It can take three days or longer, depending on the shape and size of the floor.
Cost
$1,000+
Costly rentals and equipment—you might want to leave this one to a pro.
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What you'll need:
TOOLS
Broom
Dustpan
Mohs pick
Scratch test kit
Concrete grinder
Dust extraction system and dust collector
Sprayer for applying chemicals
Microfiber mop
Trowel (optional)
Sponges (optional)
Float paddles (optional)
Hand grinder (optional)
Edging grinder (optional)
Roller (optional)
SUPPLIES
Dust mask
Safety goggles
Ear protection
Gloves
Knee pads
Concrete cleaner
Epoxy
Diamond grinding pads
Concrete densifier
Concrete sealer
Coloring agents (optional)
A glossy, polished concrete floor gives professional and private spaces a sleek, modern look that will last for decades. But if you’re wondering how to polish concrete floors yourself, you’ll need to take a deep look at your skills and the access you have to the specialized equipment needed for the size of your project. Achieving the perfect sheen is a complex process, but it might be doable for the (very) experienced DIYer.
Prepping to Polish Concrete
A lot of work goes into preparing concrete floors before you touch a machine to the concrete. You’ll have to grind the concrete, gradually using finer and finer grit until you’ve reached the level of gloss and shine you want. You’ll need diamond grinding pads (or discs) in several grits.
Equipment Preparation
Some of the prep work will depend on the type of machine you’re borrowing or renting. For example, if you rent a concrete grinder with a skirt and vacuum (dust collection system), you don’t need to rent a dust collection system or use your own vacuum to collect dust.
Using a concrete grinder takes some know-how and technique. If you’ve never used one before, practice in an inconspicuous area. You can cut too deeply into the floor if you go too slow but not deep enough if you go too fast.
Check the rotation on the head(s) of the grinder. Pads that rotate in the same direction cut more aggressively, so you may need to increase or decrease the rotation speed depending on the direction of the rotation.
You’ll also need to adjust the speed of the grinder according to the pad’s grit. Coarser grits require lower speeds to prevent the teeth from skipping over the concrete’s surface, whereas finer grits can run at higher speeds.
Safety and Cost
When using the concrete grinder or edge grinder, wear appropriate protective gear, including safety goggles, dust masks, ear protection, and gloves.
Lastly, consider that your final polished concrete floor cost will depend on several factors, such as the size and shape of the concrete, the concrete’s thickness, and the final look you’re trying to achieve.
Do a Hardness Test
Use a Mohs pick and scratch test kit, and following the manufacturer's directions, test the concrete to see where the concrete falls on the Mohs hardness scale. The concrete’s hardness determines the grit you need.
You’ll have the best success by buying all the grinding pads from the same manufacturer. Each manufacturer has its own system for rating the pads and the corresponding concrete hardness they work best on.
Clean the Concrete’s Surface
Photo: Artist and photographer from Poland / iStock / Getty Images Plus / Getty Images
Cleaning concrete is easier than polishing but no less crucial to the final result. Sweep or vacuum any dust, debris, or dirt from the concrete’s surface. Apply a concrete cleaner to remove adhesives or other chemical substances that could interfere with polishing. If the concrete has an existing coating, you’ll need to grind it off using the concrete grinder.
Seal Cracks and Holes
Using a trowel, sponges, float paddles, and epoxy, grout, or another semi-rigid filler, seal any cracks or holes. If left untreated, they can change the consistency of the final finish.
Grind the Entire Floor
Using the concrete grinder, attach the coarsest grit (lowest number) diamond grinding pad, and methodically grind the entire floor. You may need an edging grinder for square edges to complete the floor. If it's a smaller project, use a hand grinder instead of a walk-behind concrete grinder.
Change the grinding pads to those with a finer grit. For example, if you started with a 30- to 40-grit pad, go to an 80-grit on this pass. Do another pass over the entire floor with the finer grit pads.
After your second pass, get ready for a third. This time, use a finer grit yet again. For example, if you used a 40- and then an 80-grit pad (as described above), you can move on to a 150- to 200-grit grinding pad.
Spray on a Concrete Densifier
A densifier is a chemical hardener that contains silicate materials that react with the concrete to harden the floor, creating a protective top layer. It also reduces dust and improves the concrete’s strength. The product may be called a “densifer and hardener” or simply a densifier or hardener, but they all do the same thing.
Spray on the densifier while another person uses a microfiber mop to evenly spread it. The densifier may reach a point where it gels or pools, at which point, you can either spread it with the mop again to break the surface tension or add a small amount of water to that area to help the densifier penetrate the concrete.
Let the Densifier Dry
Allow the densifier to dry according to the manufacturer’s instructions. Densifiers generally take about 24 hours to dry, but environmental conditions may shorten or lengthen drying time.
Polish the Floor With Progressively Finer Grit Diamond Pads
By now, you know the drill. Using the concrete grinder, polish the floor with a 400-grit diamond grinding pad.
Apply Densifier, Coloring Agents, or Both (Optional)
This step will depend on the final look you want, and some people may choose to skip applying another layer of densifier altogether. You can:
Apply a final light densifier layer.
Apply a coloring agent, stain, or dye before applying a light densifier layer.
Some pros apply a light densifier layer to help lock in the color, while others don’t.
Change to a Finer Grit Pad(s)
Change the pads to an 800-grit, with the option of gradually using pads up to around 3,000-grit until you’ve reached the desired level of polish. You may not need to use the finer grinding pads, depending on the desired look and hardness of the concrete.
Polish the Entire Floor Again
Do another pass over the entire floor with the concrete grinder with the finest grit pads you’re going to use. This step is where you’ll create the glossy finish. You may need to repeat steps 10 and 11, using increasingly finer grit grinding pads.
There are many options when looking at how to seal concrete, from polyurethane to acrylic and epoxy sealers. Choose a sealer or stain guard based on where and how the floor will function. Use a sprayer and microfiber mop or roller to apply the sealer.
DIY vs. Hiring a Pro
Polishing concrete floors is a long and complicated process that requires costly equipment. Everything about concrete, from its hardness to the climate and whether it’s a new or old floor, affects the polishing process. (You’ll need to factor in concrete slab costs if you’re dealing with a new pour, too.) Unless you have experience polishing concrete floors, you’ll get the best results by contacting a local concrete pro. They can determine the right pad grits, densifier, and sealer to achieve your desired look.
Frequently Asked Questions
Yes, you can polish an old cement floor. However, be aware that the first pass with the concrete grinder may reveal a few surprises and imperfections. You may also have to contend with the consequences of previous floor coverings, such as tile or carpet, which can leave a pattern in the concrete. Old concrete is more likely to produce uneven results if you want to use a dye or other coloring.
Polished concrete gets its glass-like finish from several rounds of polishing, using increasingly finer grit diamond grinding pads. The concrete’s hardness will determine which grits you need to get your desired finish. The densifier and sealer also contribute to the look of the final floor, so either talk to a concrete pro (or hire one) to achieve the right concrete floor finish.
Stacey has written in the home improvement space for more than five years for sites like The Spruce and Bob Vila. She’s written about everything from plungers to pavers, but her home improvement heart lies in finding the perfect textiles. She loves combining deep product research with in-person testing to help homeowners find the perfect tool, appliance, or solution for common home problems.
Stacey has written in the home improvement space for more than five years for sites like The Spruce and Bob Vila. She’s written about everything from plungers to pavers, but her home improvement heart lies in finding the perfect textiles. She loves combining deep product research with in-person testing to help homeowners find the perfect tool, appliance, or solution for common home problems.
The homeowners guide to Concrete Driveways
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