are not aware of any substances still installed anywhere

[*]Heating: I know the pros and cons of a warm air heating system, and the disadvantages are not a deal-breaker for us. It is clear that the heating would need to be replaced in the next few years. After some research I thought of an air-to-air heat pump; with this, the existing system could be replaced with relatively little effort. There is currently funding for this. Or something else? Do I also have to think about ventilation for this? What do I do about hot water? Still use electricity? I would roughly estimate total costs here at around 20-25k€.
[*]Further renovation needs: What else should we keep an eye on or look at more closely during the viewing? New roof covering? Possibly new facade insulation if this has not yet been done? Basement ceiling insulation? I don’t know if the water and sewage pipes were renewed back then, which would also be a major cost factor. If only the water pipes need to be replaced, I would estimate 10k€ here.
[*]Hazardous materials: Where could hazardous materials still be hidden? Asbestos was also used in roof tiles or heating/ventilation pipes.
[*]Other: The viewing is still pending, so I cannot assess, for example, if the basement is damp. Since this is a “partially renovated” property and some things have already been renewed, I would also be interested in any hints about further potentially costly renovation needs or areas to be checked on the house.

I would assume a complete renovation where only the shell without the roof remains.

Basically, you should carry out the inspection with an architect experienced in old buildings - from personal experience - as part of a property purchase consultation. After the property inspection, he will be able to give you an assessment of the points you inquired about in a follow-up discussion.

A scout ID illuminates crystal balls. A semi-detached house from 1961 will mean a single-shell party wall. Whether the facade is insulated can be seen, as well as the number of panes (lighter test, but double glazing does not have to be worse).

Basically, you should conduct the inspection with an architect experienced in old buildings - from personal practice - as part of a real estate purchase consultation. After the property walkthrough, they will be able to provide an assessment in a follow-up discussion on the points you requested.

The following must be checked;
- legal building compliance of the offered property in all parts - the most important inspection. There are often surprises here that also affect the real estate agent/owner.
- Assessment of the condition of preservation
- Quality and energy efficiency of the building fabric
- Possible building damage/moisture damage
- The need for renovation and modernization
- Shell construction/roof structure/statics for any planned conversion and expansion options
- The structural and building physics coherence of already executed renovation work
- The building and planning law situation for expansion, change of use and extension projects
- Numerous documents for freedom from encumbrances (land register/building encumbrances/development costs, etc.)

From experience, the converted attic is critical, as it is usually used without a building permit. Also, all self-performed renovation measures mostly do not comply with the current state of the art and are often questionable in terms of building physics.

In your position, I would assume a core renovation, where only the shell without the roof remains. The rest of the building structure must be rebuilt new and according to current standards and your requirements, including floor plan changes, energy-efficient renovation (building insulation/heating/windows) and new building services (electrical/heating/plumbing/ventilation/cooling). Pollutants and disposal costs will naturally also play a role.

The renovation planning should also preferably be developed by an architect as a concept for the entire building. Renovation with makeshift offers from independently acting and arbitrarily working construction companies, each of which can only oversee their own trade - in the best case - is not useful.

That is always advisable. Do not forget to “tap” the owners of the neighboring half about what they have already done/had to do and how their experiences were. This also applies generally to those readers dealing with terraced houses. When a house has siblings, this usually also helps in completing the building files. Get as many of these documents as possible in advance, so the expert conducting the walkthrough can look behind the scenes more deliberately. Do not skimp on the qualification of this companion; a new build architect or a craftsman who merely does some construction-related work are rather weak aids.