What is Asphalt Driveway Sealing or Seal Coating?
Asphalt driveway sealing (also known as “ seal coating”) is the process of applying a protective coating to an asphalt-based driveway that helps protect the asphalt from the damaging effects of harsh weather, chemicals, and U.V. light while restoring the beauty of the driveway’s original black-top finish.
Why Should I Seal My Driveway?
Simply put, seal coating is a preventative measure to protect against further deterioration of asphalt driveways. While the breakdown of asphalt is inevitable, the speed at which it occurs and how far the degradation proceeds can be managed by seal coating the asphalt on a regular basis. Seal coating benefits the asphalt surface in multiple ways. The first major benefit is ‘weatherproofing’. Once the seal coating is applied, it helps prevent water or other liquids from penetrating and deteriorating the asphalt and the base layer. In the same way that excessive ultraviolet solar radiation affects human skin, it also breaks down asphalt and shortens its lifespan. Seal coating helps dampen the effects of these harmful rays thereby extending the life of the asphalt. As most homeowners realize, occasional dripping of motor oil and other vehicle fluids or spilling of lawnmower gasoline on your driveway is par for the course. Seal coating creates a protective barrier which slows, and sometimes prevents, the absorption of these harmful chemicals into the asphalt. Lastly, as any real estate agent will tell you, curb appeal matters. A regularly sealed asphalt surface helps maintain the attractive and clean black-top appearance of a newly paved driveway.
What Causes an Asphalt Driveway to Deteriorate?
The harsh reality is that the moment your asphalt driveway was laid, it started to deteriorate. The major causes of asphalt deterioration are oxidation, exposure to the elements, traffic volume and heavy loads.
Oxidation is a key factor to understand. The rate of oxidation is controlled by three main drivers: oxygen exposure, time, and temperature. Now the correlation of these three factors’ effect on the asphalt is simple: as oxygen exposure, time, and temperature rise, so does the rate of oxidation. The effects of oxidation show in the colour of the asphalt which goes from a freshly-paved dark black to a pale grey colour. This process can happen over a period of months or years depending on the elements. In addition to the colour change, the oxidation process causes the asphalt to become more brittle and to lose its elasticity, which leads to the next phase of asphalt degradation: cracking.
When the asphalt in your driveway becomes brittle, it loses its pliability and with that loss of pliability, the heavy load of vehicles can cause the asphalt to crack. Most often, the cracks first appear as straight line cracks. At the earliest stages, the development of these straight cracks can be maintained with crack sealer. If unmaintained, the moisture will not only degrade the surface but will also penetrate the base layer of the asphalt. The wearing out of the base layer forces the now brittle top layer to bear more of the stress of the vehicle weight, which leads to what is called asphalt fatigue.
If allowed to continue, the moisture seeping into the straight cracks will lead to a more expansive network of cracks often referred to “spider web” or “alligator” cracks. Further surface and sub-surface degradation occurs with the expansion of the cracks. If the cracks continue to be left unattended, the next stage of degradation is imminent; asphalt failure
Asphalt failure manifests itself it various ways. At this stage, the asphalt is so brittle and unable to support normal traffic stress that the asphalt surface will begin to separate and break off into pieces. Should a driveway be left unmaintained for too long, where the inevitable oxidation leads to the preventable state of failure, you could end up needing to replace the entire driveway or, at a minimum, undertake an extensive and costly patchwork and crack sealing project. Both these options are very expensive and can be avoided by simply implementing a proactive annual asphalt maintenance plan that will almost certainly save you many thousands of dollars in the long run.
What is the Professional Seal Coating Process?
The professional seal coating process differs from the do-it-yourself approach where a homeowner purchases a consumer-grade sealant product from a hardware store and applies it with a roller and/or squeegee. The primary difference is that a professional seal coating company should be using a commercial-grade, asphalt-based product that cannot be purchased in stores and they apply the sealant evenly to driveway by spraying it from a wand attached to a motorized pump system that dispenses a cold (i.e., not heated) sealant from a tank located in the bed of a truck or trailer or in a hand-pushed mobile cart invented by Canadian Property Stars, the largest driveway sealing company in Canada.
However, before the sealant is applied, the driveway must be cleaned. Even if you think your driveway is clean, trust us, it isn't. Exhaust gas contains combustion byproducts that deposit a light, sometimes oily film on your driveway. That film, along with dirt and tree sap, must come off so that sealant can properly adhere to the asphalt. Professional driveway sealing companies like Canadian Property Stars will first use a still bristle broom to loosen and remove the oily film, dirt, gravel, sand and other debris from the surface of your driveway. Next they will use use equipment such as a gas-powered blower to remove any residual material from the driveway. If necessary, they will also pull out any weeds that have sprouted up in the cracks in the asphalt. If the company offers it, the cracks in the driveway can be filled by hand using a rubberized crack filler. Lastly, before spraying the commercial sealant, the technician will tape off the edges of the driveway to prevent any sealant from contacting paver stones or concrete surfaces. Spraying the sealant is much more efficient than rolling. An experienced professional can apply just the right amount of sealant to a standard residential driveway in under 10 minutes. If it’s a windy day, the technician may use a thin handheld wooden board to prevent over-spray from occuring.
What is a Commercial-Grade Sealant?
The primary characteristic of a commercial-grade sealant for asphalt driveways is that they are petroleum-based product that are manufactured from asphalt cement (bitumen). One high-quality product used by leading commercial sealing companies such as Canadian Property Stars is a rapid-curing cutback asphalt. This is an ideal sealant since it will cure right into the driveway restoring the original properties of the asphalt surface. One way to describe the difference between using a commercial-grade sealant and an inferior quality consumer-grade sealant is to realize that sealing with many of the consumer products is like painting a piece of wood where the paint remains on the surface whereas sealing your driveway with a commercial product is like staining a piece of wood because the liquid asphalt sealant soaks right into the top layer of solid asphalt.
Frequently asked questions
How long until my freshly coated driveway is dry and I can park my car on it again?
12 hours may be enough if the weather is warm and the day has been sunny. 24 hours is typically more than enough for the sealant to cure and dry.
How often should I seal my driveway?
Once a year is not too often as long as it is not too thickly applied. Every second year is probably the longest you should wait.
Is it worth spending extra money for the cracks in my driveway to be filled?
Cracks in asphalt may seem like a small problem at first but, left unchecked, they have the greatest destructive potential of all threats to your asphalt. When cracks are found, they should be sealed with a rubberized crack sealer. This practice will prevent water from breaking down the asphalt and the base layer beneath it.
Isn’t it much cheaper to seal my driveway on my own?
Products you can purchase in hardware stores are inferior and they are not cheap and often they don’t cover the square footage that is stated on the packaging. Some products are even made from recycled tires or are acrylic-based which are essentially paint and actually prevent the permeability your driveway needs. When you factor in the cost of doing it yourself – several containers of residential grade sealant, the roller, the brush, the pan and a stiff bristle broom – many companies such as Canadian Property Stars can provide a superior quality service for less overall cost.
What is the lifespan of an asphalt driveway?
A newly laid asphalt driveway can be expected to last anywhere between five and fifteen years if not properly maintained. However, with an annual or bi-annual application of seal coating, that very same driveway can be expected to last anywhere from fifteen to thirty years. Now there are obviously several factors such as climate variance and traffic patterns that play into asphalt longevity but it is accepted that an annual seal coating is the number one factor in extending the overall lifespan of the asphalt.
If asphalt driveways are so susceptible to deterioration, why are they installed by builders?
For the Canadian climate with its extremes of cold and hot, asphalt is the ideal material for a durable and long-lasting driveway.