Concrete Floor not level

[StuFi]

Please can someone help! I need to level a concrete subfloor that has already been screed. Can I use concrete over the top? Or does it need to be SLC, and how thick can that be? The screed is coming away in some places round the edge of the room. I also need to make sure it is waterproof but now sure of where to start. Would be grateful for any tips / ideas.

 

[Kingfisher20]

Sounds like you need an "epoxy self-level membrane" floor kit. Kingfisher does one but plenty other manaufacturers also. Essentially this will work to level up 3 to 5mm and is waterproof - in fact is used mainly on old concrete floors to level up and seal damp patches. You need the primer and then the epoxy SL kit. Most manufacturers have a 2 part primer which you put down to create the "key" followed by the 2 part epoxy mixed with the SL powder.