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

Hello everyone,

In my newly built house from 2024, where we have been living for a year now, we installed the bathroom ourselves with the help of friends who are professionals (including a tile installer). We used very large format tiles.

Because of the walk-in shower without a shower tray, the shower area, as well as the entire bathroom, was waterproofed. Multiple layers of PCI Lastogum were applied, and of course sealing sleeves and waterproofing tapes were used at the transitions to the walls and in all corners. Underneath is a cement screed.

Recently, I happened to read that Lastogum is no longer approved for floors in such showers for a few years now. I have some questions about this:

1) Why was this changed? Were there any incidents? Why was this considered sufficient for decades before, but not anymore?

2) What about houses that were waterproofed the same way 8 years ago? Is there a reason to make corrections, or should nothing be done?

3) Specifically for me personally: should I consider opening up the floor, installing a waterproofing membrane afterwards, and then re-tiling? Or would that be excessive, considering it was only done a year ago?

4) Is there anything I should regularly check or monitor to detect major damage early?

Thank you all!

Jschm88 schrieb:

I just happened to read that lastogum is no longer approved for floors in such showers for a few years now.

Says who?

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

Just checked.
The manufacturer specifies it for "wall and floor."
In the building authority approval, it is listed as wall only.
For the DIN standard, it seems to apply only to walls, but for the Austrian standard, it also applies to floors.
It looks like the German inspection authority is somehow objecting here.
However, the manufacturer believes it is acceptable.
I wouldn’t worry about it either.

Hello, and thanks for the quick feedback.

I read it somewhere, but I don’t remember where. Then I checked with the manufacturer, who suddenly labeled it as "for wall use only." Apparently, there is a new DIN standard...

Therefore, I’m interested in the reason behind this and whether I should be concerned or take any preventive measures. Based on the previous answers, it seems like I can relax for now, but it would still be interesting to find out what changed there and why!

Additional note: I found a document from Weber that explains the "New Waterproofing Standard from 2017" and also includes various FAQs.
The DIN standard only approves polymer dispersions (liquid plastic waterproofing) for water exposure class W2-I (which includes walk-in showers) for walls. It does not explain why, so you probably need to contact DIN for clarification.
If you are paranoid, you can either

• install a shower tray.
• remove the tiles and also the first 20cm (8 inches) of the wall tiles, since you would need to waterproof the transitions again. Then apply either a waterproof membrane or a mineral-based flexible waterproof slurry.

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

It is always difficult for a layperson to judge something without reasons, sources, or reliable knowledge.

Jschm88 schrieb:

Or would that be exaggerated?

Certainly, that would be exaggerated. How many houses were built with asbestos before it was banned? And how many homeowners have since removed their roofs or façades because of the ban? Even older timber-framed houses soaked with formaldehyde are still standing.

So whatever the reason for no longer using the product: enjoy your bathroom!