Very messy parquet laying work - Is rework not possible?

Actually, these are tricky spots (Kork) but definitely easier to implement better. The baseboards are, in my opinion, beyond any standard (paint pot tipped against the baseboard?)

But I really spent more than 2 hours on a single transition, sawing and sanding until the narrow parquet piece for the transition fit exactly to the millimeter. Pressed in, checked if it fits, corrected until it was perfect. Then put in, glued and screwed (hole pre-drilled, countersunk, special screws shortened with a tiny head etc.). You see the transition every day and it bothers you especially if you know about it or can’t overlook it. Just the same at the transition from parquet to tiles to the bathroom. That was very tedious because I had to repair the substructure several times to adjust it exactly to the screed height to the millimeter (I had to slightly raise it). That took me half a day. Afterwards, the painter applied sealant into the narrow, exactly parallel-running joint—I think it’s perfect ;-)

Maybe he simply didn’t feel like it or had no time for it? Doesn’t matter, you would have paid if he had said the transitions are somewhat complicated and he needs a bit more money if it’s supposed to look really nice—right?

Now about how you might repair it...

Remove the cork completely, clean the joint and straighten the edges of the adjacent parquet (Japanese saw, sandpaper + lots of patience). Then saw a parquet piece exactly shaped like the joint (craft work) and fit it in one piece. Visually certainly better because it fits better. It (in my opinion) then looks as intended and if you do it perfectly to the mm, certainly better than the current condition.

The cork joint could be a bit narrower, but in my experience it is within the standard craftsmanship. I also find it acceptable in terms of execution quality, as I have seen quite different work delivered by professional companies – and it was within the standard. For such large surfaces, a sufficiently large expansion joint is needed; a few millimeters are definitely not enough for solid wood. How much depends on the material, the substrate, and the installation. "2 mm of expansion joint per meter of floor should be observed. For a room measuring 4 x 4 meters, the edges of the parquet should therefore have an 8 mm gap to the wall." Regarding the baseboard, the question is what was contractually agreed upon. And as already mentioned, nice costs extra. As a correction, I would demand that the baseboards in the window area be revised. The short piece could easily be reduced in thickness and adjusted. Below the window, a cork joint might also be more appealing than the flat baseboards.

These are actually tricky spots (cork) but definitely easier to implement better. The baseboards are, in my opinion, outside any norm (paint can tipped against the baseboard?).

But I really spent more than 2 hours on a single transition, sawed, sanded until the narrow parquet piece for the transition fits exactly to the mm. Pressed it in, checked if it fits, corrected until it was perfect. Then inserted, glued, and screwed (pre-drilled hole, countersunk, special screws shortened with a tiny head, etc.). You see the transition every day and you especially notice it if you know about it or cannot overlook it. Just like the transition from parquet to tiles in the bathroom. That was very tedious because I had to repair the subfloor multiple times to adjust it exactly to the screed height (I had to raise it slightly). That took me half a day. Afterwards, the painter applied sealant into the narrow, precisely parallel joint – I think it's perfect ;-)

Maybe he simply had no desire/time for that? Whatever, you would have paid if he had said the transitions are a bit complicated and he needs a bit more money for it to look really nice – right?

Now on how you might repair it ...

Remove the cork completely, clean the joint and straighten the edges of the adjacent parquet (Japanese saw, sandpaper + lots of patience). Then saw a piece of parquet exactly so (craft work) as the joint is shaped and fit it as a single piece. Visually certainly better since it fits better. In my opinion, it then looks intentional and if you do it perfectly to the mm, definitely better than the current state.

Cork: I exactly thought about that. Unfortunately, he did not leave any planks, but I know the exact designation and would order the smallest quantity (2.44 sqm / 6 planks) elsewhere if the floor fitter refuses or claims that no planks were left over. That would certainly be the most cost-effective option. The somewhat more expensive one would be to replace all the planks at the transitions.

I found thinner baseboards in the same color and height. I would install these in the window area. Visually, no one will see whether they are 1.8 cm or 1 cm wide. It will certainly look better.

Would it be worth asking my building surveyor, who accompanied the entire house construction (unfortunately I did not commission him for this trade), for an expert opinion and then see a specialist lawyer for construction law? I doubt that the floor fitter can/wants to rework these jobs. I am happy to pay for work that is well done, but not for this. The invoice is over 24,000.

The cork joint could be a bit narrower, but in my experience, it is within the craftsmanship norm. I also find the quality of execution okay; I have seen much worse work delivered by professional companies – and still within the norm.
For such large areas, a sufficiently large expansion joint is needed; a few millimeters are definitely not enough for solid wood. How much depends on the material, substrate, and installation. "2 mm expansion joint per meter of floor should be observed. So, for a room sized 4 x 4 meters, the edges of the parquet should have an 8 mm gap to the wall."
Regarding the baseboard, the question is what was contractually agreed. And as already said, nice costs extra. As a rework, I would demand that the baseboards in the window area be revised. The short piece could easily be reduced in thickness and adapted. Underneath the window, a cork joint might also be more appealing than the flat baseboards.

He can’t do better, constant statement “can’t do it.” The method with the cork is outdated. One must keep up with the times. I pay enough for a perfect execution. I would have rather hired the big modern parquet company than this small outfit that stopped evolving in 1980. The offer was the same.

He can’t do better, constant statement, it’s not possible. The method with cork is outdated. You have to keep up with the times. I pay enough for a perfect execution. I would have preferred to hire the large modern parquet company and not this small place that got stuck in 1980. The offer was the same.

Then that is your problem. If you did not specify the execution in the contract, you cannot say afterwards that you wanted it differently. What does the order say about the execution of the joints? The moldings? And even in 2023, recommendations and standards apply for the width of movement joints in parquet. A modern company also cannot reduce them to 2 mm. Or omit them. The method is hardly outdated. We recently supervised the renovation of a property where an absolute premium floor was newly installed in a prestige project. And yes, all movement joints of the approx. 200 sqm were executed in cork.

He can't do better, constant claim that it doesn't work. The method with the cork is outdated.

I agree and it definitely can be done better. Since you are in NRW, would you maybe specify the location more precisely? Within a radius of Wuppertal (+/- 50 km), for example, I could recommend a real professional who knows what he is doing with the appropriate quality standards. Also, you don't have to give away your last shirt for it ;)

So before you start tinkering, have the entire parquet strip replaced at the transitions and you will be happy.

Then that is your problem. If you did not specify the execution in the contract, you cannot later say that you wanted it done differently. What does the order say about the execution of the joints? The moldings?
And even in 2023, recommendations and standards apply for the width of expansion joints in parquet. Even a modern company cannot reduce them to 2 mm. Or omit them.
The method is hardly outdated. We recently supervised the renovation of a property where an absolute premium floor was newly installed in a prestige project. And yes, all the expansion joints of the approximately 200 sqm were executed with cork.

My problem is that I want it to look nice? There is nothing about that in the order. I was not informed about the joints and moldings before the installation. I was not informed that it doesn’t fit at the windows. It was just done. It’s 100 sqm. Go to Parkett Dietrich or something, then you can see how they installed the parquet continuously. It is a new building and not an old house!