How to Grind & Level Concrete for Garage Doors

Remove items from the garage floor where you are going to grind concrete. Grinding concrete creates a lot of dust, so cover items that you don’t want to get dirty. Allow adequate ventilation as you work.

Move a 4-foot, or longer, carpenter’s level across the surface of the concrete floor to identify where the high spots are. Pay particular attention to the high spots under the garage door. Mark the high spots with chalk.

Tip the concrete grinding machine backwards to expose the grinding mechanism. Attach the grinding stone attachments to each of the gear assemblies following manufacturer’s directions for the grinding machine you rented. Fasten the grinding stones to the machine by tapping their hardwood locking wedges in place with a hammer. Set the grinder upright again.

Attach dust receptacles to the grinding machine if it has them, following directions for that particular model. If the machine attaches to a vacuum, use only an industrial-strength shop vacuum as the dust-removal system.

Release the mechanism that allows the transport wheels to retract into the machine. Do not operate the machine with the transport wheels extended.

Connect the grinder to the electrical outlet, if it’s an electric model, and turn the power on. Start the engine if the model is gasoline or propane powered.

Apply a bit of downward pressure to the handles of the grinder to lift it slightly from the concrete surface. This makes it easier for the machine to come up to speed before you engage the grinding stones with the concrete.

Turn on the grinding stones. Release the pressure on the handles to fully engage the grinding mechanism onto the concrete. Move the machine back and forth across the area you need to level. Periodically turn off the grinders and check the levelness of the floor with the carpenter’s level.