Old building renovation, underfloor heating, electricity, water, possible pitfalls, etc.

Hello everyone,
after years of reading along, the time has finally come, I am going to renovate.
It concerns a two-family house in the Ostallgäu (Bavaria) with quite a backlog of renovations, moreover, the parents still live on the ground floor or will move there.
The building year is early 60s and it has been repeatedly rebuilt and renovated over the years, nevertheless I probably have to do a lot of new work, partly because it is necessary, partly because I just want to.
Water, electricity, heating, floors, quite a few windows and various other things.
I already have an appointment with a heating and sanitary specialist, as well as regarding the electrics.
Well, since I like to be prepared, I wanted to ask a few questions here:
I would start on the upper floor. I wanted to renew all cables and pipes etc. and switch to underfloor heating.
The limitations for the ground floor would then be limited to breakthroughs for new pipes and lines, at least I hope so. Is that feasible?

I would like to replace the gravel filling in the crawl space with a bonded fill and then have a level floor structure with underfloor heating, currently there are still old radiators installed, heated with oil, firewood and solar, can the heating specialist manage that or should I rather continue to rely on radiators? Additionally, I would then like to lay pipes for a future controlled residential ventilation system on the ground floor.

I am also grateful for suggestions on what I need to pay particular attention to, what I must avoid, and what might be sensible additional investments and alternatives.

I am aware that many questions will arise during the planning and preparation process and I hope I may ask them here.

Thank you very much.

Also for suggestions on what I should particularly pay attention to

Bring an energy consultant on board. Come up with a good plan for what should be done when, where, and how. "Problems" always arise during renovations (I had a similar situation – for example, the electrician simply chased the hot water pipe through the inhabited upper floor. In 1967, the pipe was laid on the wall at that spot and just plastered over :eek: ).
If you are doing a complete renovation, prepare everything directly for the future.

The restrictions for the ground floor would then be limited to breakthroughs for new pipes and cables, I hope at least. Is that feasible?

Then please also replace the pipes at these points for the ground floor at the same time. For example, there are probably risers (water) each with a branch in the ground floor apartment. If you only renew from the ceiling, you will make twice the mess if the ground floor pipe sections also have to be replaced later.

Thank you, the energy consultant will also be added to the list.

As for the lines, I wanted to keep it in the style of a supply shaft anyway.

I would start on the upper floor. I wanted to renew all cables and pipes, etc., and convert to underfloor heating.

But the technical room is usually not on the upper floor. So even if the upper floor is to be the first construction phase, you have to plan holistically.

I would like to replace the gravel fill in the hollow floor with a bound fill and then have a flat floor structure with underfloor heating,

That sounds like a beam ceiling (?)

also, the parents still live on the lower floor or will move there.

Shouldn’t you take the construction phase that is to be completed first as the first phase, especially if seniors are involved?

I am aware that many questions will arise during the planning and preparation, and I hope I may ask them here.

Gladly, however, a forum does not fully replace a (interior) architect. It’s best to get the plans from back then (possibly from the building file) so that one can proceed conceptually. And plenty of pictures of the current state and of the ideas won’t hurt.

We are currently measuring the house and the order is also influenced by the older generation... stubbornness that comes with age.

We are currently measuring the house, and the order is also influenced by the older generation... stubbornness due to age, basically.

Maybe first the important captain question on the boat needs to be clarified.... ;)