If there are failures and slopes in the floor, it must be aligned before laying the finish coating. Otherwise it will be fed and creaked. To ensure a smooth surface, heat and sound insulation, you need to use a self-leveling screed. The mixture must be selected depending on which the finish coating will be laid, where they can be both lightweight and weighted compositions.
To repair the floor and construction, you will need a mortar cement-sand. You can order a mortar cement sandy according to the link. Prices are inexpensive.
The level must be set “zero” markers with a height of 1.5 m from the floor. Horizontal line markers are connected, checked by level. Such measurements from the line to the floor should be carried out on each wall in several places. Then, on all walls, with the minimum thickness of the layer at this level, you need to hold a horizontal line.
The base must be cleaned with a vacuum cleaner from dirt and dust, remove traces of putty, paints, fatty and oil spots. To improve the clutch of the screed with the base floor and the bottom surface of the walls is covered with primer. The lower part of all partitions is closed by rubberoid or other waterproofing.
To rolling the rule you need to install the rails that should be aligned by the marked line. Prepared solution must be poured between beacons. After drying the solution you can carry out a grout.