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1. Why is a fog seal done?

Asphalt streets consist of a 1½ to 2 inch layer of asphaltic concrete most people just call asphalt or pavement. Over time, the asphalt ages, weathers, and oxidizes. It becomes brittle and cracks. While the old surface appears smooth, it contains hairline cracks that if not treated would continue to widen, deepen and eventually form potholes.

2. How long does a fog seal take?

We are asking residents to please make accommodations for not accessing the cul-de-sac, or their driveways, for approximately 2 to 2 ½ hours. In most cul-de-sacs, the application of the fog seal will only take about 20 to 30 minutes. During this time, the roadway in front of a residence will be an active work zone. During the remaining 2 hours, the cul-de-sac will be closed to allow the asphalt to cure. Please be aware that temperature, humidity, and cloud cover may increase curing time. 

3. When can I walk on the asphalt again?

It is best to wait until the surface no longer appears wet. There will be a Williamson County representative monitoring the curing process on all fresh fog seals. Please ask him / her if it is safe to walk or drive on the cul-de-sac.

4. How often is fog seal maintenance required?

Because the asphalt that is used for a fog seal is treated to become more rigid than the asphalt used in a seal coat, it will crack more frequently. Therefore, it is anticipated that a resurfacing of the cul-de-sacs will occur every 2 to 3 years. Seal Coat maintenance is often performed on an 8 to 10 year basis. If preventive maintenance (crack sealing and fog seal resurfacing) is conducted on Williamson County roads and streets on a routine basis, the existing pavement structure will last for many decades.

5. Why was a fog seal applied on the cul-de-sacs instead of a seal coat like the straight sections of road?

Tandem axle, double tire, garbage trucks make sharp turns in cul-de-sac bubbles and cut into a fresh seal coat thereby peeling up large sections of the surface.  The asphalt that is being used with the Fog Seal is specially treated with polymers and pulverized tire rubber to make it more unyielding to the heavy, slow-speed turning movements at the end of the street.

6. Why not pave the street with material like the one we already have? What is the difference in cost?

What the residents are used to driving on is a pavement structure that has a hot mix asphalt pavement (HMAC) surface with a flexible crushed rock base below it. The cost to resurface an existing road using a standard HMACP overlay is 5 to 6 times more expensive than resurfacing a road with a seal coat. Should the roads not be resurfaced at all, they will continue to degrade and there comes a point when resurfacing maintenance is no longer effective and the road would need to be rebuilt. The cost to rebuild a road is 10 to 15 times greater than the cost of seal coating.

7. Where else has the fog seal process been used?

The City of Austin and the City of San Antonio also resurface cul-de-sacs using a fog seal. You may wish to view some cul-de-sacs in the following Williamson County neighborhoods that have recently been fog-sealed: Block House Creek or Brushy Creek North.

8. Where do I go for more information?

You may call our Resurfacing Hotline, 512-943-3393, to hear daily updates of roads on which our crews are currently working or you may visit our county Roads page.

9. What if I need to leave my house while the fog seal is curing?

You may want to consider parking your car on the straight section of your street on the day your cul-de-sac is scheduled to be fog sealed. Please check Resurfacing Schedule to see what streets will be resurfaced in the next 2 days or call our resurfacing hotline 512-943-3393 for additional information.