The screed has cracked - Arrgh! Must I dig it up?

[diyblonde]

Hi there, we've knocked out a wall to extend the kitchen. A bit of the 'new' floor needed to be raised to the height of the kitchen floor which my boyfriend screeded 10 days ago. Now it has cracks in it - horizontal and vertical. It is a small old passage area approx 1.5m x 80cm - he did not pull up the existing tiles in the area before he screeded nor did he use a bonding agent. The rest of the kitchen floor is sound and this is just a bit 'added on' after we got rid of the wall. We will have to put self leveller down on the whole kitchen floor and the 'added on' bit before we put the wooden floor down.

Should he pull it up and start again?
If so should he then remove the tiles underneath before screeding a second time?
Or can we just put self leveller over it all and then put down a wood floor after the necessary 30 day drying off period?

 

[masona]

Should he pull it up and start again?

Yes

If so should he then remove the tiles underneath before screeding a second time?

It's best to, what is the floor thickness difference

 

[diyblonde]

what is the floor thickness difference

Helloo - The passageway floor area is approx 2" lower than the kitchen floor. He put screed over the tiles to match the level of the concrete in the kitchen.
He has taken off the layer of leveller in the kitchen and we were hoping to just put self leveller over the kitchen and newly screeded passage bit (and possibly put a DPM under the self leveller) ... but now its cracked!

And by the sound of it just putting self leveller over the cracks may not be a good idea?

I read somewhere that fibre strengthens screed? I asked him if he'd put fibre in the screed mix - he said he knew that he probably needed fibre but didn't put it in

Love the guy but really! Which is more trouble driving to the shop to buy fibre OR ripping up the screed it took him over an hour to do and then relaying it! Although I don't know if the fibre would have helped the problem if it is actually the tiles underneath that are causing the cracking.

 

[masona]

50mm should be okay, did he use sharp sand or maybe it's a weak mix?

I'm poping out for the rest of the day so hopefully someone can help you shortly

ps: found this //www.diynot.com/forums/viewtopic.php?p=339565