Having underfloor heating milled in afterwards. Experiences!!!

I am trying to find people this way who have actually had underfloor heating retrofitted by milling. And then of course I want to know if they are satisfied with it or even regret it.

If possible, I would like to ask you to only write if you have experience with it and not to discuss the sensibility of such a project or alternatives.

Thank you all

I would like to highlight this topic once again. Maybe by now someone has gained experience.

Hello questioner. What do you mean by "retroactive milling"? Is the underfloor heating already integrated (where? Screed or concrete, both are possible for me) or do you want to mill the groove into an existing screed for a retrospective embedding of the heating elements? Regards: KlaRa

I'll join in: since an older bathroom in the family is going to be renovated, it would be nice to retrofit underfloor heating on this occasion (only in the bathroom). By removing the radiators, the main goal is to gain space, especially on the wall. I suppose that the existing screed would have to be milled out for this - or would it be better to remove it from the whole room? What would need to be considered?

I suspect that you would have to mill out the existing screed for this - or would it be better to remove it completely from the entire room? What should one pay attention to?

To the local conditions! Do all the sanitary fixtures remain in their original places? If not, screed work might be necessary anyway. In addition, you have to look at the condition. The disadvantage of milling out is that optimal thermal insulation downwards is not possible, and upwards the tiles may not be heated completely evenly. For a 5m² bathroom, this is probably not so bad, but for 20m² you have to make sure that the heating load is sufficient. Milling always produces a lot of dust and dirt, which is so fine that it travels everywhere. Therefore, it might well be that chiseling out produces less dirt than milling (despite suction). Honestly, I cannot judge the price.

To the questioners:
The valuable hint, or rather the crucial question, came from "86bibo" whether all sanitary objects should remain in the same place.
If the answer is no, it would actually not make sense to "tinker around" with the screed in small areas. However, installing a new screed will not give us the height needed to install a normative warm water heating screed with necessary thermal insulation.
There are also special solutions here, for example the SCHÜTZ R50 system, which requires only about 50mm build-up height (+ floor covering + adhesive bed) together with the thermal insulation.
Retrofitting grooves into screeds is, however, a critical matter. It inadvertently creates a multitude of predetermined breaking points and thus structural weaknesses. I once supervised this retrofit structurally on a concrete floor slab with core heating. That works because we can only go 2cm deep and the floor slab was sufficiently thick.
With existing screeds, we never know if the normative thickness is given! If we further weaken the structure, the screed panel will crumble apart at the first walk and will only be held by the tiles with their adhesive.
For retrofitting a small bathroom, however, another solution is recommended, which is safer and dust-free: an electric foil heating.
These come with a room thermostat, add only about 3mm in height, and are laid only (!) under ceramic tiles in the adhesive mortar.
That would also be a solution I can recommend.
The electricity costs, well, for a small room these will remain within limits, especially since heating with oil or gas also causes costs.
And the system works; it can be regarded as "state of the art."
Greetings to all: KlaRa