Cracked Travertine

[stevl]

Hello! I have some serious cracks in my basement floor and was wondering if anyone would be able to advise on the best way to investigate & hopefully repair?

The floor is travertine tile laid on approx 40mm of anhydrite screed using flexible adhesive. The screed contains wet underfloor heating and sits on top of 50mm celotex and is also insulated around the edges. The floor was laid around 8 years ago so I don't remember the details but it was left to cure for the required time (3 weeks??) and then brought up to temp slowly.

There are 3 heating zones but no expansion joints in the screed. Small cracks formed at the zone junctions after a few months. They got worse and more cracks appeared for around a year and the floor then seemed to settle, except in the bathroom. I have a walk-in shower and, although the initial crack was on the opposite side of the room, it looks like water eventually got in and the tiles have progressively separated along the grout lines to the point where cracks are now starting to form right near the shower (hence me finally having to do something about it!)

Can anyone suggest the best course of action here? I'm mainly looking at repairing the bathroom where it looks like most tiles have just come away from the screed (most sound hollow although I haven't tried lifting them yet) but there's probably also at least one crack in the screed.

Thanks!

 

[White Room]

Was a decoupling fitted ?

 

[stevl]

Nope

 

[White Room]

You would have need probably more than 3 weeks for that screed to dry out, looks like a lift and replace.

 

[Stef]

3 weeks for a 40mm gypsum screed to dry, not enough time for that to be sufficiently dry.
There's a lot of variables but that floor should have been tested prior to a floor covering going down on it.
Was the screed every sanded?

 

[stevl]

Thanks for the help so far.

The floor went down 8 years ago so not sure exactly how long it was left. Might have been longer than 3 weeks.

The screed wasn't ever sanded or sealed, and it wasn't tested either. Now that I think about it, I seem to remember it looking a bit different in the corner of the bathroom, like there was some residue on top. Maybe that's the reason for the de-bonding, not water getting in.

Suppose I need to lift the tiles and see what's underneath. Assuming the adhesive has debonded from the screed, should I sand (or seal?) the screed? Any recommended products?

I'm guessing a de-coupling layer is out of the question because I need to tie back into the existing floor and it'd change final floor height. So just lay some new matching tiles using flexible adhesive?

Anything that can/should be done about any cracks that might be in the screed?

Thanks!

 

[stevl]

Well, I finally got round to lifting the tiles and it looks like the anhydrite screed has turned to powder around the ufh pipe and the adhesive on the back of the tiles has completely debonded from the screed. I suppose, on the plus side, it should at least be relatively easy to remove the old screed.

Is there an alternative to anhydrite that would be suitable for a small area like this? The screed is very thin so normal sand/cement would be out of the question, unless I replace the ufh insulation with something thinner (maybe drop from 50mm down to 30mm??). Need to have a think about where to go from here!

 

[Time's Ran Out]

Looks as though the wet UFH is not spaced correctly and too close to the surface.

 

[WetSaw]

No decoupling either...

 

[stevl]

Do you think reducing the insulation to 30mm and replacing the anhydrite with 60mm of normal sand/cement screed plus a decoupling would be the way to go?