Self-levelling floor compounds provide an easy way to achieve a clean, level floor over old concrete, gypsum or portland sub-floors and some wood substrate floors. Before you apply a self-levelling floor to a non-concrete floor you must verify that any glues used to install the floor are water resistant, or the floor compound will destroy the bond. For all types of sub-floors, careful cleaning is required before applying the self-levelling floor compound. The actual application process is easy.
Sweep the entire floor. Then vacuum as well. You do not want any dust or debris left on your sub-floor; this can interfere with the ability of your self-levelling floor to form a good bond.
Apply a mild concrete etching solution if your sub-floor is concrete. If your sub-floor is not concrete, skip to Step 4. Carefully follow the directions on the product you have chosen. Acid left on a floor for too long can weaken the entire concrete floor and cause problems with cracking and adhesion later.
Spray the concrete floor with water from a garden hose to clean the acid off. Do not use a pressure washer. The force of water from a pressure washer will drive debris down into the concrete, and this will cause problems later. Allow ample time for the concrete floor to completely dry and the added moisture from the washing to dissipate in the air.
Mix your self-levelling floor compound in a bucket. Carefully follow the instructions on the product you have chosen. Some compounds are mixed with water only; others require special liquid additives to prepare them. The information will be on the packaging of the compound.
Pour the self-levelling compound onto the floor and use a squeegee to spread it over your sub-floor. A good rule of thumb to remember is that you only want about an 1/8" of the compound on the floor unless there is a dip or rise in the subfloor. For both of these instances, leave about a 1/4" of compound on the floor. As it levels, it will smooth into the flat areas.
Before you apply your self-levelling compound, take a few minutes to plan the direction you will take to do it. You don't want to "paint yourself in a corner" and wind up missing a portion of the floor or having to walk across the floor before it is cured. It sounds like common sense, but you also have to take into account how you will access more compound while applying it, should you run out, without letting what is put down set or what is premixed harden in a bucket. It is worth a few minutes of planning to figure this out to make the job go smoothly.
Make sure that the area you are working in is adequately ventilated. Not only are the chemicals present in any self-levelling floor compound potentially hazardous, but they will generate heat as they cure. Too much heat and chemicals in too airless a place can cause headache, dizziness or difficulty in breathing.