Blacktop and Beyond
Renewal and replacement options for the driveway that leads to your door
Driveways aren't just for cars. Many of the 75 million driveways in the U.S. do double duty as play areas and convenient work spaces for all kinds of projects. But an increasing number of driveways are showing their age: cracks, heaving, spalling and other signs of distress. Many of these surfaces can be renewed with the procedures described in "Renewing Your Driveway." Others will have to be replaced.
Although 90 percent of driveways in the United States are either asphalt or concrete, there are a number of other options including crushed stone, gravel, cobblestone and interlocking concrete pavers in a variety of patterns. Prices range from $1 per square foot for stone and gravel to $13 or more for cobblestone paving.
To make your decision easier, we'll lay out the pros and cons as well as costs for each of the four major driveway materials, and include a few of our own recommendations. But first we'll detail repair methods for concrete and asphalt to help you make the driveway (and basketball court/outdoor workshop) last as long as possible.
REMOVE dirt and weeds from cracks with a trowel or screwdriver and sweep out loose dirt and debris.
Renewing Your Driveway: Repairing Concrete
Even if your driveway is an expanse of puddles and potholes, it pays to explore renewing it first. It's a simple matter of dollars. For example, an asphalt topcoat costs about $2 per square foot - roughly a third of the tab for a complete driveway redo that includes soil prep, gravel and two coats of asphalt.
If your driveway is crumbling or has heaved or subsided in a major way, then your best option is to replace it. The same applies if it's allowing water to seep into the subsoil around your home. But often the problem is just cracks, which let in water that erodes the driveway base and allows freezing temperatures to do further damage. Nearly any size crack can be patched with concrete or cold-patch asphalt, depending on your driveway type, or with some very effective specialty materials.
Clean cracks and holes of plants and debris, then hose them clean and spray them with weed killer. Effective patching products for cracks up to 3/8 in. wide include UGL's Masonry Crack Filler ($3 a tube), Ardex's A-300 ($47 for a large bag) and Quikrete's Concrete Crack Sealer ($6.50 a quart). For holes or cracks larger than 3/8 in., use either Concrete Repair ($2.50 per quart) or Vinyl Concrete Patcher ($4.50 per half gallon), both from Quikrete. Or, you can simply mix concrete and apply it with a trowel.
To fix large holes and deep cracks, fill them with gravel to within 4 in. of the surface, pour in concrete, tamp with a magnesium float and finish with a flat trowel or broom to match the existing finish. However, the larger the patch, the shorter its longevity - winter freeze/thaw cycles that exert pressure of 30,000 psi can make short work of big repairs.
After patching, remove any spots with a specialty cleaner, such as Quikrete's Concrete and Asphalt Cleaner ($4.50 a quart). Then seal the repair to keep water out. UGL's Concrete Sealer ($13 a gallon, which treats 400 sq. ft.) is an affordable choice. The home-brew version: a 50-50 mix of linseed oil and mineral spirits. But keep in mind this sealer darkens the concrete.
CLEAN cracks with high-pressure spray from a hose, then treat them with weed killer before patching.
As with concrete, clean cracks of plants and debris, hose them clean and spray them with weed killer. Then do your patching when temperatures are at least 60°F so the repair material will cure. Fill 1/2-in. cracks with sand to within 1/4 in. of the surface, then add an asphalt filler, such as Quikrete's Blacktop Repair ($2 a quart) or UGL's Driveway Crack Filler ($3 a tube). An alternative is Dalton's Pli-Stix, a ropelike crack and joint sealer you melt in place with a torch.
For holes 1 to 2 in. wide, use Dalton's Tamp & Set Patch ($9 for 3 1/2 gal.) or Trowel & Spread Patch ($6 per gallon). You can also mix sand and blacktop sealer until stiff and apply it with a trowel. Wear gloves and use mineral spirits for cleanup. For deeper holes, pour in gravel to within 4 in. of the surface, then trowel in Dalton's Super Patch ($7 per gallon). Or, shovel in cold-patch asphalt in 1-in. layers, packing each firmly as you go with the end of a 4X4 or the head of sledgehammer.
