Underfloor heating on the ground floor: insulate or not?

Hello,

I have a question:

In my house, there is currently an electric underfloor heating system installed on the ground floor, upper floor, and attic in all rooms. I am planning to install a heat pump and subsequently lay the water pipes by milling into the screed.

According to the building certificate, insulation is already present under the screed. Now I am wondering if it makes sense to completely remove the screed on the ground floor, install new impact sound and thermal insulation, and then lay a new screed. The terraced house was built in 1990.

On the upper floor and attic, I plan to only mill the water pipes into the existing screed. Would you recommend removing the screed on the ground floor as well, or is it sufficient to just mill the pipes there too?

Best regards

If there is no knowledge about the structure of the floor, I would open up the floor in an inconspicuous spot to obtain the necessary information.

If there is no knowledge about the structure of the floor, I would open up the floor at an inconspicuous spot to gain the necessary information from it.

The building certificate already states that a 5 cm thermal and impact sound insulation should be present. I assume it is indeed there because I removed the tiles and you can see the edge insulation on the side.

But would that be sufficient, meaning the insulation?

Structure of the floor

You need to answer Knöpfchen's question very specifically. Name each layer and also the material. For example, Styropor WLG 040 could be replaced with PUR WLG 024.
If there is a 25mm cast asphalt screed, you cannot mill.
Just to mention two examples.

7 cm screed, foil, 5 cm thermal and impact sound insulation

unfortunately, there are no specifications on which exact materials are used, but the screed should be cement screed

7 cm screed, foil, 5 cm thermal impact sound insulation

unfortunately there are no details about the exact materials used, but the screed should be cement screed

Then I would remove the screed, lay PUR insulation and have a screed as thin as possible applied over the underfloor heating pipes. For example, 6cm PUR with aluminum foil, on top a grid foil and tack the underfloor heating pipes. Then 60mm screed (45mm coverage of the pipes) and you reach your 12cm. This way you roughly double the thermal insulation.