Bathroom wall with leca in basement

[mlitsgard]

I have an unheated laundry room in the basement with a shower corner (brrr) and I'm now thinking of dividing it and making a real bathroom. I plan to build the new wall with 15 cm lecablock. A couple of questions that I haven't found answers to anywhere:
1. Should there be a moisture barrier between the wall and the concrete floor, or should it be built directly on?
2. Does the wall need to be reinforced? It's quite thick and non-load-bearing, but maybe it's still necessary?

 

[norrbottenstorpet]

First post, welcome to byggahus.

Do you have a modern well-drained basement, where the slab can be assumed to be more or less moisture-free? Or are we talking about an older basement where the slab may have been laid on "anything" that was available when the house was built?

If you have extensive moisture migration (read older house) in and under a slab, I would not primarily seal that moisture in but have as diffusion-open a construction as possible. In other words, only moisture-proof the actual shower corner in the new bathroom.

You should prime the wall itself before you start building, to ensure it adheres well. I would also reinforce the wall, both between the layers and where it attaches to another basement wall.

 

[mlitsgard]

Thank you for the welcome, it's fun to write something myself, I've read a lot...

The basement is old (1930) but recently insulated and redrained, so at least it's dry now. I've read that I should be careful with moisture barriers on the floor and outer wall, only in the actual shower corner, as you write. From what I understand, I should also put a moisture barrier on the interior wall on the bathroom side. My question was whether I should try to prevent moisture from the slab from going up into the wall, but I shouldn't, then.

 

[J.B.]

I had placed syllpapp under the wall so you don't get any moisture up in the wall from the slab, but any rising moisture can come out into the room.