ᐅ Seamless concrete-look flooring for interior and exterior use

The following is planned:
A living area with an adjoining open kitchen and glass facade leading to an adjacent terrace are to be unified by a floor with a concrete look.
I deliberately use the vague term "concrete look" because even after extensive research, I am still not clear which of the possible options is the most suitable.
I hope someone here can help me.

The situation:

• Living area:
• Existing floor structure: concrete slab, screed with underfloor heating above, tiles on top
• Kitchen:
• Existing floor structure: wooden plank floor on joists. The planks are level with the tiles in the living area.
• Challenges:
• The kitchen has a low ceiling height (2.10 m (6 ft 11 in)), so the floor build-up should be kept low.
• Additionally, underfloor heating should be installed, preferably between the joists to save height.


• Terrace:
• Existing floor structure: rough sandstone slabs on a sand/gravel bed. One step lower than the floor level in the living area.
• Challenge: parts of the terrace are exposed to rain and snow; water must not penetrate into the house.

What techniques and materials would you recommend for the different areas to create seamless floors with a concrete look?
Thank you all in advance for your efforts and suggestions.

Maybe this post fits better under Screed-Floor Coverings-Tiles-Parquet? Perhaps someone would like to move it?

You will definitely need an expansion joint after a few meters. At least all the floor coverings we have looked at require it. We are now moving on to poured asphalt bitu-terrazzo. Here, you only need a joint for large areas. Poured asphalt has a very low build-up.

In principle, I would recommend a screed. Sand, seal.
Expansion joints in traditional cement screed can be filled with resin. Alternatively, use an anhydrite screed, which doesn’t require joints and has a similar appearance. Cast asphalt is the most expensive option and probably not the desired look.
If all else fails, fake can help. Concrete-effect plaster or paint plus a sealant. Anyone familiar with real exposed concrete will immediately recognize the fake, others won’t. But it’s not cheap either.

SWhof321 schrieb:
A living area with an adjacent open kitchen and glass front with a connected terrace should be unified into one space with a concrete-look floor.

Check here, this topic has already been discussed: https://www.hausbau-forum.de/threads/sichtestrich-oder-fliesen-in-beton-optik.25487/

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Thank you for your feedback and the link to that very informative related topic.

We have since decided against seamless floors and exposed screed:
- We couldn’t find an option that would look the same both inside and outside.
- The floor coverings apparently need to be regularly re-impregnated and are sensitive to abrasion.

Therefore, we are now leaning towards 60x120 cm (24x47 inches) tiles in a concrete-used-look. These are available in 10 mm (0.4 inches) thickness for indoor use and 20 mm (0.8 inches) for outdoor use.

However, this raises new questions:
1. The tiler wants to lay the new tiles directly over the old ones in the living area. Is this common practice or more of a shortcut? How does this affect the underfloor heating? Personally, I would have removed the old tiles (but left the heated screed), especially because of the transition to the kitchen, which already has a very low ceiling height. But the tiler says that would make the floor too uneven. What do you think?
2. If we keep the heated screed (with water-based underfloor heating), is it possible to add an additional loop to supply the kitchen? Otherwise, I can’t get the heating water into the kitchen.
3. For the 20 mm (0.8 inches) outdoor tiles, do they need to be fully glued down, or is a raised pedestal system also an option?

I’m looking forward to hearing your expert opinions.
Thank you in advance for your insights.