Many residential and commercial properties have asphalt paving needs. If you have an existing asphalt surface on your property, you might wonder whether you should tear it up and replace it or put another layer on top. Within the industry, this is known as an asphalt overlay.
Is an asphalt overlay suitable for your project, though? Let's look at how you can judge.
Sources of Damage
Generally, an overlay will work best when there is little to no damage. The surface might be cracked a bit from weathering, but it doesn't have deep potholes or large heaves. A driveway that's being driven upward by tree roots, for example, is a poor candidate for an overlay. Conversely, a parking lot that's just too cracked for more sealcoating probably is a good candidate.
The depth of the damage also matters. A contractor can usually patch a few light potholes before doing an overlay, for example. If you have a street that has deteriorated to the point that the gravel or concrete base is showing and crumbling, you may need to do new asphalt paving.
Even if the asphalt surface is still in good shape, adjoining features can create problems. For example, adding asphalt layers can turn a storm drain or manhole cover into a bit of a crater. The asphalt layer is usually a couple of inches thick, and that means the adjoining features end up lower relative to the top of the new surface. If you keep adding layers like this without ever milling down to the base, the hole for a drain or access point could be deep enough to trip pedestrians or damage the suspension systems of vehicles.
You may be able to do some angular milling to reduce the slope of these features. However, the accumulation of layers will eventually become a hazard after a couple of consecutive overlays.
Size of the Affected Area
Typically, an asphalt overlay works best in a large location. Doing more prep work and spreading more materials will be more cost-effective in a spot like a large parking lot, long driveway, or street. In a smaller area, you may be further ahead to remove the existing surface and do new asphalt paving.
You also need to be careful about the slope of the surface since this significantly affects drainage. An overlay can be problematic if it worsens an existing slope because it can cause more run-off. On a flat surface that has no drainage issues, though, an asphalt overlay may be the most cost-effective option.