If applicable, house construction, your opinion

Hello everyone,

we are considering whether we should buy a single-family house.

For a few days now, we have shortlisted a very nice house.

Here are a few facts:

Detached single-family house built in 1974, living area 120 sqm + 35 sqm granny flat (separately accessible) (added later, built in 1995) fully basement + underground garage. Plot approx. 770 sqm. Pool 8 x 4 meters (depth 1.80)

The house was occupied by an elderly couple. The husband has passed away, so the wife no longer wants or can live in the house alone.

According to the appraisal, the following work still needs to be done:
Plastering small cracks outside and repainting
Pool (not in use for 4 years) to be refurbished with liner (or similar).

We would also consider the following work reasonable:
- complete package installation
- removing wallpaper and filling, painting
- 2 completely new bathrooms
- removing one drywall partition
- installing a main beam so that another wall can be partially removed
- integrating the granny flat into the house
- redesigning or raising the terrace

So now finally my questions:
- Is the following heating sufficient? Natural gas boiler, Viessmann Atola 24 kW indirect water heater, Viessmann Rudo Cell coated 160 liter panel radiators
- Exterior walls made of aerated concrete 24 cm is that okay? Basement walls with 36.5 brick masonry
- Partition walls are also made of aerated concrete / brick masonry
- Electrical system: copper wiring. Good or bad?
- In the granny flat there is a shed roof, wooden rafters, insulation and bitumen membrane, okay?
- The granny flat was added later. The former exterior wall was not used as a connecting wall, but a drywall partition (with an air gap between the "old" exterior wall and the drywall) was newly built (understandable?). Is that good or bad? We want to make a breakthrough through the former exterior wall to also use the granny flat...

Sorry for the many questions. But many things are running through our minds.

Thanks for the help
Best regards
Caro

a) A pool costs a lot of money to maintain when it is in operation b) 24kw for "only" 155m² I find almost oversized c) 24cm concrete walls without any insulation I find not great in terms of energy demand, what does the energy certificate say?? D) Copper pipes I am not sure about, how old is the electrical system in the whole house then? E) Pitched roof with insulation does not sound bad F) I can't quite visualize the thing with the outer and inner wall G) It should be considered whether a 35m² apartment is still rentable today, after all you must have already included the income in your financial plan, right? H) It needs to be clarified where the cracks in the plaster come from, is it new textured plaster in a strong color tone that becomes slightly cracked due to sun exposure, or still properly old plaster, then it has to be clarified how it looks behind it, whether the masonry also shows cracks

So finally my questions:

- Is the following heating system sufficient? Natural gas boiler, Viessmann Atola 24 kW indirect hot water tank, Viessmann Rudo Cell coated 160 liter panel radiators

The most important thing in this matter would be what technology this device can offer and what year of manufacture it is.
The 24 kW are already fine.

- Exterior walls made of aerated concrete 24 cm, is that okay?

Personally, I don't think much of these bricks, they have too many disadvantages for me.

[*] due to low density, only low sound insulation compared to other solid building materials
[*] due to porosity, risk of building damage from moisture absorption, not suitable as an exterior wall without further coating measures
[*] in case of penetrating water, unfavorable building physics behavior compared to other solid building materials (releases moisture only reluctantly)
[*] low point load capacity, problems e.g. when anchoring heavy elements

What would certainly be an advantage is to restore the exterior facade and glue Styrofoam panels.

- Basement walls are made of 36.5 clay bricks

Unfortunately, that doesn't say anything; the important aspect is the insulation of the floor slab as well as exterior walls in the soil.

- Partition walls are also made of aerated concrete / clay bricks

I see no problem there.

- Electricity: copper wiring. Good or bad?

Well, I would say, what does the electrical box look like regarding fuses etc., main connection etc., has an inspection already been carried out?

- In the granny flat, there is a shed roof, wooden rafters, insulation and bitumen felt, okay?

Sounds good, but the most important thing would be what kind of insulation was used and what thickness was applied.

- The granny flat was added later. The former exterior wall was not used as a connecting wall, but a drywall partition wall (with an air gap between the "old" exterior wall and the drywall partition) was newly built (understandable?) Is that good or bad?

It may be because it was deliberately set up separately for sound insulation and because they are two separate houses, i.e., not connected to each other.

We want to make an opening through the former exterior wall in order to also use the granny flat...

I see no problem with that.

Well, that was my two cents and the first impression.
Best regards ;)