If the area is very large, use a long, straight 2 in × 4 in (5. 1 cm × 10. 2 cm) board and set your level on top of it. If the floor is uneven, lift up the board until it is level so you’ll know how much flooring compound you’ll need to even it out. Floors are rarely perfectly level. It’s okay if the angle is off by a fraction of an inch in either direction. Keep in mind that “flat” isn’t the same thing as “level. ” Minor defects may not be noticeable to the eye, but they will be to your level. [2] X Research source If you’re installing a new floor, make a note of where the foundation should be worn down or built up.
Sanding and grinding produces a lot of dust. Be sure to wear eye protection and a facemask or ventilator while wearing down uneven subflooring.
Fill cracks in concrete subfloor and make sure the filled areas are level before cleaning the subfloor. A thorough cleaning is also necessary to get the subflooring ready to accept the liquid bonding agent.
The bonding agent will create a chemical connection with the leveling compound to help it set up more securely and last longer. Wear gloves, waders, and old clothing when working with liquid bonding agents and leveling compound. Once these materials get on something, they can be nearly impossible to get off.
Stir vigorously to break up lumps, but work quickly. Some compounds begin to set up in a matter of minutes. An electric drill with a mixing paddle attachment will make mixing quicker and more efficient so you can spread the compound before it hardens.
Try not to over-apply the compound. In most cases, you’ll only need a layer between 1⁄4–1⁄2 inch (0. 64–1. 27 cm) thick to even out the worst imperfections. [8] X Research source To ensure that the finished floor turns out nice and flat, it’s best to go ahead and cover the entire surface. You’ll be able to chip away at what you don’t need later on. Be sure to work your way outward from the interior of the room, ending at the door. You don’t want to accidentally trap yourself in a corner!
Focus on lumps and contours where the different pools have dried separately and formed noticeable seams. [10] X Research source Pressing down too hard on the compound while it’s still wet could accidentally form depressions.
For the strongest, most durable finish possible, be prepared to let the compound dry overnight. Consider splitting your project up between 2 days—you can pour and smooth the compound on the first, then come back and touch it up on the second once it’s had a chance to set up.
Work your way from a low-grit sandpaper (around 24-40 grit) to a high-grit one (80-120 grit) to gradually smooth and blend the new surface. You may need to use a separate edge or corner sander to hit the areas closest to the walls.
If the floor is more than 3⁄16 inch (0. 48 cm) off level at any point, further compounding or sanding may be necessary.
Always take the time to gauge and level your foundation when beginning any new flooring project. As long as your subfloor is perfectly level, everything that goes on top of it will be, too. [13] X Research source
