A self-leveling overlay is a good way to repair a garage floor that's seen better days. It can cover old cracks, uneven spots and ugly stains. You can leave the new overlay as a plain color, or you can spruce up your garage floor with decorative engraving and colors.
Clean the garage floor surface. Remove all grease, wax, paint and whatever else might be on the floor.
Repair any cracks. Level any uneven patches in the flooring with concrete mix. Feather the edges to make the old floor as level as possible. Let the cement patches dry, according to product specifications.
Create metal or wooden dams all around the garage perimeter to hold the overlay. Depending on how thick you are pouring the overlay, they can be slightly taller.
Use duct tape to provide an additional barrier between the overlay and floor joints.
Apply primer to the floor. Use a brush, or spray it on. Leave no puddles. The primer needs a couple hours to dry-if you are applying the overlay to old cement, you need to apply two coats.
Mix the overlay into the water following manufacturer's directions exactly. Stir with a paddle attached to a drill.
Begin the pour. Once you start, don't stop. You must have at least two people working. One person keeps the overlay mixed, and one person pours.
Work from one corner to the other across the narrow width of the room. Pour the overlay material directly from the bucket in foot-wide strips. Allow the overlay to find its own level. Use the trowel to push overlay into tight corners.
Allow no more than 15 minutes between batches. When you finish the first strip across the room, start a second strip from the original side. Continue until you finish the entire garage floor.
Let the overlay air dry according to manufacturer's directions. Also, apply any finishes according to manufacturer's directions.
Clean your tools as soon as possible after you finish.