ᐅ Renovating a 1960s House: Questionable Expert Recommendations?

Hello everyone,

I have been following this forum for a while and have now registered due to a current situation. I would appreciate your assessment.

My partner and I are both in our mid-30s, have a young son (15 months old), and are planning to buy a detached single-family house in Middle Franconia (800m² (8600 sq ft) plot without slope, house built in 1959, approximately 123m² (1324 sq ft) of living space) for 360,000 EUR including purchase-related costs. Yesterday, I visited the property with an expert and subsequently committed to the real estate agent. The house has been reserved for us, and we will be able to purchase it.

My partner (a civil servant teacher) is absolutely convinced about managing construction projects. I am an engineer specializing in energy-saving measures, but professionally I mostly work with large ventilation systems, combined heat and power plants, and boiler systems in the triple-digit kilowatt range, with almost no experience in insulation. However, I do have some technical knowledge and experience estimating costs.

Here are the key facts in brief, from bottom to top:

• Basement: boiler room + oil storage, workshop, storage/pantry, laundry room with external stairs leading to the garden.
• Ground floor: entrance hall, toilet, small bathroom with bathtub, living room with a wood stove and patio door (garden access), dining room, kitchen.
• Upper floor: bathroom (also with wooden floor and carpet on top), 3 bedrooms.
• Attic, accessible via folding stairs: two small, identical rooms. I estimate about 6m² (65 sq ft) each; this area was not included in the stated living space (123m²). Above these rooms is about 0.8m (2.6 ft) of space up to the ridge.

Current condition:

• A leak in the workshop: the electrical line entry point is leaking. During heavy rain, about 2 buckets of water enter.
• Some basement ceilings are covered with old-looking insulation, which appears to be a thin, homemade foam polystyrene layer.
• Heating: oil heating system, installed in 1999. Gas connection is also available in the house.
• Electrical wiring is two-wire.
• Floors are wooden planks everywhere. Most rooms have carpets laid on top.
• Exterior walls according to the floor plan are 30cm (12 inches) brick with plaster on top.
• The gable roof was re-covered around 1980 (clay tiles) and has mineral wood fiber insulation between rafters. On the room side there is a "straw mat plaster" and wood paneling. No irregularities are visible from outside; the tiles are just a bit mossy. From inside, you can look directly under the ridge and see the beams with no signs of moisture or similar issues.

Before the expert assessment, we thought this would be a major renovation and planned to start from scratch.
In other words: remove all wiring (water, electricity, heating) and install new ones, insulate the facade, insulate the roof, install new triple-glazed windows. Also, all bathrooms/toilets and the kitchen would be fully renewed. We estimated the total cost for these measures to be a maximum of 240,000 EUR. Friends of ours who completely renovated a similar property three years ago rounded our estimate up to 300,000 EUR and carried out a full renovation with government subsidies and grants.

Now the findings and the expert’s opinion from yesterday:
In advance: I arranged this expert through an online platform and the process had to be quite quick. I spoke with him on the phone beforehand to outline the planned renovation scope and was curious who would show up. He is around 70 years old and, according to his business card, a certified building damage expert. He also does mold assessments and quality control during construction. He seems to be a "never change a running system" type. I trust his assessment of the building’s condition, but on some topics he seemed less knowledgeable (for example, he said that the efficiency of a condensing boiler and return temperature/temperature level have nothing to do with each other. Also, he claimed there is no legal insulation requirement).

• He measured wall moisture in almost every room. Considering the house has been unoccupied and unventilated for two years, the values are good. Of course, there was more moisture in the workshop. He would fix the leak as follows: dig around the corner of the house where the damage is, about 2m (6.5 ft) in radius down to the basement floor level. Disconnect and pull back the electrical cable, drill a new hole, and seal it properly. He estimates the cost at around 5,000 EUR.
• Surprisingly, he would also install small radiators in the basement rooms to maintain basic heating and thus prevent mold. He said the heat isn’t lost but rises, though to me adding radiators in the basement seemed odd.
• Regarding the heating system, he recommends replacing the oil boiler with a gas condensing boiler, which would bring significant savings. I find that questionable, especially if the system runs at 70/50°C and nobody wonders why it doesn’t condense.
• For the exterior walls (minor plaster cracks mainly on the south side), he would simply apply a second layer of plaster to improve appearance, but would not add insulation. If I understand the local energy regulations correctly, this is permissible without mandatory insulation. Still, I have reservations about just plastering over old plaster and hoping it will hold. Is this common practice?
• As for the roof, he would also leave it as is. However, in my opinion, the energy regulations clearly require insulation of either the top floor ceiling or the roof if the minimum standards of DIN 4108-2 (2013) are not met. The old insulation in the roof likely will not comply.
• When replacing windows, he would not recommend the most airtight options but double glazing with a U-value between 1.3 and 1.5.
• He suggested completely renewing the electrical system and estimated costs of at least 20,000 EUR for this. Heating and water pipes would remain. We strongly doubt this, as we don’t feel comfortable keeping 60-year-old pipes, even if they could last another 20 years. Opening walls and floors in a fully occupied home later would be a nightmare.

In summary, he recommends significantly less renovation than we had planned. He said this could save about 100,000 EUR. Our goal and desire is to prepare a home that does not require ongoing renovation every five years because improvements need to be made bit by bit. However, we do not want a fully insulated, deep-renovated house at any cost either. I understand that he prefers to retain a functioning, mold-free building and only insulate further if absolutely necessary. On the other hand, energy costs over the next 50 years cannot be ignored.

I am interested in your opinions on the points described. I can provide more detailed information if needed. I understand that it is difficult to assess everything from a distance, especially since insulation is a controversial topic. Since I have little experience in this area, I find it hard to properly evaluate his statements.

At the moment, I plan to consult a second expert (Are there secret tips on where to find reliable ones?) and get a second opinion on site.

Maybe someone has read this whole post, has experience with such projects, and/or completely different ideas or objections that I haven’t considered yet.
I look forward to hearing from you and thank you in advance for any feedback.

schwalbe