Bette Floor shower tray flush installation - not recommended

Hello everyone,
just before the screed is laid here, our plumber advises against a flush-mounted/thresholdless installation of the Bette Floor shower tray despite prior agreement. He says there would be an unsightly silicone joint between the tiles and the shower tray because the shower tray has a rounded edge on top.
According to the manufacturer, it is suitable for flush installation. I have now seen that our plumber wants to install the shower tray on the screed using the minimum tray support. According to the manufacturer's drawing, this is only possible with a raised tray, so about a 25mm threshold. For the flush installation, a universal support is recommended, which stands directly on the concrete slab and can be adjusted to the screed afterwards. In my opinion, you could then also set the height of the tray so that the rounded edge slightly overlaps the tiles and they rest just below the rounded edge.
The plumber says that for flush installation, the screed must be exactly leveled, which is difficult and can also go wrong. Of course, he is also using the non-height-adjustable installation variant.
Has anyone of you installed this tray flush or has an opinion on the procedure? Our screed is coming tomorrow and I feel that this call a day before is more a tactical move. We are building turnkey with a general contractor and the flush shower tray was in the contract and also included in the bathroom selection from the start.

Has anyone of you installed this tub flush with the floor or have an opinion on the procedure? Our screed is coming tomorrow and I have the feeling that this call a day before is more of a tactic. We are building turnkey with a general contractor and the flush-mounted tub was in the contract from the beginning and also in the bathroom sampling..

I don't have the tub, but I would be relaxed in your place. The tub is part of the contract. The question is rather whether you could live with the silicone joints and whether that would cause a dispute... Addendum: A call is not enough to register concerns. If he has concerns, he should please submit them in writing, stating that he believes he cannot deliver the contractually owed work. Then you can discuss it together. Calls are always bad because they are hard to verify in content and in the end, the parties always remember different contents.

We had our shower tray from Bette Floor installed open and flush with the floor 9 years ago and are still satisfied. The only thing I can report negatively so far is the drain. I believe that due to the combination of the drain clogging quickly and the slight slope (the drain is installed in the middle and the narrow side is drained), it has to be cleaned every week, otherwise the water tends to accumulate. No idea if this is the case with shower channels as well. One has to be aware that even though the tray looks solid, it is of course a tray with a corresponding "hollow" sound. That can be a bit surprising at first. Good coordination between the tiler, plumber, and drywall installer was necessary during installation since we installed the shower tray on 3 sides. On the one hand, there was no stepping surface to hold the shower tray, and on the other hand, there was no space. The bottom row of tiles on the partition wall was therefore only installed after the shower tray was fitted.

Here are 2 more pictures of the shower tray.

I don't have the tub, but I would be relaxed in your position. The tub is part of the contract. The question is rather whether you can live with the silicone joints and whether there will then be arguments about it...

Addendum: A phone call is not enough to register concerns. If he has concerns, he should please submit them in writing, stating that he believes he cannot deliver the contractual work. Then you can discuss it together.
Calls are always bad because they are difficult to prove in terms of content, and in the end, the parties always remember different things.

A silicone joint is indispensable, even if I let the tub stand over/on. The silicone joint around the corner seals better and/or is cleaner. My main concern was that the manufacturer's specifications are not being followed and that it is supposed to be installed flush with the floor on a carrier that is not suitable. I have now also received the records of yesterday's surveyor visit, who clearly states that the tub, if installed flush with the floor, must be placed on feet that can be adjusted afterwards – so this confirms my thoughts. Just the fact that, as a layperson, I have to worry about these issues when I build turnkey. In my opinion, the plumber is not exactly acting properly, especially with his statements to me – it seems rather as if he wants to discourage me from a flush installation.

I am always doing everything in writing in parallel – the plumber also informed me in writing that I am acting against his advice :D

Here are 2 more pictures of the shower tray.

That is super helpful, especially the pictures. Thank you very much! It strengthens my belief that it can work without problems.

Interestingly, for me these are the joints that have not yet cracked or come loose in the house. In many other places, I have had to renew the joints due to settlement cracks after a few years and would sometimes have to do it again. Whether it is due to different silicone or good adhesion to the shower tray or because the silicone never dries out from showering, I do not know. Maybe it is also because the tension can spread over large areas, as the shower tray only lies more or less loosely on the support.