Pervious Asphalt or Pervious Concrete?
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On the left you see traditional sealed Asphalt paving. On the right you see permeable asphalt- a bit rougher and sometimes can absorb water!
Lately we have been coming across a bit of pervious asphalt. Two instances come to mind that we want to share with you-
A case of pervious asphalt for a church in Costa Mesa. A builder called us, concerned that his church, for whom he was doing some sizable improvements to the church campus, was committing to a new large parking lot that the local regulations required being permeable. Their designer, with an eye for value, no doubt, specified pervious asphalt. Our builder was concerned about the longevity and durability of the material. Since he was a part of the church community, he was concerned he would hear about any issues over time. So he called us! We priced out a pervious concrete alternative. It was more expensive then the asphalt - but it was also going to be a multi-decade investment in a low maintenance permeable pavement. We went to the church and discussed it with another church member - and they agreed. Pervious concrete for them, was a better, more sustainable investment for their church. We installed the pervious concrete parking lot and it looks great!
There is a time and place for all materials - but if you are making an investment in a property for the long term, pervious concrete is your best value as a durable, low-maintenance passive infiltration device that your friends and community members can walk and roll across with no issue for years to come!
Pervious asphalt and pervious ramps. Another project just came across our desk for some custom ramps to roll large equipment into and out of a new showroom. The equipment weighed as much as a car but with teeny tiny wheels - and the local permitting body was requiring that this improvement be pervious. So they needed a rigid, flat and smooth surface that drained. Pervious concrete and PerkTop to the rescue! Pervious concrete is traditionally made with a 3/8” aggregate. It can be crushed or round but the sizing being consistent is the most important aspect. Despite the fact that 3/8” aggregate pervious concrete is very flat, and is considered an acceptable pavement for ADA applications, these clients wanted something smoother. We offered them PerkTop, a fine grain permeable topper that is added as a final surface to pervious concrete in thicknesses of 3/8”-1/2”. They liked it!
While we were there installing, we discovered pervious asphalt in the wild. During the pandemic they had completed the office and redid the parking lot with many patches of permeable asphalt dotted throughout the asphalt parking lot. It was in the best shape of any permeable asphalt I had ever seen. It turned out, that despite being 2.5 years old, it had received very little traffic until this year. Perhaps because of the limited traffic it was holding up well. We tested it, and sure enough it drained.
The point is, permeable asphalt is a possibility for permeable or pervious paving. It tends not to hold up in the long term, and, by virtue of its shorter useful life, must be redone regularly. If the regular re-paving is factored into the upfront price, pervious concrete and pervious asphalt would be comparable. If you are selling your building in the short term, pervious asphalt might be a good choice to check a permitting box. If you are making a capital investment in your portfolio, your community or your home, consider making it a solid one with pervious concrete.