How to Seal a Driveway

A driveway is a big homeowner investment in curb appeal, as well as dollars spent. When it’s stained, cracking or crumbling, it can really bring down the appeal of your home’s exterior. However, you can prolong a driveway’s lifespan and delay spending a fortune on a new one down the road by taking steps to protect it. Sealing your driveway protects it from the ravages of age and the elements.

Step 1: Determine Driveway Conditions

Inspect your driveway for cracks or other damage and fix the problems before you seal your driveway. Cracks, if left unattended, can eventually grow and cause the driveway to crumble. Whether you have an asphalt or concrete driveway, the more proactive you are at repairing cracks and then sealing the driveway, the longer your driveway will last without the need for expensive replacement or resurfacing. Plan the project so that you have at least two to three days of sunny or otherwise rain-free weather in which to work and let the sealant set. Because sealants provide protection against water infiltrating the surface, they won’t be as effective if water contaminates them.

Step 2: Prepare the Driveway for Repair / Sealing

Remove any weeds that may be growing in driveway cracks. Sealing a driveway requires a clean surface. For concrete driveways, use a hammer and mason’s chisel to chip away at any soft or crumbled concrete in and around cracks or crumbling areas. Concrete cracks must be chiseled so that the crack is wider below the surface than on the top. Clean with a stiff wire brush to dislodge and remove all loose particles from the edges of small holes and any large cracks. Then use a stiff push broom to remove dirt and debris from the driveway. You can also blast away loose material with water from a garden hose, using as much pressure as possible. Or, consider renting a power washer. Work from the center out to the sides or from one side to another. Start uphill, too, so the dirt won’t wash back onto the cleaned area. Hose the driveway until it’s completely wet and then add a driveway cleaner such as Sakrete® Concrete/Asphalt Cleaner. Use a stiff brush or push broom to work the cleaner into the surface. Then hose the driveway again until the water runoff is clear. Let it dry completely.

Use a shop vacuum to remove any remaining dirt from the cracks to be filled. These must be very clean and dry before filling.

Step 3: Repair Damage

Asphalt Driveway

Use a driveway filler/sealer with rubberized asphalt emulsion in pourable squeeze bottles that fill cracks up to 1/8″ wide for best results on asphalt driveways. Squeeze the liquid into the crack, filling the crack completely.

For cracks up to 1/2″, use crack filler packaged in no-mess cartridges for a caulking gun or in pourable squeeze bottles. Squeeze the caulking gun trigger steadily as you pull the tip along the crack. If using pourable filler, fill the crack and smooth away excess with a putty knife. Be sure to keep the filler in the crack, not on the driveway surface.

For cracks 1/2″ to 2″ wide, fill the crack with non-porous foam backer rod material before applying crack filler. For potholes or cracks wider than 2″, you’ll need to do a little more repairing. Shovel packaged cold-patch blacktop into the well-cleaned hole, and then use a level-head rake to level the patch. Use a cold chisel and a hand-drilling hammer to undercut the edges so the hole is wider at the bottom than it is at the driveway surface. This will lock in the patch once it has been compacted. Press down the material as best as you can with a tamper or the end of a 2′ x 4′ board, adding more material as you go, until the hole is slightly overfilled. Then place a piece of scrap plywood over the patch and drive your car back and forth across it to further compact it.

To fill hairline concrete cracks, you can usually use a patching compound to make the repair. First apply a concrete bonding adhesive or primer/additive to create the best bond possible between the old surface and the patching material. Use an old or inexpensive paintbrush to work the liquid into the surface. Wash the brush immediately after use with soap and water or discard it.

Use a putty knife or trowel to apply a vinyl patching compound in multiple layers as directed by the manufacturer. Mix only the amount of patching you’ll need for each layer. Press it firmly to force the initial layer into all nooks and crannies and allow drying time between layers.

You can also patch thin cracks with a cement mixture. In a small bucket, mix one part cement and three parts sand with enough water to make a stiff paste. In a separate container, mix a small amount of cement with more water—enough to make a cement “paint.”

