Why are the silicon joints breaking around the bathtub?

Why are the silicon joints breaking around the bathtub? What can be done better there?

The tiler has to work there on the tub. He will tell us that the installer is to blame, who puts his tub in elastic polystyrene foam and there it sinks deeply when filling with water. That can no longer bridge silicone.

Daddy thinks it's only Mutti's clean cleaner.


Some people say the tiler did not clean the joints properly and primed them.

No, most of the time it's a completely different reason!

On the two pictures it is good to see that there are some joints with silicone "filled" Has.


Silicone is visible on the long side, which is about 7 mm wide. The horizontal gap on the head side of the tub can only be seen with a width of about 3.5 mm.

Are these joints so wide?

Nope!


Both joints are only 1-2 mm wide, from tub to tile, everything else is just "lubricated" over it.

It lacks the correctly calculated joint width and almost every German bath the prescribed backfill.

Sealants such as silicone may well be slightly stretched, i.d.R. but not more than 20%. That is not much!

So when I set up a tub, I have to leave plenty of room for the joint sealant.

And - with a clearance of 10 mm to the wall, the joint sealant may be stretched a maximum of 2 mm before it breaks.

But how do you bring the silicone into such a gap?

You first insert a "backfill cord", depending on the product, a separating strip and only then fill the joint with sealant.

For real expansion joints we would have to have really big silicone strips in the bathroom. This does not look so good, so it is adapted to the 4mm tile joints and then of course breaks.

Of course, the alternative with sealing lips is also available, but normally you decide for one of them:

Optics or tightness!

How to Apply Silicone - the COMPLETE Pro Guide | March 2024