Sealcoating a driveway that still has open cracks is one of the more common ways to waste a weekend. The coating bridges the gap like a skin, the crack keeps moving underneath, and the film splits along the same line within a season. Crack filler goes in first, and the right filler depends on how wide the crack is and how many of them you are dealing with.
Which Asphalt Cracks Are Worth Filling
Not every crack is a filler job. North Dakota’s Local Technical Assistance Program describes cracks that are clean, dry and at least 1/8 inch wide as candidates for sealing or filling, and it treats cracks wider than 1.5 inches as something to evaluate, because they are often a sign of pavement failure. The Colorado Asphalt Pavement Association draws the line a little tighter: seal cracks from 1/4 inch to 1 inch, and repair anything over 1 inch. Both sources also steer away from sealing the pattern that looks like an alligator’s skin: NDLTAP calls block and fatigue cracks symptoms of pavement failure, and the Colorado sheet says those areas should be repaired rather than sealed. NDLTAP’s crack seal review and the Colorado Asphalt Pavement Association’s best practices sheet are written for road crews, but a driveway is the same material at a smaller scale.
In practice that gives you three groups. Hairline to about 1/2 inch cracks are a filler job. Cracks around an inch are borderline and depend on the product. Wide, deep or interconnected cracking is a patch or resurfacing decision, covered at the end.
Prep Decides the Repair More Than the Product
Both guidelines are blunt about this. A crack has to be free of moisture, dirt, debris, vegetation and chemical deicers before anything goes in, and the Colorado sheet specifies compressed air or a heat lance for cleaning. At home that means a wire brush or screwdriver to dig out loose material and weeds, then a leaf blower or compressed air to clear the dust. Fill when the pavement is dry and the temperature is at least 45 degrees Fahrenheit and rising, which is the Colorado threshold for placing sealant. NDLTAP puts the same practical limit on cold-pour products at ambient temperatures above 50 degrees. A filler that goes into a damp or dusty crack bonds to the dirt, not the asphalt, and lets go at the first freeze.
Scattered Cracks Up to Roughly Half an Inch: The Caulk-Gun Route
When the cracks are few and you want control over where the material goes, a cartridge is the easier tool. SIKA Sikaflex-410 Asphalt Crack Sealant comes in a 9 fl oz cartridge for a standard caulk gun and is self-leveling, so it settles into the crack and finds its own level instead of standing proud of the surface. The listing states it fills cracks up to 1.5 inches, skins over in under an hour and stays elastic, and at the time of writing it shows about 4.5 stars across roughly 1,100 ratings. Treat the 1.5 inch figure as an upper limit from the manufacturer, not a recommendation: the road-agency guidance above reserves cold-pour products for thinner cracks. This is an affiliate link (see our disclosure for details).
Lots of Thin Cracks: The Pour-Bottle Route
A driveway with a dozen cracks across its length is a different job. A cartridge means a lot of squeezing, a lot of stopping, and a lot of cartridges. Bluestar Flexible Asphalt Crack Filler comes in a 16 fl oz pour bottle that needs no special tools, is made in the USA, and is rated for cracks up to 1 inch wide. It is formulated to stay flexible in both hot and cold weather, and it has around 1,100 ratings at roughly 4.3 stars. The trade-off is control: pouring is fast but less precise than a gun, so it suits cracks you can fill in one steady pass. This is an affiliate link (see our disclosure for details).
Cold-Pour Versus Hot-Pour, and Where Each Stops
Both products above are applied cold, which is what makes them practical for a homeowner. It also sets their ceiling. NDLTAP recommends hot-pour sealant for general use and for all crack sizes, and describes cold-pour sealant as generally for thinner cracks, 3/16 inch or less. Colorado’s sheet agrees that cold pour may be effective but that hot pour will potentially last longer. That does not make a cold-pour filler a bad choice for a driveway. It means that a crack of 3/16 inch or less is the best fit, and the closer a crack gets to an inch, the more you should expect to redo it sooner and keep an eye on it each spring.
Fill First, Then Sealcoat
The order matters. Fill the cracks, let the filler cure fully according to its label, and only then apply a sealcoat over the whole surface. Sealcoat over unfilled cracks is the skin problem from the start of this guide, and coating over filler that has not cured is a gamble you do not need to take. The label on your specific filler sets the cure time, and the label on your sealcoat sets the minimum temperature, so read both before you pick a weekend. Our guide to choosing a driveway sealer covers the sealcoat step, including what to check on the label.
If your driveway is concrete rather than asphalt, none of this applies directly. See our guide to concrete crack fillers and the one for concrete floor cracks instead.
When Filler Is the Wrong Answer
If the cracks are connected into a web, the surface is sinking, or a crack has opened wider than about an inch and a half, the filler is covering a symptom. Interconnected alligator cracking points to a base problem, and the Colorado guidance says those areas should be repaired, not sealed. At that point the useful question is no longer which filler to buy but whether the section needs a patch, a resurfacing, or a paving contractor to look at the base. Get a quote before you spend money on product that will not hold.
The same asphalt-based patching idea shows up on roofs, with different limits for wet weather and movement. Our guide to roof cement and when it is only a stopgap covers that side of it.
Etienne Basson maintains and repairs his own home, and writes practical guides on choosing the right materials and products for repair and finishing jobs: fillers, sealants, adhesives, and similar. He focuses on what actually works for a specific job, not just a spec sheet.