Levelling a concrete floor for bathrooms and kitchens
A concrete floor which is out of true can be levelled using a self-levelling flooring compound so it is suitable for tiling. For the compound to form a smooth, even surface it should only be applied to a floor which is clean and free from dust, oil, grit or grease so you should first sweep the floor and then scrub it thoroughly (1). You may find you have to use a proprietary cleaner to remove stubborn greasy patches. The compound comes in powder form and you will have to mix it up according to the manufacturer’s instructions so it forms a runny paste
If you try covering the entire floor in one operation, it’s likely the compound will set into large pools which are difficult to join up. It’s better to work in small areas; you can delineate your working area by forming a bay using timber battens. Pour the compound onto the floor and then spread it out as evenly as possible using a steel float, any marks from the float will disappear quickly. The compound will set within a couple of hours. If you want extra thickness you can apply a second coat once the first is hard.