Bathroom - Do I Dare to Tile?

[J0naz1]

Dare I tile the bathroom, or is the risk of settling too great?

I have built an Attefall house that I am currently furnishing.
The part where the bathroom will be is built on concrete piers. About 1-meter deep holes with 10 cm of gravel at the bottom, then a 40x40x4 cm garden slab and poured 15 cm diameter posts on top of that (i.e., about 90 cm long posts underground).
I am in central Sweden, so it's not certain if it's frost-free.
The ground consists of almost 100% sand. It's very well-drained, although the construction is in a dip on the plot.
So, during wet periods, spring/autumn, the "groundwater" rises to about ground level (15 cm below the crawl space floor).

The bathroom is firmly screwed into the main building, which was built about 8 years ago and has settled a few centimeters. It's only placed on concrete blocks after excavating about 10-20 cm and having gravel.

In the bathroom, I have installed 12 mm OSB, with plywood in the shower area. Then I have screwed steel angles along all the floors and corner angles to avoid movement there. Then plasterboard.
The question is whether there is a risk of the building settling, which means I should have a waterproof membrane instead of tiling?

I would prefer to tile, partly because I like it more. I already have some materials and can also do the work myself.

 

[Jonatan79]

The building should have settled by now. The waterproofing can handle some movements, so it would take a lot for the walls to move enough for the tiles to shift/crack.

 

[J0naz1]

The building should have settled by now. Waterproofing can handle some movement, so it would take a lot for the walls to move enough for the tiles to move/crack.

Note that it was only the main building that was built 8 years ago. The part with the bathroom was built about 1 year ago.

 

[Jonatan79]

Note that it was only the main building that was built 8 years ago.
The part with the bathroom was built about 1 year ago.

I understand, you wrote that they are built together so that part shouldn't sink further.

 

[BirgitS]

I understand, you mentioned that they are built together so that part shouldn't sink further.

Couldn't one imagine that the bathroom is secured along one or two walls, but the support underneath disappears under one or two corners, causing significant movement in the angles between different walls?

In the bathroom, I have installed 12 mm OSB and plywood in the shower area. Then I've screwed steel angles along all floors and corner angles to prevent movement there.

How closely is it framed?

 

[Jonatan79]

Couldn't one imagine that the bathroom is firmly attached along one or two walls, but the support underneath disappears under one or two corners, causing large movements in the angles between different walls?

How closely is it framed?

Certainly, it is possible to check the situation and even lift part of the building if it has settled before tiling if it is really necessary.

 

[J0naz1]

Could one imagine that the bathroom is well-secured along one or two walls, but the support underneath disappears under one or two corners, causing significant movements in the angles between different walls?

How closely is it framed?

It is framed with about 30-40 cc.

There is a wall built together with the old part, so as you say, that shouldn't sink, but maybe the other long side, two corners. If it sunk a lot, it could result in substantial movements in the angles you describe.

Right now the room is filled with construction items, but I will clear it out eventually when I start the work. Then I will check to see if it has already sunk and I can probably lift it with a jack and support it under the piers.