Selflevelling cracking - TilersForums.com

[baht'at]

Hi all just asking if anyone else has come across selflevelling compound cracking and what they have done about it.
The floor in question is an old farm house and was a mixture of concrete and old type tiles but as walls had been removed these were all at different heights hence levelling.
The work was done by a contractor at the beginning of October with a maximum depth of 20mm in some areas ,But don't know what was used but by the splashs on the walls looks like normal bagged compound.
The heating in the building as been in operation for the last week but there is no UFH just radiators and I last saw this floor the first week of this month and it looked fine then, but a mate working on the same property has told me there are cracks now appearing in 4 areas of this floor.
The total area of this floor is 30sq m.
I am due to tile this floor starting 5- Dec but I have concerns if the cracks are appearing now could or will they continue once tiled over and what could the consequences be.
Any advise would be appreciated

 

[hmtiling]

How big are the cracks? I've seen ultra levellers have a load of miniscule cracks but still be sound. Pictures would help.

 

[baht'at]

How big are the cracks? I've seen ultra levellers have a load of miniscule cracks but still be sound. Pictures would help.

Thanks for the reply I'll try get some pictures but there 20miles away and and can only go at night just hope electricians put some lights in

 

[White Room]

How big are the cracks? I've seen ultra levellers have a load of miniscule cracks but still be sound. Pictures would help.

Had the same Harry.

 

[SJPurdy]

cheap levelling compounds are for thin layers only (not 20mm) and crack up when set if used thicker than they are intended for. I'd want to know what has been used before progressing.

 

[baht'at]

Thanks for all the replies .
Had to take time out today and go look at this floor as my mate says are getting worse.
Having now seen for myself it is worse than expected as there is lipage between some of the cracks and when tapped with my knuckles it sounds hollow so seems in some areas it has blown.
The work was done by a screeding contractor so would have expected they knew what they were doing in the first place.
Have informed the customer that I will not be laying the tiles until this has been sorted .

 

[LM]

Assuming that there is no issue with rising damp through a lack of a damp proof membrane with an old building like this then I'd say that there's a fair chance it's a water based slc with no primer used. It's hard to tell on my phone, but the sections of cracked slc look as if they're fairly thick and appear to rise off the floor. I've seen this countless times with people who didn't follow correct procedure. There is no way you can tile over this, it has to be removed, but this won't be hard. A simple scrapper pushed into the cracks will let you prise the slc up and remove it in sections. Make sure to degrease the floor and remove any contamination then prime the substrate with something like Ardex P4 then use a good slc to remedy the works before tiling.

 

[LM]

In fact with old buildings like this it may be worth giving the floor a coat of liquid DPM before you levell it just to be on the safe side.

 

[baht'at]

Thanks Lee.
I spoke with the owner of the property yesterday as he had organised the contractor ,who in my presence contacted them yesterday ,but the owner is away on holiday until next week and they can't inspect it until his return.
The owner did mention he had been informed that the old surface had been mechanically cleaned prior to the screed being laid and I would have assumed that some form of primer would have been used as I normally do when I have used SLC before but on smaller areas.
As I hadn't seen the original signs of the cracking but having been told they appear to be spreading in my view removing parts of it might not be the best way to go as that may resolve the problem now but could it continue in areas not removed.
I have informed the customer that I would be unhappy to tile the floor if it is patch repaired .
Can only wait now and see what the contractor says after they have inspected.
Unfortunately they won't have a nice new floor in the kitchen when they move in middle of next month.
I will post what the outcome is when I know more.

 

[Mark jude]

Normally water mix smoothing compounds are prone to crack , all floors should be cleaned properly , any loose debris cleared then a primer needs to be applied as named by what ever 2 part smoothing compound you are using .
Two part compounds are a much better product and this is only ones I use , Mapei trade plan , arditex na are both superb compounds , if you are making up the floor thicker sharpe sand or granite dust chippings should be added and this will help when building floor depth required . Instarmac also have some super products to