If you're curious to know "When is the best time to sealcoat an asphalt driveway or parking lot", we'll have to dive into more detail to help guide you to the answer you're looking for. It's a loaded question. For example, do you want to know the best time of day to sealcoat? Maybe you want to know the best time of year to apply an asphalt sealer? There are also the topics of "when is the best time to re-apply a sealcoat sealer", or maybe you want to know "how long you should wait before sealing a freshly laid asphalt surface"? Hopefully, you can see it's a bit difficult to directly answer the question "When is the best time to sealcoat" because it all depends on what you're ultimately trying to accomplish. Don't worry though, we'll walk you through each scenario and hopefully nail down the answer for you.
What is the best time of year to sealcoat an asphalt driveway or parking lot?
In general, summertime is the best time of year to sealcoat asphalt because the ambient temperatures in many places are high and relative humidity is low. Temperature and humidity are huge factors in how long it takes for asphalt sealers to dry and fully cure, so the summertime isn't necessarily the rule of thumb either, but it's usually a great time of year to sealcoat.
It's best to understand what type of asphalt sealer you're dealing with because it will help you gauge whether you want to sealcoat in warmer weather, or if you can get by in cooler weather.
Water-based asphalt sealers such as asphalt emulsion, coal tar, or hybrid sealers, must all be applied when the pavement temperature is no lower than 40º F. Since they are water-based, they are prone to freezing, and whenever water-based sealers freeze, it alters their properties and permanently damages the product. That's why the wintertime is completely out of the question for many places because you can't sealcoat in freezing weather. The only exceptions to this rule are Gilsonite and "Oil" Sealers which are solvent-based sealers. You can apply a solvent-based asphalt sealer at any temperature you're willing to be out in. (Regarding "Oil" sealers, most asphalt emulsion sealers are water-based oil sealers, but when people refer to an "Oil" sealer, they're usually referring to the solvent based version.)
The main reason we suggest the summertime for sealcoating is because of the quick cure times the warmer weather brings. Most folks don't want to wait more than 24 hours for their driveway to fully cure and if you own a business with an asphalt parking lot, you certainly don't want to wait more than 24 hours. The warmer the weather and the less humidity in the air, the faster the sealcoat will dry to traffic, and the faster it will fully cure. If you sealcoat on a 50-degree day, you might have to wait 48 to 72 hours before the sealer is fully cured.
Keep in mind that fully cured and dry to the touch or dry to traffic, are very different stages in the drying process. Dry to the touch means you don't get anything on your finger if you touch it, however, the weight of a car might cause areas of sealer to pick up on the tires. Dry to traffic means that the weight of the car won't cause pick-up on the tires, but if you turn the tires too sharply, it might end up "tracking" or causing tire marks. Fully cured is fully cured which means you're safe to walk and drive on it without worrying about messing things up.
Weather Conditions
If at all possible, it's recommended to sealcoat when you know you'll have some good sunshine to help warm and evaporate the liquids within the sealcoat sealer. If you pick a day that's cloudy, that's OK, just as long as you know you won't have any rain or moisture (including fog) for at least 24 hours or more. We had a customer write in some kudos about our BIG A sealcoat sealer holding up really well after some rain hit six hours after they put it down. We sell some pretty good stuff that can hold up, but seriously, if you can wait for the days without rain in the forecast, do it.
The folks at Professional Pavement Products, Inc put together a really cool tool at DAFScale.com that will check the weather, then tell you if it's recommended to sealcoat that day and all the way up to 36 hours later. It gives weather conditions and shows a forecast that is a dummy-proof indicator whether you're in the green, or red when it comes to sealcoating at the time of day you plan to get started. Not sealing for a few days after you get material? No worries. Check the site a day before you plan to start and make sure you're all clear. DAFScale is perfect for both homeowners and business professionals. Contractors and city crews love checking DAFScale every morning to make sure they're good to go for the day and you can too for free!
Watch Out For Shade
One thing to take into consideration when sealcoating, is the amount of shade that the pavement will have. Direct sunlight will always cause the sealer to dry faster, than shaded areas. Let's say that starting at mid-noon all through the afternoon and evening, one portion of your driveway will be covered by shade. This isn't a problem, but it does take longer for the sealer to dry. You might consider sealing earlier in the day so that the shady area has a chance to dry faster before the shade hits. If your entire pavement area is shaded, you'll just have to deal with it. Maybe the shady area only happens in the morning. You could wait until the afternoon when it isn't shady.
Shady areas aren't a big deal, but if you want the fastest dry times possible, make sure the sealer has plenty of direct sunlight to help it dry faster.
So, now that you know the best time of year to sealcoat (when it's reasonably warm), you're probably wondering when is the best time of day to sealcoat and an educated guess would probably be the afternoon… Let's find out!
When is the best time of day to sealcoat an asphalt driveway or parking lot?
