The Asphalt Myth: Sealcoat Isn't What Saves Your Parking Lot. Crack Filling Is.
Most asphalt fails from the bottom up, when water gets through cracks into the base and weakens it. Sealcoat protects the surface, but it doesn't keep water out of open cracks. That is why we recommend crack filling every year and sealcoat every three to five years, instead of doing both only every few years.
Ask most people how to take care of asphalt and they will say sealcoat it. A fresh black coat looks great and does protect the surface. But in our experience, the lots that last are the ones where the cracks get filled every year. The real enemy of asphalt is water underneath it.
How asphalt actually fails
Asphalt is a flexible surface sitting on a compacted base. The base carries the load. When cracks open up and stay open, rain and irrigation water run down through them into the base. Wet base loses strength, the surface above it flexes more under traffic, and small cracks turn into spider-web cracking, potholes and sinking areas. Pavement research says the same thing: water getting in through cracks speeds up deterioration and leads to moisture damage, base failure and potholes.
Once the base has failed, no coating can fix it. That area has to be cut out and rebuilt.
What sealcoat does, and doesn't do
Sealcoat is a surface treatment. It protects the top of the asphalt from sun and oxidation and restores the dark color. What it doesn't do is fill and seal working cracks or level a surface that has started to sink. Coating over open cracks hides them for a season, and the water keeps getting in.
Our schedule: crack fill every year, sealcoat every 3 to 5 years
- Every year: walk the lot and fill the cracks before the rainy season, so water can't reach the base.
- Every 3 to 5 years: crack fill, then sealcoat and restripe.
- As needed: fix low spots and drainage so water runs off instead of sitting on the pavement.
The common approach, doing crack fill and sealcoat together only every few years, leaves cracks open in between. That gap is when the base takes on water.
Why this saves money
Crack filling is a small, routine cost. Patching failed base, overlays and full replacement are not. Keeping water out is the cheapest way to push those bigger projects further into the future.
Signs you are past maintenance
- Spider-web or "alligator" cracking.
- Potholes or areas that move under a car.
- Ponding water that sits after storms.
If you see these, the base may already be wet or failed, and we will tell you before you pay for a coating.
How we help
We crack fill, sealcoat, patch, overlay and restripe parking lots and driveways across Greater Los Angeles, and we price maintenance, repair and full replacement side by side so you can compare. Call (800) 606-3880 to set up a yearly crack-fill walk.
Sources
- Roads & Bridges, Challenges and solutions for crack sealing in asphalt pavements (2019)
- Maintenance schedule: JFPEC field practice.