Mother Nature is tough on asphalt. Sunlight breaks down the surface, creating pits and cracks. Then water seeps in, expands the cracks and erodes the gravel base below. Left alone, an asphalt driveway becomes a crumbling eyesore in about 15 years. But with a little maintenance, you can double the life of your driveway and save thousands in replacement costs.
Most driveways are big and conspicuous. And a long stretch of gray, cracking asphalt can give a home a scruffy look, no matter how handsome the rest of the property is. So a fresh coat of shiny black sealer isn't just protection against expensive driveway damage—it's a face-lift for your home and yard.
You can keep your asphalt in tip-top shape by following the three steps we show here. Asphalt maintenance doesn't require special skills, and you'll only need a few inexpensive tools. You can get everything you need at home centers and hardware stores. However, as with exterior painting, high-quality results hinge on some sweat and careful prep work. Expect to spend about six to eight hours completing the job. To fill cracks and seal coat an average driveway (750 sq. ft.), you'll spend $100 to $150 on materials. That's about half what a pro would charge.
Maintaining the asphalt skin is the best thing you can do to preserve your driveway. The asphalt layer serves primarily as a protective skin over the gravel base. The weight of your car is supported by the base, not the asphalt. If too much water gets through, the base erodes, causing additional cracking, potholes and total asphalt breakup.
The best way to keep the asphalt skin intact is to fill cracks, ideally every spring. Buy the high-quality pouring type filler. Read the labels. Our experts recommend the ones containing rubber compounds. They typically handle cracks from 1/8 in. to 1/2 in. wide. For smaller cracks, small tubes of filler in a caulking gun are easier to use. For larger cracks, 1/2 to 3/4 in. wide, buy an extra thick filler that you spread with a trowel, or tamp in asphalt patching material.
Fillers adhere to the sides of cracks, so your first task is to clean out the dirt and old, loose filler 1/2 in. to 1 in. deep. This is time-consuming. Use a screwdriver or a 5-in-1 tool shown in Photo 2) for the packed areas. Go deeper if weeds have taken hold. If you don't get all their roots, they'll grow right up through the new filler. Tip: A week before you begin this project, apply a nonselective herbicide to kill roots. Clean the crack edges (Photo 1). You can use a pressure washer or a garden hose, but then let the driveway dry for at least a day before filling.
Fillers need at least 24 hours to dry, so don't fill cracks when rain is in the forecast. The filling technique varies with the product, so check the directions. With most products, you can simply pour the filler into cracks up to 1/4 in. wide. For wider cracks, stuff in backer rod first (Photo 2). Backer rod is available in several thicknesses at home centers at a low cost.
Neatness counts when you're filling cracks (Photo 3). The jet-black filler contrasts with the gray asphalt and can look bad if you overfill or smear it.
Cracks that form a spider web pattern in a small area usually indicate that the base has softened. Water will settle in this spot and make the problem worse. Fillers will help for a while, but sooner or later you'll have to cut out and patch the cracked area. Cut the asphalt using a diamond blade in your circular saw (Photo 4). Then repack the gravel base by pounding it with a 6-ft. 4x4 or a hand tamper. Fill the cutout and pack with a 4x4 or hand tamper (Photo 5).
You can buy asphalt patching material at home centers and hardware stores, but it isn't nearly as durable as regular hot asphalt. For better performance, seal coat the patch after about six months. And for areas larger than a few square feet, we recommend that you hire a pro. (See “Talk to a Pro,” below.)
Asphalt edges are especially prone to cracking because the base erodes at edges more easily. Grass invades the cracks and increases erosion. So every other year, grab a shovel or lawn edger and cut back the grass (Photo 6). Then clean out and fill the cracks.
The purpose of a seal coat is to protect the asphalt against sun and water and to fill small cracks. It also dresses up the asphalt by covering fillers and patches. You don't need to do it every year. In fact, seal coat will peel if there are too many layers, and you'll permanently ruin the appearance of the driveway.
Home centers carry several sealers. Buy the best one (the most expensive!), especially if you're sealing your driveway for the first time. A better sealer means better long-term adhesion. Adhesion is vital, because you'll apply more coats in future years, and each fresh coat is only as good as the coat beneath it.
To ensure good sealer adhesion, the driveway must be clean and dry. Fill cracks and edge the driveway at least a week in advance. Scrub with a stiff broom. Then sweep or blow debris off with a leaf blower. You can use a garden hose or a pressure washer, but you'll have to wait for it to dry.
Sealer won't stick to oily spots left by a drippy car. First scrape off the oily gunk with a putty knife. Then apply a detergent (such as dishwashing liquid) or buy the sealer manufacturer's cleaner and scrub. After you rinse, examine the spot. If you see an oil film on the rinse water or if water beads up on the spot, scrub again. You can wash the entire driveway surface at this time, since you'll have to wait one or two days for the asphalt to dry anyway. When it's dry, apply primer (Photo 7) to the spots.
Before you apply sealer, check the weather forecast and the sealer's label to make sure you'll get good drying conditions. Seal coats are water-based, and a rainfall before they dry will ruin them. Drying times will slow in cooler and more humid conditions.
Tip: If you're a rookie, work on a cooler, more humid day to slow drying so you have more time to spread the sealer smoothly.
Coat the edges first using a stiff brush such as a masonry brush (Photo 8). Then coat the entire driveway using a seal coating broom or squeegee (Photo 9). Stir the sealer before application even if the label claims it's a no-mix formula. Seal coating isn't difficult, but it is messy. Wear old shoes and clothing you can toss. The worst mistake is stepping in drips, then tracking the seal coat across concrete or inside your home.
Be sure to read the manufacturer's directions and follow the recommended spread rate. Take care not to lay it on too thick. Puddles or thick areas will probably peel. Work the sealer into the surface. Although some sealers require only one coat, it's better to have two thin coats than one thick coat. And you're less likely to leave ridges or brush marks. Finally, surround the driveway with stakes and string or tape. Keep everyone, including pets, off the finished surface until it dries. Otherwise you might find black, gooey paw prints on your kitchen floor!
Talk to a Pro
Before diving into an asphalt driveway repair project, call in a local pro for an estimate. (Search online or look in your yellow pages under “Asphalt.”) That way, you can compare the estimate with the cost of doing it yourself. The tools and materials purchased from a local home center for our 700-sq.-ft. driveway cost about $130. The pro bid was $300. Keep in mind that a quality professional job will include hot-melt crack filler and hot asphalt patching material. These materials provide longer-lasting repairs than you can make yourself. And if your driveway has lots of heavily cracked areas or large potholes, the gravel base probably needs repair; that's a job best left to pros.
If you decide to hire a contractor, avoid those who give bids over the phone. Good contractors will examine your driveway and give you a detailed bid. They should also tell you the products they'll use and all the steps in their process. Seal coating warranties are often for no more than a year. But patches should be guaranteed for the life of the driveway.