Self Levelling Help - slab split into two?

[Dean A]

After a few more hours of research, I notice some people suggest using Ditra, but just bridging the crack... this would bring the cost down to a more sensible level, but would this be effective?

 

[Diamond Pool Finishers]

i would say if you repair the crack like grumpy says, then SLC bulked-up to make it go further over the repair, then use ditra/shuluter then tile ......

 

[Dean A]

i would say if you repair the crack like grumpy says, then SLC bulked-up to make it go further over the repair, then use ditra/shuluter then tile ......

ditra/shuluter on the full 20m2 or just over the crack, spanning maybe 1/2 over the crack?

 

[bugs183]

You have to get this baby right, and it will cost, or it will cost you more later if the slabs move.
As everyone says the joint needs to be stitched. Angle grind at 90 degrees and insert threaded stitch bars (i think screwfix sell these, fill with Ecorip. Prime both slabs as said above and cut a 500mm wide strip of Ditra of Dural matting and fix this across the gap with flexible floor tile adhesive. You shouldn't need to use an uncoupling mat on the whole floor.
Level etc as above.
There is a chance the two slabs may move and the combo of stitching and the ditra should do the biz. We've done it between concrete slabs and from concrete onto wood floors, and touchwood we've had no agro.

 

[Diamond Pool Finishers]

i would go for 1/2 m ether side of the crack with uncoupling membrane .
not grumpy but Ajax i was referring to above sorry.....

 

[Ajax123]

Thanks for the reply.

The angle of the picture doesn't help, there isn't really a chasm, the two joints butt up against each other. There is just a height differential.

I haven't seen anything about a low viscosity resin stich in my research, is it quite common to use this method? I did consida Ditra matting as I have used this before, but at 20m2 it will add significant cost.

Resin stitching is a very common method of repairing unstable or fractured screeds.

 

[Dean A]

Thanks for all the advise.

I have taken another close up of the join.

The previous tiled floor was fine for the 3 years we have lived here, it would be sods law that it cracks for me after the laying the new floor!

 

[bugs183]

Yep you can bet it would move now!!!!

 

[Dean A]

I will probably do the lot in uncoupling membrane to be on the safe side, £200 is better spent now than trying to dig up the tiles later to fix

Appreciate all the help chaps!

 

[bugs183]

Not a bad decision. Belt and braces job!
Go to to www.radetiler.co.uk and use the durabase ci matting. Great stuff and a good price, and Dave's a very helpful fella. LAy the mat as above and leave overnight (even if you use fast set), and tile the next day.

 

[bugs183]

sorry it's Tradetiler.com Home

 

[Diamond Pool Finishers]

good -luck Dean

 

[bugs183]

Just reread the thread, Mapei Renovation is the best leveller i've used. Pours nicely, but i've not gone to depths of 30mm, it may take you a few pours over a few days to get it just right.

 

[Ajax123]

You could use a gypsum screed to 30mm but maybe that would just complicate things.....