Finish by sealing your asphalt driveway after patching and every other year thereafter. A 5-gal. pail of sealer ($9 to $16) will cover around 300 sq. ft.
PATCH cracks using one of the specialized concrete or asphalt repair products mentioned in this story. Fill deep cracks with gravel or sand first.
Replacing Your Driveway
Large areas of concrete can't be resurfaced reliably. Your contractor will have to break up the old slab and pour a new one.
For asphalt, the contractor can simply apply a base and finish coat over the existing asphalt. All cracks should be treated with weed killer and filled, and the driveway should be graded if it's not draining properly. The surface layer of asphalt should be a consistent 1 1/2 in. throughout - which could require some excavation around door openings and garage thresholds.
As with all professional work, a new driveway is as good as the contractor who puts it in. Check with your neighbors who have had driveway work done. You can also find a qualified pro through a local masonry or asphalt supply house. Or check the yellow pages under "Paving Contractors" and "Asphalt and Asphalt Products." Then ask to inspect driveways they completed four or five years ago to see how they held up. Look for cracking and heaving, which indicate poor soil preparation or drainage.
Once you've chosen a pro, be sure the contract guarantees the work for at least two years. It should also stipulate a payment schedule with no more than a third of the total up front and a clause ensuring that your lawn will be restored to preconstruction condition. The contract should also include:
For a new asphalt or concrete driveway installed where none existed, a compacted gravel layer 8 to 10 in. deep of 3/4-minus gravel (no stone is bigger than 3/4 in.). If the soil is unstable, a netlike geotextile fabric may be required beneath the gravel, as may drain tile - 4-in. perforated pipe that drains the perimeter of the driveway.
•For any concrete driveway, a slab (at least 5 in. thick) made of 4,000-psi, air-entrained concrete that's reinforced with wire mesh or rebar; the slab should be thicker if you have heavy vehicles. In cold climates where road salt is used extensively, some contractors, concerned it will corrode in the concrete over time and create voids that lead to fracturing, omit the steel reinforcing.
•For new and existing asphalt, two layers: The first should be a 2 1/2-in. base layer of asphalt containing 1/2 to 3/4 in. of stone, the second a 1 1/2-in. topcoat containing 3/8 in. of stone. Total asphalt depth should be at least 3 1/2 in. - thicker if you have heavy vehicles.
Driveway Surfacing Choices: Concrete
What's out there: Choices include plain concrete; concrete colored with pigments or acid-staining; colored and stamped concrete that mimics stone; and exposed aggregate that allows the top layer of textured gravel to show through.
Pros: Long-lasting. Depending on the weather, exposure to road salt and subsoil preparation, concrete should last at least15 years and often more than 50 years with biannual sealing and proper drainage. Precise edge treatments are a snap; its smooth surface is ideal for basketball and makes snow removal easy.
Cons: You'll have to wait seven days for the concrete to cure before driving on it. Cracking is inevitable - particularly in freeze/thaw conditions - and repairs stand out. Concrete can't be relayered like asphalt, and should be sealed every two years. The finish can vary widely depending on the installer. Oil stains are tough to remove, colored concrete fades over time. Because concrete cracks when not supported, poor drainage and unstable soil can reduce life span to just five to eight years.
Cost: $3 to $4 per square foot for a plain concrete slab and $5 for pigmented concrete, $7 for exposed aggregate and $8 for an acid-etched finish. If you're putting in a driveway where none existed, add $1 to $2.50 per square foot for an 8- to 10-in. gravel bed beneath the concrete.
Recommendations: Be sure any bedding or gravel base, including a pulverized slab, is compacted and the ground well-drained. A new gravel base should be 3/4-minus gravel and 8 to 10 in. deep. After concrete is poured, to prevent cracking, use a sprinkler to keep concrete moist as it cures.
Driveway Surfacing Choices: Asphalt
What's out there: Choices include plain hot-mix asphalt; chip seal with gravel pressed in for texture; pattern-stamped asphalt; and acrylic polymer colors.
Pros: Resists cracks, because it flexes with minor ground movement. Asphalt is easy to contour, and usually lasts 15 to 20 years when properly maintained. Topcoats can often be applied over existing layers.
