I had a concrete screeded floor with tile adhesive. I have removed thetile adhesive which was a nightmare but now have the following problems:

1, Some areas the screed is falling apart, should I remove the screed down to damp proof membrane and re-screed or use a different product?

2, Most areas of the floor there are little hollows which are too deep just for slc - is screed the correct thing here as there is not much area or depth in most cases?

3, What product can I add to the screed to speed up drying time so I don't need to wait 2 months before laying the new floor.Adding a floating wooden floor on top if that is relevant.

4, Do I need to wait a set amount of time before adding slc?

5, Do I need to primebefore adding slc?

And finally, possibly a stupid question...

6, if slc is only 1mm or 2mm thick in places will this be a weak area?

Andy

Hi and welcome...you can get slc which does upto 50mm thick...

maybe some pics of the crumbling screed might help

Thanks for the welcomes!

First pic shows the hollow bits...
Second pic shows the crumbling screed - what you are looking at is the old screed to the right and the new extension screed to the left. It is the old screed that has crumbled at the join - probably from lots of bashing around when the extension was going up.

2012-01-30_22-07-42_179.jpg2012-01-30_22-07-17_539.jpg

How big of an area is the old screed

16m2 I guess

Please don't say take it all up!

Most of the screed is sound if now very uneven. The crumbling screed is only at the join and as you can see I have removed it back to the solid stuff again.

Bit of a hard call without viewing in person patching a screed that has gone right through like that can cause trouble and needs to be done by a trade (even then they can still fail) if it was mine would be tempted to remove and re screed

Been doing a bit of research, was going to use ardex a35 for filling the holes and the new screed, then we can use latex/slc after a day or two. Is there better screed given the smaller holes to fill that might be stronger?

You need to be careful if the patch is to strong it will work against the existing and vice vercer if you do patch and then intend to tile recommend you use a decoupler

Looking at the pic on the left which is the new screed, it looks weak...tap it to see if it's has any hollow areas.

Floated wood floor going on top, so I just need it level.

Both pics show the old screed, I was just saying the right pic also showed the new (untouched by me as no tile adhesive on it) screed on the left hand side! Hope that makes sense!

I will tap it anyways...