If you can, paint the inside of the crack with the thinner cement mixture. This will act like a primer. Then take the paste mixture and pack it firmly into the crack with a putty knife or trowel. Level the mixture with a straight-edged concrete-finishing trowel. Let the patch sit undisturbed for about an hour, then go over the entire surface with a float or trowel in a circular motion, blending it well with the surrounding surface.

To patch large cracks (more than 1/8″ wide and 1/2″ deep), use foam backer rods. Sold in a variety of lengths and diameters, foam backer rods are great for supporting a patch and preventing it from sinking into any cracks as it dries and ages. Use a putty knife to force the flexible rod into the crack, placing it about 1/4″ below the surface. Now you can patch the area as you would with a small crack. After smoothing the patch with a trowel, let it set for a couple of hours. Then cover it with a sheet of plastic, weighing the plastic down at the edges with bricks or rocks. Keep the area covered for an entire week, making sure to mist it with a little water each day to keep it slightly moist.

Step 4: Apply Sealant

Asphalt Driveway

Once the cracks are filled or other repairs have been made, it’s time to seal the driveway. For asphalt driveways, use a water-based acrylic filler / sealer. You can expect to cover 300 to 500 square feet per five gallons of sealer. Be sure that your patches have cured completely before you apply sealant.

There are two types of driveway sealers: a standard mixable type and a gel. Standard sealers require that you mix them every few minutes to keep the heavy solids from settling. The gel type needs no stirring. If you’re not sure which one to choose, ask an expert at your local True Value^® hardware store. Before you start, mask adjoining areas and mist the driveway with water. Then pour a 1′-wide ribbon of sealant across the driveway. Push and pull the sealant with the squeegee side of a brush applicator to spread it until you’ve covered an area that’s about 3′ or 4′ wide. Repeat this process until you’ve covered the entire driveway. You can also go over the surface with a paint roller on an extension pole to even out the coverage.

Using the brush side of the applicator, pull the sealant toward you and apply enough pressure to remove all excess sealant. Continue down the driveway. Two thin coats are better than one thick coat. Allow the first coat to dry between four to 12 hours before applying the second. Block the end of the driveway to keep cars off until it is completely dry—at least 24 to 36 hours.

For a concrete driveway, purchase a quality waterproof concrete or masonry sealer. Estimate the amount you will need, using the same method used for asphalt sealer above. Read the manufacturer’s instructions carefully. Apply the sealer using a roller applicator and extension pole, starting at the top of the driveway, working your way across in 3′ to 4′ sections. Apply at least two thin, even coats, leaving time in between for the coats to dry, for a duration specified by the manufacturer. Don’t use the driveway for at least 24 hours after applying the last coat.

That’s it! You’re done. Your driveway has been repaired, sealed and renewed.

Project Shopping List

Here’s what you’ll need to complete this project successfully.

• Hammer
• Masonry chisel
• Stiff wire brush
• Stiff push broom
• Garden hose
• Power washer (optional)
• Environmentally safe detergent
• Safety glasses
• Diluted driveway cleaner
• Old clothing
• Kneepads
• Shop vacuum
• Asphalt sealant
• Caulk gun
• Spray bottle
• Putty knife
• Non-porous foam backer rod material
• Cold-patch blacktop
• Level-head rake
• Cold chisel
• Hand-drilling hammer
• Tamper
• 2×4 wood board
• Scrap plywood
• Concrete patching compound
• Concrete bonding adhesive or primer/additive
• Paintbrush
• Dust mask
• Float
• Trowel
• Vinyl patching compound
• Cement
• Straight-edged concrete-finishing trowel
• Bricks or rocks (for holding the plastic in place)
• Water-based acrylic filler/sealer
• Brush applicator w/squeegee side
• Paint roller
• Extension pole
• Silica sand additive (optional)
• Waterproof masonry sealer
• Traffic cones
• Driveway sealer