What's often called alligator cracking — we call it spider cracking — is one of the most misunderstood forms of pavement damage. It's frequently treated as a surface problem when it's actually a structural one. That distinction matters a great deal, because the wrong treatment wastes money and leaves the real damage continuing to grow underneath.
What spider cracking actually is
Spider cracking is a pattern of interconnected, interlocking cracks that form a web across an area of asphalt. Unlike a simple linear crack that runs in a more or less straight line, spider cracking fans out in multiple directions from an area of failure, creating a pattern where individual crack paths meet and divide.
The defining characteristic of spider cracking isn't the surface appearance — it's what caused it. Spider cracking is a sign of sub-base failure. The asphalt itself may still be intact as a material, but the layer beneath it — the compacted gravel or stone base that gives the asphalt something solid to rest on — has deteriorated, shifted, or become saturated with water. The asphalt above it is now bending under vehicle load rather than being supported, and that repeated flexing under weight is what generates the interconnected crack pattern.
What causes it
Advanced water infiltration. The most common cause in Rhode Island is prolonged water damage to the sub-base. Water that reaches the sub-base through open cracks or deteriorated asphalt saturates the base material, reducing its load-bearing capacity. The asphalt above a wet, weakened sub-base flexes under vehicle weight in a way that properly supported asphalt doesn't — and that flexing breaks it.
Long-term UV oxidation. Asphalt that hasn't been maintained becomes brittle over years of UV exposure. Brittle asphalt fractures under stress rather than flexing slightly as healthy asphalt does. If the surface has been neglected long enough to become significantly oxidized, even normal traffic loads can initiate cracking.
Age and deferred maintenance. Spider cracking doesn't appear overnight in most cases. It's typically the end point of a multi-year process: surface cracks that went unfilled → water infiltration → sub-base saturation → load failure → spider cracking. Each step is an opportunity to stop the progression. By the time you're looking at a spider-cracked surface, several of those steps have already passed.
Why sealcoating cannot fix spider cracking
This is the most important thing to understand about spider cracking, and it's where we see the most overpromising in this industry.
Sealcoating is a surface treatment. It protects the asphalt it's applied to, but it cannot restore a compromised sub-base. Applying sealer over a spider-cracked area makes the surface look better temporarily — the cracks are covered cosmetically — but the sub-base damage is still there. The asphalt is still bending under load. The cracks will re-emerge through the sealer, often within a single season, because nothing that was causing them has changed.
Similarly, filling individual spider cracks directly with crack filler doesn't work. The area continues to flex under vehicle weight, and any filler applied inside a spider-cracked zone will be broken apart by the same movement that created the cracks in the first place. The underlying problem is structural, and structural problems require structural solutions.
If a contractor offers to "fix" spider cracking with sealcoating alone, they are either misinformed or they're selling you something that won't solve your problem. An honest assessment of spider cracking will always include a discussion of what the surface actually needs — which is not a sealer.
What can actually be done
The realistic options for spider-cracked pavement depend on how extensive the damage is and what the sub-base condition looks like.
Perimeter crack filling to contain spread. If the spider-cracked area is relatively bounded — contained to one section of a driveway or lot — and the surrounding pavement is otherwise in decent condition, filling the cracks around the perimeter of the spider-cracked zone can slow or stop the damage from spreading outward. This isn't a fix for the spider-cracked area itself. It's a defensive move to protect the surrounding pavement while you plan a more comprehensive repair. See our Crack Filling Guide for more on how we approach perimeter containment.
Patching the affected section. For a localized area of spider cracking, removing the damaged asphalt, repairing the sub-base beneath it, and patching with new asphalt is the correct repair. The patch restores both surface integrity and sub-base support. This is significantly more expensive than maintenance sealing, but it actually fixes the problem.
Full resurfacing. If spider cracking is extensive — covering large portions of the driveway or lot — patching in multiple locations may be less cost-effective than resurfacing the affected area entirely. Resurfacing involves milling or removing the existing asphalt and installing fresh material, which also gives the opportunity to inspect and repair the sub-base where needed.
How to tell how bad it is
Not all spider cracking is equally severe. Early-stage spider cracking — cracks that are still narrow, the asphalt between them still relatively solid — is less urgent than advanced spider cracking where the sections between cracks are loose, shifting, or depressed. A surface that's starting to show the beginning of the pattern is a different situation than one where pavement fragments move underfoot.
The best way to assess it is to have someone walk the affected area and check: Are the pieces between cracks solid or loose? Is the area depressed relative to surrounding pavement? Does the surface flex visibly under foot pressure? These are signs that the sub-base failure is active and the damage is progressing.
If you're looking at a surface with spider cracking and trying to figure out what it actually needs, a free assessment is a reasonable place to start. The answer may not be what you were hoping for, but knowing what you're dealing with is better than spending money on a treatment that won't hold.