How to level concrete by 4mm around stubborn old tiles?

[nworb]

Hi,

I have old tiles on my concrete which can't be scraped up, a lifter would sooner dig up the concrete.

On the wood floor abutting this the previous owner has put hardboard underneath the laminate finish to get a level finish. This has since degraded/rotted.

The perimeter of concrete was not levelled because it was never tiled. I need about 4 - 5 mm build up there. This area is roughly 2 foot by 15 foot.

I guess plywood would be best for wood but for the concrete I expect I would need to be very sure I achieve a minimum of 4mm if using a cheapo sand-cement for it to retain its strength.

Are there any tips you can give me for mixing my own thin-set concrete here?

 

[PrenticeBoyofDerry]

Thing is 4mm of concrete will not bond to surface and over time crack and shale off.
I would suggest self-levelling but some self-levelling does not like to be left exposed and would need to be treated. Also you will need to find one that can deal with 4mm depths.

 

[nworb]

Thankyou PrenticeBoy.

I will be covering it so finish is not that crucial. I would like to put down 25mm of Celotex followed by 2x9mm OSB.

Also, when I said concrete I rather meant a cement-sand mix. I've seen this referred to as screed and dry mix both here and in Barry's Vol1. More importantly, I believe 4mm will be adequate with covering. As you say, over time it would crack, but I have a similar repair made in my yard that has held fast for years, although I was probably quite liberal in my addition of cement to that mix.