Before you pour give the existing slab a thorough cleaning with a degreaser to remove any contaminants that might interfere with achieving a strong bond.
Level concrete slab before flooring.
When you re finished spread some concrete leveler primer over the floor and let it dry until it has a tacky finish.
To level concrete floors start by cleaning the floor and filling in any cracks or holes with concrete filler and sealer.
To resurface an uneven concrete slab begin by laying a long straight 2x4 wooden rail across the concrete slab floor with one end positioned on the high point in the room.
It spreads across uneven slabs filling in low spots as it creates a new level surface.
Then go over any particularly high spots with a concrete grinder so they re level with the rest of the floor.
Fill any low spots with a cementitious leveling compound following the manufacturer s directions and allow it to dry before proceeding.
Typically the floor must be level and uniform within 3 16 inch every 10 feet.
High spots may require grinding the concrete to achieve a level surface.