Have underfloor heating installed beneath existing floorboards

We have an old building from 1934 with great pitch pine floorboards on the ground floor and would like to have underfloor heating installed using the milling method. Does anyone have experience with removing and re-laying the floorboards after installing the underfloor heating? Is that even feasible without additional build-up height? Thanks for any tip!

Milling process would mean that there is a screed under the floorboards. This would imply that the floorboards are glued and most likely cannot be removed without damage. However, in the picture, it appears that the floorboards are nailed. That means there must be some kind of wooden substructure. Depending on what it looks like and how high the infill is, a floor heating system without increased installation height can be realized using a renovation system such as from Ripal. From my own experience, I can say that removing floorboards without damage requires very careful and conscientious craftsmen.

1937 with the floorboards definitely has no screed underneath. The floorboards are nailed to battens. These usually rest on a sand bed. Partially, this was/is also ventilated, recognizable by usually small grates covering DIN A6-sized openings on the outside of the exterior wall at floor level. As the owner of an even older house with similar floorboards, I can assure you that you cannot remove the floorboards there without damage.

If the floor is stable, does not wobble, has not sagged or the like, I would leave it as it is. Instead of underfloor heating, you can use fan-assisted convectors in these rooms. (e.g. Daikin Altherma HPW). They operate at 30-35° supply temperature and you can run them without an additional mixer along with underfloor heating in the other rooms via a heating circuit distributor if you want to install a heat pump. Seal the ventilation openings from the outside with mortar, otherwise you'll have cold feet in winter.

1937 with the floorboards definitely has no screed underneath.

My house is from 1914 and I partially had a kind of screed under the floorboards on the ground floor. Not concrete screed but some mixture of sawdust, sand, glue and who knows what else. It was definitely no fun to remove. The floorboards in that area were actually glued, but not full-surface. The wish of the monument preservation office that the floorboards be preserved and relaid was quickly dropped. The rest of the floor structure is as you described with sand as filling. A underfloor heating system can be installed well there.

Thanks for every tip!

I just saw your forum name. If the house is in Eutin, and you generally need some advice on renovation, etc., get in touch with the municipal utilities and ask for Till or check my direct number on the homepage.
(But I won’t be back in the office until 01/08.)