As a general rule, there's no set time of day that is best to sealcoat. You can ideally apply a sealcoat sealer at any time of the day and be just fine, as long as the pavement temperature isn't going to dip much past 40º F at night. Yes, you can even sealcoat at night if you want. Yes, sunny days will help sealer dry faster, but if you're limited to a particular time of day, get it done because it doesn't really matter. Just understand that if fast dry times are important, daytime might be better.
Homeowners
What we suggest for the time of day you choose to apply asphalt sealers, really all depends on your needs. For a homeowner sealing a driveway, you might prefer to wait until 10am when the sun is beginning to get high, temperatures are still tolerable and humidity is starting to go down from the morning dew. Maybe 8am suits your taste. That's fine too. Just remember that most of your sealers need 24 hours of full cure time, so if you start at 8am, you won't want to allow traffic for a while. If you start early in the morning, you might be fine to park the cars by evening. Maybe you'd rather wait until you're off work during a weekday. That's fine too as long as you don't mind parking the cars in the street or the wife doesn't randomly decide she wants to go on a late-night shopping spree with cars in the garage.
Choose a time that is best for your schedule and pick a day when you know you won't have to deal with moving cars around.
Businesses
If you're a business owner wondering when the best time of day is to sealcoat your asphalt parking lot, the same rules apply. It really doesn't matter. That said, a lot of businesses will have their parking lots professionally sealed at night time because it allows plenty of time for the sealer to dry enough to allow traffic. This keeps you from having to shut down your parking lot during business hours. Ideally, the best time for businesses is early to late evening, but the decision is entirely up to you. Maybe you're not open on the weekends, so a Saturday or Sunday afternoon will work best.
How long should I wait before reapplying a sealcoat sealer?
This is a two-part answer because we need to determine if you're talking about a second coat for the current job or a whole new coat down the road.
If you're wondering how long you should wait to apply sealer for a second coat, the rule of thumb is generally once the sealer is dry enough to walk on, without picking up on your shoes. Second coats are generally needed for very old asphalt that hasn't ever been sealed before, or you might need a second coat for extremely rocky or porous asphalt aggregates. If you planned for one coat and decide you need a second, you can easily apply it as soon as you pick up the new batch of sealer. A week or two won't hurt anything.
If you're wondering how long you should wait before you sealcoat again, it really all depends on how good the sealer was that you applied. You could reseal every 3 months if you really wanted to, but that would get pretty expensive. In other words, there's no set time to wait before you reseal.
Some sealers only last 6 months. There's a lot of folks who complain about the $20 box store sealers only lasting about 6 months to a year. If that's the case, you're re-sealing every 6 months to a year. But if you have a good asphalt sealer like our BIG A Asphalt Sealer or BIG A Coal Tar sealer, you should easily get a minimum of 1 year, but most of the time, easily 2 years. If the sealer has worn down and it looks like it needs to be resealed, it probably needs resealing. But as a rule of thumb, if the sealer still looks good a year or two later, you can probably wait.
If you see flakes or chips of sealer a year or more after sealing, you applied the sealer too thick, and it's advised to use a pressure washer to blast off as much of the overage as possible so you can go ahead and reseal the entire driveway or parking lot. Applying too much sealer is pretty common when using a squeegee, especially around edges, curbs, or car stops.
How long should I wait to sealcoat a driveway or parking long after new asphalt was installed?
Asphalt needs time to cure. Asphalt binders are made of either natural bitumen or synthetic asphalt, both of which come from oil. When fresh asphalt is put down, the oils within the binder, need to be washed away and cured by the heat of the sun, before you can apply a sealer. If you seal too early, the oils will mix with the sealer, causing the sealer to flake and crack.
Typically you want to wait a minimum of 6 months before applying sealcoat to fresh asphalt to give it time to fully cure, compact and settle. You might be able to get by with less time in some cases, but 6 months is usually the absolute minimum as a rule of thumb.
Just to err on side of caution, we recommend that you wait between 6 months and 1 year before applying a sealcoat sealer on new asphalt. Again, you can probably get by with less time in most cases, but even after a year, you won't have to worry about the asphalt degrading by UV light and weather to cause any concerns.
Cold Weather and New Asphalt
One thing to think about when having new asphalt put down, is the winter weather. This only applies to colder states, so if your area never reaches freezing temperatures, you don't have to worry. New asphalt can sometimes be rather porous or "holy", depending on how well it was compacted, the amount of asphalt binder used, and the size of the aggregate. Newly installed asphalt that is porous, "can" cause problems during the winter months if it isn't sealed before you get ice and snow. The moisture will find its way into the crevices, freeze, and then expand, causing it to break apart the asphalt surface. If you have a poor substrate, you might end up with premature cracking. To help with this, you will want a good sealer put down before the first winter hits.
So, if we recommend 1 year, but ideally you need a minimum of 6 months, you wouldn't want to wait until October to have new asphalt put down because you aren't going to be able to seal it in time for the cold moist weather. Plan your new asphalt installation accordingly so you will have plenty of time to allow the asphalt to cure before you seal it.