How To Seal a Concrete Garage Floor

Fix it, maintain it, improve it. Your garage floor will last much longer if you take a few steps to keep it in good shape.

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Sealing your concrete garage floor is the best way to prevent damage from road salt and freezing temperatures. With so many concrete sealing/waterproofing products on the market, choosing the right product can be confusing.

Sealing a Garage Floor

It’s important to choose the right kind waterproof sealer for your garage floor. Here’s a brief guide to the pros and cons of each type of sealer you can use on concrete garage floors.

Types of garage floor sealers

Film-forming acrylic, epoxy and polyurethane products, like the increasingly popular polyaspartic coating, seal the concrete pores and impart a sheen or “wet-look” gloss to the entire garage floor for a really sharp look. These coatings are easy to clean, but they require more rigorous surface preparation. They’re also slippery, especially when wet.

Silane/siloxane formulas penetrate the concrete and react with minerals to form a “hydrophobic” surface that repels water, road salt and other deicing chemicals. The product won’t darken the concrete or look shiny, so your garage floor will still look like dull concrete

Why we chose silane/siloxane floor sealer

This garage is in Minnesota, so preventing damage from freezing water and road salt was critical. We didn’t care about gloss, but we wanted to avoid two steps that are required for many film-forming sealers: acid etching and roughening the surface. We chose MasonrySaver All-Purpose Heavy Duty Water Repellent, a water-based silane/siloxane. It took 5 gallons (about $30 per gallon) to seal the floor of this three-car garage.

Preparing the Garage Floor

Always start by cleaning the floor with a concrete cleaner and power washer. If you have oil stains, treat them before you power wash (see how to remove oil stains here). Then apply the sealer with a paint pad to get an even application and avoid puddles (Photo with step 2). After it dries, fill floor cracks with a polyurethane crack filler (Photo with step 3).

Project step-by-step (3)

Step 1

Apply the cleaner, scrub and power wash

Mask the walls with poly. Then use the power washer to apply concrete cleaner. Scrub garage floor with a push broom. Then rinse with high pressure and a 40-degree nozzle. Squeegee and let dry.

Caution:  To avoid electrical shock or carbon monoxide poisoning, always locate your power washer in an open area outside the garage (as demonstrated in photo above).

FH17ONO_582_06_033 power wash garage floorFamily Handyman

Step 2

Apply garage floor sealer and spread onto garage floor

Dip the paint pad into the garage floor sealer of your choice (we chose silane/siloxane) and spread it evenly across the garage floor to avoid puddling. Let the product soak in and dry.

FH17ONO_582_06_056 paint pad to clean garage floorTMB Studio

Step 3

Force filler into the cracks

To seal concrete cracks, you’ll have to get a caulk gun and apply filler directly into the cracks. Cut a small opening in the tube tip (we used urethane caulk). Then hold the caulk gun perpendicular to the floor, pressing the tip into the crack. Squeeze the trigger and force the crack filler deep into the crack.

FH17ONO_582_06_036 caulk in garage floor cracksFamily Handyman