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How To Seal a Garage Floor

Updated
Seal and protect your concrete floor with our handy guide.

Garage floors get a lot of punishment. Oil, paint, tire burns, mold, and mildew all attack the garage floor and leave nasty stains. Concrete is porous, so it also soaks up moisture, which could lead to extensive damage to your garage floor.

We show you how to seal a garage floor to protect it against damage and keep it looking great for years to come.


How To Seal a Garage Floor

Before we get started on how you seal the floor, we need to prepare the surface, which means removing all those unsightly stains and filling cracks. For that, we will need some tools and materials.

What You Need

  • Pressure washer.
  • Vacuum cleaner.
  • Broom.
  • Sawdust.
  • Paintbrush.
  • Paint roller frame and covers.
  • Extension pole.
  • Concrete cleaner.
  • Epoxy paste.
  • Concrete etcher.
  • Epoxy resin floor kit.
  • Concrete paint.
  • Trisodium Phosphate (TSP).

Prepping the Floor

You will need to remove any oil, rust, and other stains that make the garage floor look unsightly.

Remove Oil Stains

  1. Cover the oil with sawdust to draw up any excess fluid. Sawdust has super absorbent qualities. Leave it down for at least 24 hours.
  2. Grab the broom and sweep away the sawdust.
  3. Pour the concrete cleaning agent on the stain and leave it to sit for an hour. You can use bicarbonate of soda or vinegar if you don’t have a concrete cleaner.
  4. Use the concrete cleaner to scrub the entire garage floor with the broom.
  5. Now pour boiling water on the stain and scrub vigorously with the broom.
  6. For really stubborn stains, your pressure washer set at 1,200 PSI (pounds per square inch) should do the trick.

Remove Rust Stains

Pour an ounce of trisodium phosphate (TSP) into a bucket, add a gallon of hot water, and mix. Pour the solution onto the rust stain on the floor and start scrubbing with the broom. Allow the TSP to soak into the concrete for 20 minutes and then rinse thoroughly.

Repair Cracks

Small cracks can leave your floor looking unsightly, so grab the epoxy paste and start filling them. Remove excess epoxy so that the surface is smooth with the garage floor.

Leave the paste to set and then grab some sandpaper and sand the surface smooth.

Remove All Dust

Once you have successfully removed all the unsightly stains, you will need to get rid of debris and dust. Most of the loose grit on the floor’s surface would have been removed during the scrubbing process, but before laying down the sealer, it’s worth a final check.

Use the broom to sweep away obvious debris and then grab the vacuum cleaner to get at the microscopic particles.

It’s Time To Prepare the Floor

Before proceeding any further, there are a couple of checks you need to make to determine the state of your concrete floor.

Check for Moisture

Did you notice a lot of mold or mildew staining on the floor while you were cleaning it? If you did, it could be a sign of excess moisture in the concrete. To check, cut a square of plastic sheeting and tape all the edges to the floor, ensure there are no gaps.

All you have to do now is wait. After 24 hours, check the plastic, and if you see moisture collecting on the underside of the plastic, you have a moisture problem that will stop the sealer from adhering. Plus, you risk trapping in all that water once your epoxy floor kit hardens.

You can buy breathable epoxy that lets the moisture evaporate, or you can put down a good vapor barrier before applying the primer.

Check for Old Sealant

Your garage floor may have been sealed previously. Luckily, there is an easy way to check. Pour water on the concrete and watch closely to see if the liquid absorbs. If it does, you are good to go with the sealer, but if you notice the water start to bead on the surface of the floor, you may need to apply a concrete etcher.

How To Etch the Floor

Apply the concrete etcher according to the manufacturer’s instructions. If the etcher fizzes, you know it is doing its job and breaking down the old sealer. Leave the floor to dry for 24 hours, and the following day, grab the broom and sweep away any excess dust.

Let’s Seal the Floor

Sealing the floor prevents staining, oil damage, moisture and protects against mold and mildew. A layer of sealer also acts as a primer if you want to paint the floor later. It helps the paint adhere better, making it less likely to peel, flake, or chip.

For the best results, use a water-based epoxy floor kit or a solvent-thinned epoxy. Grab your paintbrush and start by working around the edges of the floor. Make sure you get a liberal coating into all the nooks and crannies.

For the center section of the floor, grab the roller, making sure it is lint-free, solvent, and water-resistant, and it has a medium nap (the hollow cylinder in the center of the roller that slips onto the handle).

Apply a liberal coating of the sealant and make sure you get it down as smooth as possible. Work from the furthest wall from the entrance, and make your way towards the door. This prevents you from getting painted into a corner.

If you want to paint the floor, allow 24 to 48 hours for the epoxy sealant to cure.

Tips for Sealing a Garage Floor

What is it that the pros do that leaves a super-professional finish? We share some hints and tips to help you achieve the best results.

Follow the Instructions

Sounds simple enough, right? You’d be amazed how many people disregard instructions. They adopt the attitude “How hard can it be?” and dive straight in. The problem with that approach is you make critical errors that could affect the longevity of your concrete sealer.

Use An Extension Pole

Sealing a concrete floor can be backbreaking work. A roller extension pole enables you to get the sealer down without having to stoop. It is one of the most useful tools to own when sealing floors.

Get the Right Roller

Invest in a quality roller cover. Go lint-free and solvent and moisture resistant for the best results. Also, don’t use a roller cover with a nap wider than about 0.25 inches because you risk applying the sealer in thick layers.

Another great tip is to run the roller over duct tape to remove excess lint from the surface.

Have a Wet Edge

Try not to stretch the sealer, so it goes on too thin, as this creates a dry edge. When you apply some products, the roller or brush marks show between each pass, leaving lap lines. Leave the roller wet and run over the previous pass by an inch or two to allow them to merge.

Check the Weather

Keep an eye on the temperatures when laying down the sealer. Most film-forming sealers should be applied when the thermometer reads between 50 and 80 degrees Fahrenheit. The sealer will start to cure and leave bubbles on the surface if it is too hot due to the rapid drying process.

Avoid humidity of 85 percent or higher, and don’t apply the sealer within 24 hours of rainfall. If you are using a penetrating sealer, you can apply them in temperatures of between 40 and 90 degrees Fahrenheit.

Use a Sprayer

Sprayers speed up the process dramatically, and they also apply in even coats. Use a paint sprayer with a cone-shaped nozzle because it helps distribute the sealer better and avoids dark stripes and overlaps.

Work in a circular motion to lay the sealer down evenly, and if you are using a pump-sprayer, ensure that the pressure levels are maintained, so the sealer doesn’t look patchy.

Paint After Sealing

Painting your garage floor after sealing is a great way to cover up a multitude of sins. If the sealer finish is patchy or uneven, if the floor still has stains that just won’t budge, or if you simply want to brighten up the space, painting is a great option.

Sealer is an excellent primer because it helps the paint to adhere and reduces peeling, cracking, and chipping.

If you are painting the floor, wait 24 hours for the sealer to cure and read the manufacturer’s instructions for guidance on paint drying times.


Headshot of Mark Weir

About the Author

Mark Weir

Mark spent 24 years working in real estate, so he knows his way around a home. He also worked with contractors and experts, advising them on issues of planning, investments, and renovations. Mark is no stranger to hands-on experience, having renovated his own home and many properties for resale. He likes nothing better than seeing a project through to completion.