Karndean tiles lifting at joints - how best to fix?

[desertrose]

Hi all,

The Karndean flooring in my porch is lifting around the corner joints in particular:

This is a south-facing glass porch that needless to say is exposed to extreme temperature differences. I think the floor was installed in 2015 or 2016.

You can see I've lifted the worst-affected tile, which lifted pretty easily, and it looks like whatever was used to level the concrete floor underneath has failed, rather than the adhesive:

It doesn't affect the whole porch area but about 1.5 square metres of where it gets walked on.

Thoughts welcome on how best to rectify would be much appreciated, please! If memory serves, have a few spare tiles and trim pieces, if that would be helpful.

Thank you.

 

[dazlight]

Looks like the screeding compound has blown. What was the sub floor ?

 

[desertrose]

I think it's just concrete from the original (70's) build. It looks like it's been coated with something by the installers for it to have the colour in the first photo, though. I have vague memories of some sort of black coating/adhesive before installation - you can (I think) see remnants of that too.

 

[desertrose]

Perhaps the easiest fix would be to try and use an adhesive to re-attach the original floor and newer screeding compound - any recommendations for what might be a good product for that, please?!

 

[dazlight]

You need to uplift all that area and throw it away. Uplift the Karndean till the screed stops coming up. Then rescreed and relay new tiles