Why do streets not get a coat of sealant like parking lots do?


Why do I see entire parking lots get a coat of sealant, but never really see streets or highways get a large coat of sealant?


For example: [https://youtu.be/Lmd1r0P0GWE?t=192](https://youtu.be/Lmd1r0P0GWE?t=192)

In: 709

It’s because it would cost too much and the value that the coating gives is miniscule at best even for a driveway or parking lot.

The only real benefit that asphalt coatings provide is a crisp, uniform, black look. This look will only last a year or two under light use as the UV in sunlight breaks it down and the top aggregate is exposed again. Under heavy use the look would last weeks at best before the preferred grooves are worn down again.

If an asphalt surface is never sealed it will UV degrade only a finite amount before it goes steady state. The seal coat doesn’t prevent cracks and cracks are what destroy the surface which is why you’ll see the road services putting a tar/rubber caulking into the cracks on the roadway if it’s in a climate zone that experiences frequent freeze/thaw cycles.

There are a couple of reasons. Regular roads have better drainage, both by design and because cars go over it regularly at speed which tends to move the water off of them. A parking lot will potentially have a lot of standing water. Plus, regular roads are maintained by cities and they have a schedule for a grind up and re-asphalt, a parking lot will potentially not have the same level of attention and a higher bar to have the lot chewed up and re-asphalted.

I’ve heard that the only real advantage of coating a driveway is that the darker surface will absorb more energy from the sun and melt off snow easier.

Is that not what a Chip and Seal is? We do those all the time in Northern Ohio

They literally did this very thing to all the streets in my neighborhood just a few weeks ago. So at least some streets get it done.