Cons: Getting straight, clean edges is difficult. Asphalt can deteriorate in as little as five years without proper drainage, and should be resealed every two years. Burdock and other plants can grow through it, breaking it up.
Cost: Prices vary considerably by region. Figure on $1 to $2.50 per square foot for the base coat. Geotextile and drains cost extra. Then add $1 to $2.50 per square foot for a plain topcoat, about $3.50 for chip seal or $3 to $5 for a stamped or colored topcoat. If you're putting in a driveway where none existed, add $1 to $2.50 per square foot for an 8- to 10-in. gravel layer beneath the asphalt.
Recommendations: Remember that an asphalt topcoat is only as good as the base and lasts longest with proper drainage. Have a soil sterilizer applied beneath a new gravel layer to kill weeds. And apply a latex sealer every two years to keep out water and improve appearance.
Crushed Stone and Gravel
What's out there: Choices include crushed shale, granite, limestone and concrete, along with gravel in various sizes and colors.
Pros: Both stone and gravel are economical and both offer good freeze/thaw resistance. No base is required - just dump and spread. And when stone or gravel compacts or scatters, adding a fill coat of pea gravel, called redressing, is easy.
Cons: Stone and gravel scatter easily and develop ruts. Also, smaller stones, or fines, tend to sink after four or five years, leaving larger stones on top. Periodic redressing is a necessity. Both materials are difficult to plow or shovel in snow climates, and bordering areas typically require a spring raking.
Cost: Crushed stone and gravel costs around $1 per square foot for a 2-in. layer.
Recommendations: When a fill coat of pea gravel is necessary to fill in ruts, be sure to redress the entire driveway for consistency since stone size and color can vary depending on the source. For new gravel driveways, use 3/4-minus stone for stability. Depth required ranges from 1 1/2 in. for stable soil to 6 to 8 in. for unstable soil.
Pavers and Cobblestone
What's out there: Pavers come in a wide range of shapes and patterns, from unusual ones like trefoil and anvil to common designs like bow tie, keyhole and hexagon. Cobblestone, or Belgian block, is more traditional and comes only in a rectangular shape.
Pros: Lots of choices for pavers. Cobblestones easily last 100 years, pavers somewhat less depending on soil preparation and drainage. Stained and broken pavers are easy to replace, as are individual cobblestones.
Although cobblestones tend to trap ice and snow, removing both is easy with pavers if they're properly installed.
Cons: Pavers are relatively expensive, and cobblestone tops the cost spectrum. Installation requires careful excavating and preparation. Pavers and cobblestones can settle unevenly if sand layer over gravel base compacts, while the wide joints between cobblestones invite weeds and grass.
Cost: From 50 cents to $1.50 each for pavers, or $6 to $10 per square foot installed with bed preparation depending on the intricacy of the design. For cobblestone, figure on about $13 per square foot.
Recommendations: Visit a four-year-old job and check for settling before hiring a contractor. Be wary of landscapers installing pavers or cobblestones as a sideline - specialized skills are required. Remember that these surfaces are only as good as the compacted sand and crushed stone they're laid on. Insist on compacted subsoil, a 10-in. layer of 3/4-minus gravel and a 1 1/2-in. layer of coarse bedding sand with compaction between layers. Cobblestones are laid up like brick, but pavers require a plastic retaining edge. The main supplier is Pave Edge ($2 per foot).
Where to Find it
1155 Stoops Ferry Rd., Dept. TH998
Coraopolis, PA 15108
131 Willow St., Dept. TH998
Cheshire, CT 06410
8509 Sunstate St., Dept. TH998
Tampa, FL 33634
Interlocking Concrete Pavement Institute
1444 I St. NW, Suite 700, Dept. TH998
Washington, DC 20005-2210
Offers how-to installation guide for pavers
Pave Tech Inc.
P.O. Box 31126, Dept. TH998
Bloomington, MN 55431
Offers how-to installation guide for pavers, and sells a full range of equipment
Box 647, Dept. TH998
Olive Branch, MS 38654
2987 Clairmont Rd., Suite 500, Dept. TH998
Atlanta, GA 30329
United Gilsonite Laboratories
Box 70, Dept. TH998
Scranton, PA 18501-0070