Floor-to-ceiling tiled shower new construction not properly sealed

Hello everyone,

In my new building from 2024, where we have been living for a year, we installed the bathroom ourselves in collaboration with friends from the trade (a tiler was involved). Very large format tiles were used.

Because of the walk-in shower without a base, it and the entire bathroom were waterproofed. PCI Lastogum was applied multiple times, and of course, cuffs and sealing tapes were used at the transition to the wall and all corners. Beneath that is cement screed.
Now I happened to read that Lastogum has not been approved for the floor in such a shower for a few years. I have questions about that:

1) Why was this changed? Were there incidents? Why was something good enough for decades and now no longer?
2) What about houses that were waterproofed the same way 8 years ago? Is there cause for correction? Or do nothing?
3) Personally, should I go and at least open the floor, afterwards apply a waterproofing mat, and then re-tile? Or would that be over the top? It was only done a year ago.
4) Is there anything I should regularly observe to detect a major damage early later on?

Thank you!

Now I read by chance that lastogum has not been approved for the floor in such a shower for a few years.

Says who?

I keep reading funny things here that someone supposedly read somewhere... please don’t take this the wrong way, it’s not directed at you at all… but one swallow does not make a summer.

Just checked. The manufacturer states "wall and floor". The building authority approval only mentions wall. For DIN, it seems there is only wall, but for the Austrian standard, floor also applies. It seems as if the German testing authority is somehow obstructing here. However, the manufacturer believes it is acceptable. I wouldn’t worry about it either.

Hi, and thanks for the quick feedback.

Read it somewhere, but don’t remember where. And then also checked with the manufacturer, who suddenly stated "only for wall". Apparently there is a new DIN...

Therefore, I would be interested in the reason for this, and whether I should be worried about it or what I should do preventively. According to the previous answers, relaxing would be the first step, but it would still be interesting to find out what has changed there and why!

Addition: I have now found a document from Weber where the "New sealing standard from 2017" is described and various FAQs are included. The DIN, with the new standard, has only approved polymer dispersions (liquid plastic sealing) for water exposure class W2-I (which includes, among other things, walkable showers) for walls. Why this is the case is not explained there; you probably have to inquire with DIN. If you are paranoid, you can either

[*]put a shower tray on it.
[*]remove tiles and also the first 20 cm of wall tile rows because you would have to reseal the transitions. And then either apply a sealing membrane or mineral flexible sealing slurry.

I wouldn’t do anything there until a renovation is due anyway.

It's always difficult to judge something as a layperson without reasons, sources, or only half-knowledge.

Or would that be exaggerated?

Certainly, that is exaggerated. How many houses were built before the asbestos ban? And how many builders tore down their roofs or facades again after the ban? Even older timber-framed houses soaked with formaldehyde still stand.

So whatever the reason is that the product is no longer used now: enjoy your bath!