How to Seal Concrete Floors

Properly sealing concrete floors can help protect your home from moisture issues, and can make floors look and feel better.

A concrete floor in a garage that needs to be sealed. A brick column is in the middle of the room, and wooden shelves line the walls.
Before you get started, keep in mind that a project of this nature can be a lot to tackle, and you may need expert help.

Learn how to seal your concrete floors with tips and tricks from the experts.

The Moisture Test and When to Call in an Expert

Unsure if you have moisture problems? There are two simple tests you can perform to check if you have water exposure.

Test #1: Lay a rubber mat down on the floor and check back in 24 hours. If the bottom of the mat has moisture on it, the floor is not ready to be painted.

Test #2: Tape a piece of clear plastic on the floor, typically a 45 cm x 45 cm (18" x 18") sheet of 3-mil plastic with duct tape along the edges to seal. Check back in 24 hours. If moisture is visibly present after conducting the test, contact a professional painter to determine the right path for painting.

Just because you don’t see any water in one part of the floor, that doesn’t mean there isn’t a moisture issue elsewhere in the room. If you suspect any moisture problems, or you’re unsure about any part of this process, it’s best to contact a professional painting contractor for help.
A homeowner tests a concrete floor by pouring a few drops of water from a small glass onto the floor. A homeowner tests a concrete floor by pouring a few drops of water from a small glass onto the floor.

Step #1: Determine whether your floors are bare concrete or previously coated.

Do the water drop test to check if your floors are bare concrete or have been previously sealed or painted:

  • Pour a dime-sized drop of water on the floor.
  • Wait 60 seconds.
  • If it beads up and doesn’t soak into the floor, the surface has been previously sealed or painted.
  • If the water soaks into the floor after a minute, it is bare concrete.

If you determine that your floor has been previously painted or sealed and you’d like to redo it, you may have to use a grinding machine to smooth out the surface before sealing. Try applying sealant to a small patch of the existing coating on a clean and dull floor. If there is no adverse effect, it can likely be re-coated. If the sealant doesn’t adhere, it may be necessary to grind the floor.


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Helpful Tip

• Since concrete grinders are expensive, renting one makes sense. Visit your local Benjamin Moore® retailer for advice on rentals.

• Consider consulting a professional if you determine that your floors have already been painted or sealed and you’d like to redo them.
A homeowner sweeps dust and dirt from a concrete floor using a green broom. A homeowner sweeps dust and dirt from a concrete floor using a green broom.

Step #2: Clean and prep your space

Start by removing all furniture and rugs from the area you’re sealing. Thoroughly clean the entire floor by sweeping and mopping the space, and use a damp cloth with warm soapy water in a bucket to remove any difficult spots. Rinse well with clean water and allow the floor to dry for 24 hours.

A homeowner applies sealer to a floor using a paintbrush. A homeowner applies sealer to a floor using a paintbrush.

Step #3: Cut in your floor

Using a paintbrush, establish the borders of your project by applying the sealant to the floor around the edges of the room.

A homeowner applies sealer to a floor using a paint roller. A green painting tray is on the floor. A homeowner applies sealer to a floor using a paint roller. A green painting tray is on the floor.

Step #4: Seal the floor

Switch to a roller and paint tray. Roll the sealant onto the floor, working toward the exit of the room, so as to not paint yourself in. Allow the sealant to dry (check the can for recoat time) before applying a second coat. Roll the second coat in the opposite direction of, or at a right angle to, the first coat.

A concrete floor that has been sealed. A brick column is in the middle of the room. A concrete floor that has been sealed. A brick column is in the middle of the room.

Step #5: Allow the floor to dry completely

Check the back of the can to find the dry time of your sealant. Dry time is very important when sealing concrete floors, as you’ll want to be sure the sealant has fully dried before you walk on or return furniture to your concrete floor.



Visit your locally owned Benjamin Moore paint store for help with all your painting needs. Find more tips in our How-To section.
Left side with dark blue paint on wall and roller, right side with red paint on wall and roller.

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