Leave the old wooden floor for the bathroom without additional construction?

Hello everyone, I am a newcomer here (please forgive me any beginner mistakes...).

We are taking over a house from the 1930s from family, which is in good condition and any necessary repairs have always been carried out promptly.

In the house (2 floors plus basement) the ceilings on the 1st and 2nd floors are made of wood, so the original plank floors are present there. Their condition is good, of course we need to sand and seal them all again so they look nice.

On the 1st floor we want to build a bathroom in a room previously used "conventionally" (office/children’s room, etc.), the necessary water pipes can be laid there easily from next door, and the entire house’s electrical system will be revised by a professional company anyway.

In some instructional videos I have seen that you can build a bathroom in a room with wooden floors using different floor builds (impact sound insulation, OSB boards, Fermacell boards, sealing compound, possibly tiles). What bothers me is the height of the whole build-up, which would end up about 100mm higher than the original floor. And there is also a small step at the transition. The additional load on the ceiling should also remain as low as possible.

Is there not an option to sand and treat the original floor (with a nice look in the end), but also seal it to install the bathroom there? Of course, no moisture should get into the floor later, that’s obvious. The walls will be tiled.

Does anyone have tips for my project, or is something like this fundamentally impossible? How did you solve it?

Thanks in advance!

So basically, there is the possibility to make wooden floors "sealed," but there is always a certain risk that moisture will eventually seep through, especially in the joints and corners. However, there are also pretty cool floors that visually fit well into an old building, and keep in mind that most bathrooms in old buildings do not have wooden floors! It can really be that a classic bathroom renovation with floor replacement is cheaper for you than conducting some experiments with sealed wooden floors here.

Great, thanks for the tip!

I'll take a look.

Hello questioner. You may receive answers here that come close to your intention. However, that is not productive! Your question: "Besteht nicht die Möglichkeit, den originalen Boden zwar zu schleifen und zu behandeln (mit schöner Optik am Ende), aber auch abzudichten, um das Bad dort zu installieren?" must be answered from a technical standpoint with an NO. Without any IFs or BUTs. ------------------------------------- Regards: KlaRa

In shipbuilding, one also faces the problem of sealing wood watertight; otherwise, you couldn’t build boats from native woods, only from the highly oily tropical woods. The classic method was clear lacquers based on turpentine, such as Le Tonkinois or International Schoner Gold. More modern would be mono urethanes, as offered by Hempel or Epifanes. These lacquers are more durable when walked on with footwear. In both cases, the application is labor-intensive; you must apply about eight coats, starting with a half-and-half dilution of thinner to lacquer, ending with 10% thinner. Damages must be repaired immediately. The result is not particularly slip-resistant, rather very slippery when wet. Conclusion: It works, but it is not really practical for domestic use. Karsten

What nonsense! (Sorry) We do not have the task in this forum to derive an alternative for residential construction from exotic solutions, but rather - as far as we have the expertise - to provide answers based on the rules of the profession that allow damage-free construction. Anyone who derives from shipbuilding to old wooden floorboards that are also supposed to be used in a wet room cannot possibly know the rules of the profession. Just hold back if you are not sure when answering. And in case of ignorance, leave the answers to those who are professionally very familiar with the medium and who know the professional rules. ----------------------- KlaRa