Sealcoating – 5 misconceptions and realities

Sealcoat is a wonderous thing. Typically between ten and thirty cents per square foot, it’s an inexpensive way to turn a tired and gray parking lot or road into a striking and attractive black beauty. We’ve found that there are a number of widely held misconceptions about sealcoating. Here they are, in no particular order.

Seven year old pavement. The left side was sealed at year two. The right side was sealed after this photo was taken. The application on the left side at year two improved the appearance level, but ended up being unnecessary to protect the new asphalt.

Misconception — A brand new asphalt surface needs to be sealcoated right away to “protect your investment.”

Reality — Sealcoat replenishes the top layer of oil to prevent the asphalt from becoming brittle and it prevents and combats raveling (fine aggregates coming loose from the surface). An entirely brand new asphalt surface needs neither. We typically recommend that the surface be sealcoated before the first signs of raveling (loss of fine aggregate from the surface), which is usually anywhere from 3-8 years from new. The timeframe will depend on how much traffic, sunlight, and water flow there is on the asphalt.

Best advice — Simply re-stripe the markings on the asphalt after a few years if sealcoat isn’t necessary yet. It’s extremely inexpensive and will provide a nice aesthetic improvement.

Additional note — Often it makes sense to have repairs and sealcoating on the same cycle for mostly aesthetic reasons. The fine aggregates on the joints of the patch repairs do benefit from the sealcoat application and the entire surface ends up looking the same. Truth be told though, those patches would last just as long without a sealcoat – they just wouldn’t look as good.

Cracks, poorly constructed repair joints, and surface imperfections are still visible soon after sealcoating is completed.

Misconception — Sealcoat will fix cracks and “buy time” for replacement.

Reality — Sealcoat is a surface treatment only. It is not a flexible material and has no structural strength. As soon as the first vehicle passes over those sealcoat covered cracks, the sealcoat itself cracks and allows water back in to compromise the integrity of the base which contributes to further structural damage. While a sealcoat will improve the appearance of asphalt with structural damage, it will do nothing to make the asphalt last longer.

Best advice — If the pavement needs full rehabilitation, consider saving money toward that end, rather than using it toward a sealcoat even if it means the pavement may look worse for some period of time. If you do decide to sealcoat distressed pavement, make sure stakeholders have a clear understanding of its limitations.

Despite proper, regular maintenence in the form of slurry seals and sealcoats, this road is 25 years old and has reached the end of its useful, structural life.

Misconception — Sealcoat “extends the life of the asphalt.”

Reality — A better way to say this is that it allows the asphalt to have the full life it should, which is typically 20-40 years. We’ve seen asphalt falling apart from the top down due to a lack of sealcoating even though it was only 10-15 years old. With only one sealcoat application, the condition could have been prevented and the asphalt lasted another 10-25 years. On the other hand, we’ve had customers tell us they expected their asphalt to last forever because they’ve sealcoated it regularly! The sealcoating will have protected the surface, but done nothing to revitalize the oil holding the rocks together within the asphalt itself. Eventually the effects of age catch up with it.

Best advice – Make sure your reserve study or long-term planning does not assume an asphalt life longer than 40 years, no matter how much sealcoating has been done.

Cracking as a result of too much sealcoating.

Misconception — There’s no such thing as “too much sealcoat.”

Reality — There is indeed and it’s a huge problem! We’ve seen asphalt surfaces in great structural and surface condition where owners, managers, or boards have been a bit overzealous in their quest for proper maintenance and a smooth, black surface. Eventually the thick layers of sealcoat start to crack and peel (see photo). The only solution to this condition is to replace or overlay the asphalt (or in some cases, put a slurry seal on it, which is not always possible or desirable). Regardless, fixing asphalt that has been over-sealed is an expensive proposition. And more sealcoat would simply make the problem even worse.

Best advice — Look closely at the asphalt. You can’t see individual rocks in surfaces with many layers of sealcoat on them. Also look for the unique jagged, hairline cracks in the sealcoat itself (see photo for an example). If over-sealing is becoming a problem, the surface may simply need to be allowed to wear for a few years. In other cases, it may be possible to vary the application rate, placing one thin coat with latex over thick areas and two coats over worn asphalt and new repairs. We’ll always help out by letting you know if over-sealing might be becoming a problem and will offer ideas towards a solution.

Sealcoating would have prevented this extensive raveling and erosion.

Misconception — Sealcoat does nothing for surface preservation and is just a useless “paint job.”

Reality — Knowledgeable skeptics point out that asphalt does not need to be sealed until ALL of the previous seal has worn off in a given area. This is true. In addition, some roadways and parking lots get so much lightweight vehicle traffic that the rolling action of rubber tires kneads the asphalt, moving the oils through it and keeping it alive and well. But many owners re-seal their asphalt proactively on a 4 to 7 year cycle instead of waiting until all of the previous application has worn off. The seal can start to look “streaky” as it wears because the wear is inherently uneven — some areas are exposed to more traffic and water flow than others. Because the sealcoat really needs to be applied to the entire surface to look right, this means some of the areas with lesser wear are getting sealed before they truly need it.

Best advice — Let us help you plan your maintenance cycles so you’re protecting the areas in greatest need while not risking “over-sealing” areas that are not exposed to a lot of surface wear.

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