Retrofit underfloor heating, experiences

Good day,

we are buying a house from the year 1998. We are actually enthusiastic about the house. Unfortunately, it lacks underfloor heating. We don't want to do without it. We would like to have underfloor heating in the living room and kitchen (one room approx. 48sqm) and in the bathroom on the 1st floor (approx. 12sqm). Currently, there are tiles in these rooms. Now I have done some research on the internet and have seen 3 interesting methods.

1. Milling technique: breaking out tiles (not a problem, we will probably change the floor covering anyway). Then a "groove" for the pipes is milled into the screed. Finally, a leveling compound must be applied and the floor can be laid. Experiences? 2. Uponor low build-up system. Allegedly, the system can even be glued onto the existing tiles. Overall, it should only be 10-15mm high. Experiences? 3. Normal heating mat: However, this system would probably only make sense in the bathroom, as it is rather intended for small rooms up to 10sqm. Experiences?

Has anyone applied one of the three systems at their place? Can anyone say something about the costs and whether it makes sense?

Thanks

Good day,

1. Milling technique: chiseling out tiles (not a big deal, as we will probably change the flooring anyway). Afterwards, a "groove" for the pipes is milled into the screed. In the end, a leveling compound must be applied and the floor can be installed. Experiences?

That sounds like a workable method. Usually, it should work well.
The most expensive part is the milling. A normal underfloor heating system can be installed there.
The problem arises with the supply line. For that, the heating system would have to be adjusted as well. How do the heating pipes reach the rooms? Is the heating system located far away? Can a mixer be retrofitted?
That won’t be cheap.

2. Uponor low-profile system. Allegedly, the system can even be glued onto the existing tiles. Overall, it is supposed to be only 10-15mm high. Experiences?

Such systems are usually much more expensive than normal underfloor heating. These special solutions are quite costly.
If the old covering is left in place, another 15 mm build-up plus X mm for the new flooring comes on top. That quickly adds up to about 3 cm, which causes problems in other areas. The doors have to be adjusted. There is a small step to the other rooms.

3. Normal heating mat: This system would probably only make sense in the bathroom, as it is rather intended for small rooms up to 10 sqm. Experiences?

A heating mat powered by electricity? Running costs will eat your hair off your head.

Surface heating can be installed not only in the floor but also on walls and ceilings. Wouldn't that be another option?

Thank you for the response. I have just received an offer for milling technology. It should cost about €2700 (based on my specifications). The prerequisite is that the screed is 4mm or higher and that there are no pipes in the screed. The heating system is located at the very top of the house in the attic. Currently, there are a total of 3 radiators in the living room and kitchen. According to my information, option 2 is really significantly more expensive.

Wouldn't it possibly be more advantageous to completely rebuild the screed in the two rooms and then have the opportunity to install proper insulation underneath (if it doesn't already exist)? Tearing it out can possibly be done yourself; I did that in my bathroom as well. However, there was already underfloor heating there; I only removed the screed because I wanted the heating to run into the new floor-level shower (maybe you want that too?) and patching it is not recommended. My bathroom is smaller, but tearing out the screed took a little more than an hour. The longest part was disposing of it in the container.

Yes, we also wanted to install a floor-to-ceiling shower. But I don't quite understand what is meant by "anstückeln".