When was the last time you thought about your parking lot? The honest answer most likely is, not in recent memory. We know it’s not a question of out of sight–out of mind, parking lots are highly visible. However, they aren’t very interesting.
As a result, paved areas don’t always get the maintenance attention they need, and that is a potentially serious problem for not only the owners of commercial properties but also the HOAs that manage residential condominium communities. A poorly maintained parking lot is not only an eyesore, detracting from a property’s curb appeal, it could also be a liability risk. Customers or residents who trip over cracks or whose cars are damaged by potholes might sue the property owner.
Paved areas, if well constructed and well maintained, can last between 25 and 30+ years depending on where they are located and how they are used. Unfortunately, parking lots, sidewalks, and driveways are often afterthoughts—the final items on a construction checklist. They are typically undertaken near the end of the project when funds are low and the developer’s attention is waning.
Doing it Right
A parking lot begins with good soil compacted properly to create a stable base that should be covered by two layers of asphalt―a base course on bottom and a wearing course on top. There is some disagreement about the desired thickness, but no question that the thicker the asphalt layers, the longer their life. The industry standard calls for a combined thickness of between two and one half and five inches, with the top layer thicker than the bottom.
Only about half of the parking lots we inspect meet that standard. Many fall short, with both layers sometimes totaling less than two inches. If the asphalt layers are too thin, if the underlying soil is poor, or if the area isn’t paved uniformly, the surface will form holes, crack and split, requiring constant repairs and premature repaving.
Geography and weather play a huge role in the expected useful life of your parking lot:
- Harsh winters and the damage inflicted by the steel blades of snow plows take a toll in New England and other cold climates.
- Extreme heat and exposure to the blazing sun do the damage in the south and southwest.
- Pavement in hotter areas may require the application of a sealant to smooth over holes and cracks in less than a year after being laid.
- Pavement in colder climates may require sealant to mitigate the damage inflicted by snow and ice.
Maintenance Guidelines
You can’t skimp on snow plowing or the application of de-icing materials, but some of those materials are harder on asphalt than others. It’s worth asking your snow removal contractor for recommendations. Proper application of the material is also essential. Adding more salt won’t necessarily improve its effectiveness and it will increase the cumulative damage to paved areas and reduce their useful life.
Poor drainage can also accelerate deterioration. Even the best laid surface will be compromised over time if areas of ponding water regularly occur. You can spot evidence of ponding even if it isn’t raining: areas of discoloration and collections of dirt, twigs, and other debris all indicate a drainage problem. All well drained parking lots require a decent slope and catch basins.
A few small cracks here and there will are the first sign of wear. They usually appear between years three and five, and filling them is the first line of defense. The important thing about cracks is, small ones will quickly become larger, so you don’t want to ignore them. They represent both a safety hazard and a structural concern. Water can seep through the cracks causing damage below the surface of the asphalt. In warm climates, the water will unsettle the soil, pushing the clay up against the asphalt and accelerating the deterioration process. In New England, water will trigger a destructive freeze-thaw-freeze process in the winter, which will also shorten the asphalt’s useful life.
You can deal with small cracks by filling them in. Contractors typically use a melt-in substance that won’t shrink after application. This is the product highway crews use because of its durability and ease of application. It is sold under several retail brand names, all variants of “hot-applied crack sealant.” Experts suggest that you fill cracks every two or three years, as part of a regular maintenance plan. If cracking becomes more widespread, you can take the next step, which is to apply a sealant to the entire paved area.
Resurfacing and Replacing
As asphalt ages, one or more sections may begin to break up or flake, indicating that the surface is beginning to deteriorate. Patching will temporarily take care of the problem. However, you don’t want to pave over the failed area. You need to cut out the deteriorated section, fill in the subsurface, then pave over that. This will give you a sturdier, longer-lasting repair. However, it is still a temporary fix, not a long lasting solution.
At some point, deterioration will accelerate, repairs will become more frequent requiring more aggressive and more expensive responses. One option is to resurface the area—either lay a new surface over the existing one, or remove the old asphalt and pave the area anew. These options make sense if the underlying soil base is stable. If the old surface failed prematurely because the underlying soil wasn’t stable, a new surface laid over that unstable soil won’t wear or fare any better.
If that is the case, it’s time to start over. The contractor should remove the old asphalt, scoop out the bad soil, replace it with gravel and stone to create a solid base, and then lay the new pavement over it. That’s the traditional approach. A newer technique calls for pulverizing the old asphalt and using it as a base for the new pavement. In addition to creating what contractors say is a “super-solid” base, pulverizing the old asphalt eliminates the cost of trucking it away and disposing of it at a hazardous waste site. Either technique will give you nice, new pavement that will last another 25 or 30 years or more.