Self Levelling Compound - Cracks

[bluefin]

Hi everyone - first time poster looking for some advice on some self-levelling issues I'm having. Room is approximately 9msq, original floor is concrete and was quite uneven for the laminate I wanted. To fix it, I had someone round to put some compound down about 9 months ago. The compound itself is still sound but full of air holes and lots of it seeped out under the skirts/door etc and therefore was still not level enough for laminate - very uneven along the borders and dipped in the middle. Since then, starting about a month ago, I've put down two separate pours - Mapei 1210 - and used primer G. and left about 10 days between my pours. Recently I noticed some cracks as shown in the pics. The areas around them (maybe 10cm radius of the crack line) sounds a little hollow compared to the rest of the floor but the compound itself is solid and not chalky. I poured to the maximum allowable with Mapei 1210 - 1 cm - but fear it maybe went a mm or two over in the end. I was very strict with the prep - primer first, clean bucket, exactly 4l water as recommended and spike rolled after. My intention was to switch to a fibrous, more flexible option for the final pour - Mapei Ultraplan 3240 - and pour so there is a minimum 3mm cover over the entire area. Some bits are still probably 1cm off this but the 3240 has a much better max depth so it should be OK. Obviously I'm a bit concerned about the hollow sounding bits - I'm wary of trying to take up the hollow patches (only about 5% of the floor overall) and damaging the bits that are fine but equally just want to get it right. Does anyone have any advice or thoughts? Thanks very much in advance.

 

[^woody^]

Cracking typically relates to drying too fast or laying too thick. Sometimes it can be due to the poor adhesion from lack of prep or priming.

It's difficult to get the mix wrong to cause any cracking.

It wont tend to be a problem once the flooring is down