How to Blacktop a Driveway

Prepping the Driveway

Examine your driveway condition. Blacktop patching material can't solve every problem. Take a look at damaged areas before deciding how to progress: For depressions, thin cracks, and alligator cracks (cracks in a scaled pattern), repair them yourself as described below. If the damage covers large areas of the driveway, or if there are long cracks more than ¼" (6mm) wide, the only permanent solution is to hire a contractor to remove and replace the driveway. Also consider this for any asphalt driveway approaching 20 years old. Hiring a contractor to overlay the driveway with more blacktop is cheaper then replacement, but it is not recommended for driveways with drainage problems, or with large areas of alligator cracks.

Remove dirt and debris from the driveway. Use a leaf blower, compressed air blower with nozzle wand, or broom to clear away dirt, dust, and loose stones.

Trim the grass and weeds away from the edges of the driveway. If there is heavy weed growth, you may want to spray the vegetation with a long-lasting herbicide at least two weeks prior to starting the project. This will ensure the plants do not grow back. If grass or weeds are growing in cracks in the driveway, scrape them out with a screwdriver, then sweep the cracks with a whisk broom.

Scrub away any grease spots. Apply a heavy degreasing detergent and scrub with a sturdy wire-bristled brush. Avoid using solvent-based cleaners. They will leave unseen residue behind, which will have an adverse effect on the blacktop's adhesion.

Fill in the subsurface for deep holes. If an area of the driveway has broken off and revealed the subsurface underneath, fill the hole with dirt, gravel, or sand until it is level with the rest of the subsurface.

Filling Potholes and Deep Depressions

Wear protective clothing. Put on gloves, protective eyewear, and long sleeves and trousers before handling the blacktop. Check the product label for safety instructions.

Select a cold pour pothole patching material. Blacktop (asphalt) repair products come in a couple different varieties. The asphalt pothole patching material is the best choice for missing chunks of asphalt (potholes), and for depressions deeper than 2 inches (5 cm). You'll want a cold pour product for home repairs, since hot pour products require specialized machines.

Cut the hole to form straight edges. You can skip this step to save on labor, but the patching material will create a stronger, longer-lasting bond in a hole with vertical edges. An asphalt saw is the easiest way to achieve this, but you can use a hammer and chisel to break the edges of the hole instead. Clean away any dust and broken asphalt created by this process.

Pour on a layer of patching material. Pour it directly from the bag until you've added a ½ to 1" (1.25 to 2.5 cm) layer throughout the hole. For larger holes, spread the material around with a rake or shovel. It's not a problem if the material spills over onto the surrounding surface.

Tamp it down. Push the patching material down with a pothole tamper, vibrating plater, lawn roller, or any other heavy object. For a large area, you can oil a piece of plywood to prevent sticking, then place it oiled side down over the patch. Drive over the plywood to compact the material underneath.

Repeat until the hole is filled. Continue applying and compacting layers of patching material until the hole is level with the surrounding driveway. Using layers no thicker than 1" (2.5cm) will help prevent air spaces from forming and weakening the repair.

Seal the area when conditions allow. Applying an asphalt sealer over the repair will make it more durable. However, you can only apply the sealer in certain conditions: Wait at least 4 hours for the patch to cure, or as directed on the label instructions. Wait until the weather is at least 60ºF (16ºC), the driveway is dry, and you don't expect rain. If the sealer gets wet before it cures, some of the patching material may be washed away.

Filling Cracks and Minor Depressions

Follow safety instructions. Check all product labels for safety instructions before you begin. Gloves, work clothing, and protective eyewear are all recommended.

Fill small cracks with asphalt crack filler. If you have single cracks less than ¼" (6mm) wide, use asphalt crack filler. Check the label for application instructions or apply as follows: Shake the bottle to mix the product evenly. Cut off the top of the nozzle so the opening is narrower than the crack. (If there is no nozzle, load the product into an asphalt caulk gun instead.) Squeeze the filler directly into the crack until it is flush with the driveway. Let dry for 24 hours. If the filler has sunk below the driveway surface level, apply an additional coat. Wait at least 24 hours after the final coat before walking or driving over the repair.

Buy alligator asphalt patch for more serious cracks. This material is intended for "alligator scale" or "spiderweb" crack patterns, single cracks wider than ¼" (6mm), and small depressions shallower than 2" (5cm). If the alligator cracks are severe, chunks of the asphalt may be fully separated from the driveway. You may achieve a stronger repair if you remove these entirely, then refill the hole using the pothole method above.

Spread the alligator patching material with an asphalt squeegee. Pour a little of the material onto the center of the damage. Spread it out with an asphalt squeegee (or an asphalt brush) until the damage is covered with ⅛ to ¼" (3 to 6 mm) of material. Check the label instructions first. Some products may need to be mixed in a bucket before application.

Repeat until level. Spread on additional alligator patching material until the cracked area or depression is level with its surroundings. For a more even transition, squeegee out a thin layer one or two feet (0.3 to 0.6m) in each direction.

Let dry. The material will harden over the course of a few hours, depending on climate and depth of the repair.

Repeat if needed. Thick repairs may crack slightly over the course of a few days. Apply an additional thin coat if this happens.

Allow 24 hours for the blacktop to dry and cure before parking or walking on the driveway.