Does Rain Affect New Asphalt Driveways?

Asphalt driveways have many benefits for homeowners but two major inconveniences are the drying and curing processes. 

Effective drying and curing is essential to ensure the longevity of your new asphalt driveway, and complications during this initial period can result in cracking or a loosening surface, that can significantly shorten the lifespan and aesthetic appeal of an asphalt driveway.

Given the importance of this process it is hardly surprising that rain is a major concern when it comes to freshly-laid asphalt. In this article we’ll discuss how rain affects your new asphalt driveway, and what can be done to minimize the dangers.

Why Is Rain So Dangerous for New Asphalt?

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Does Rain Affect New Asphalt Driveways?

Heavy rain can have a number of deleterious effects on freshly-laid asphalt. Some of the most common issues are:

Delays Drying & Curing Time

A freshly-laid asphalt driveway cannot be immediately walked or driven on. Instead it requires time to dry out and reach the required consistency where it is strong yet flexible. 

A central part of this drying process involves the evaporation of excess water after laying. 

As should be obvious from this, additional water being added to the surface can significantly delay this time. This can be frustrating as you’ll be left just staring at your unusable driveway, willing it to dry out properly so you can stop parking your car on the road. 

Washes Away Oils and Salts

Think of tarmac as a very precise recipe. The drying and curing process is akin to putting that recipe into the oven to gently bake to perfection. 

Heavy rain soon after laying the driveway is like suddenly adding a load of extra random ingredients to the mix just before baking. It just messes up the whole balance, and risks ending up with something quite different to what you intended. 

Heavy rain can wash out the oils and salts that are crucial for a successful drying and curing process, or can water them down, causing them to be less effective. 

Leads to Expansion & Contraction

Asphalt is a permeable surface. This means that water can soak into it. This is most likely after heavy rain, where puddles may form on the surface, slowly soaking into the surface. 

Arguably the most damaging impact of heavy rain is that the rain is the damage it can do as it expands and contracts within the asphalt itself. This unbalances the structural integrity of the driveway and can result in cracks appearing in your driveway, or chunks of the surface flaking off like sunburned skin.

Clearly this isn’t ideal and may require some expensive and frustrating remedial work. 

How Long Does Asphalt Need to Dry Before Rain?

Ideally a freshly-laid asphalt driveway should be allowed to dry for at least 12 hours before rainfall is expected. Of course, the longer the time the better. In general an asphalt driveway will have dried enough after 2-3 days to be safely walked on, at which point rainfall will do less damage. 

Even under these circumstances, however, rain can still be a risk until the driveway is properly cured; a process that can take 6 months or more. 

And even then enough rain, particularly when it pools in great enough volumes, can cause issues.

The key message is that the sooner it rains after pouring your asphalt driveway, the bigger the negative impact is likely to be.  

How to Avoid Rain Damage to a New Asphalt Driveway

If rain is such an issue for a new asphalt driveway then it’s worth bearing in mind the following handy hints to minimize the risk to your beautiful new drive.

Check the Weather Forecast

The most obvious first step is to keep an eye on local weather conditions. While the subsurface layer can be worked on during inclement weather, it’s worth only pouring the surface layer when you’re guaranteed a day or two of dry weather. 

Consider the Time of Year

Winter is generally not the best time to be laying a new asphalt driveway due to the rainfall experienced at that time of year. Instead wait until the worst of the rainy weather is behind you. While this may be frustrating if you’re desperate to get started on your new driveway, in this case your patience will be repaid with a much nicer end result. 

At the same time, asphalt that dries out too quickly can be a problem in the height of summer, in which case it may be necessary to gently wet the driveway as it dries and cures. If the process of drying happens too quickly then the impact can be just as bad.

As a result, arguably early summer (before the heat gets too intense but the rainy season is over) and fall can be the best time to lay a new asphalt driveway with a minimum of fuss. 

Install a Drainage System

Asphalt driveways are easily compromised by excessive rain at any point in their lives. As a result, installing a drainage system makes a lot of sense. While it will add to the overall cost of installation, it can make for a worthy long-term investment. 

The point of the drainage system is to quickly wick away excess rain so that it doesn’t soak into or sit on your asphalt driveway. It can be sent either to an underground soakaway or straight into your mains drain instead. 

Remove Pooling Water

Puddles on the surface of your asphalt driveway should be avoided wherever possible. Sadly, slight undulations in the asphalt surface are quite normal, giving rain somewhere to gather.

Hopefully your drainage system will have helped to resolve some of this rain. At the same time, if you find puddles growing on your new driveway then consider using a yard brush to move it off the driveway and onto the garden. 

Be careful on very recently-laid asphalt though – you won’t want to risk damaging the uncured surface with a stiff brush. In these cases you may need to consider a more gentle solution, like using towels etc. to soak up excess moisture for the first few days.  

Keep Some Tarpaulins on Hand

Tarpaulins can be handy for temporarily covering a new asphalt driveway should rainclouds suddenly roll in unexpectedly. They can be draped across the surface and weighed down with bricks. 

The tarpaulin can therefore bear the worst of the rain, and any rain pooling on the tarpaulin can be gently tipped off.

Just be mindful that you shouldn’t walk on a new driveway for the first few days after laying. You’ll therefore need to consider how you’ll cover the driveway without stepping on it. In many cases this will involve two or more family members gently taking a corner each and stretching it out over your driveway. 

Seal When Possible 

Lastly, and thinking slightly longer term, sealing your asphalt driveway after it has dried can help to reduce water ingress. While you should be mindful not to seal the surface too soon (thus locking in moisture that needs to escape during the drying process) you also won’t want to leave it too late. Follow the instructions on the tin carefully to ensure you seal your asphalt driveway at just the right time.