How To Deal With Tree Roots Growing Under Asphalt

Just about anyone who has a driveway, parking lot, or uses a sidewalk is familiar with how tree roots can destroy asphalt paving. Tree roots can grow tens of feet away from the trees, and of course, they grow underground. Now asphalt is famous for being pretty tough, it takes a lot of punishment – that’s why it’s used as a surface for multi-ton vehicles to drive on. However, they are particularly susceptible to damage from below. Frost heave, expanding and contracting earth, and of course, tree roots, are very dangerous to asphalt.

If there is a tree growing near your driveway or parking lot, it’s a pretty good bet that it’s roots will get under your paving eventually. It can start simply, with the pavement becoming uneven. After some time, the dirt that the pavement is built on can buckle, like a small fault line, and cause the pavement serious damage. The pavement itself can collapse or develop enormous cracks from tree routes.

Fortunately, we are here to let you know the several ways in which pavement-destroying roots can be handled. Handling this problem can help the survival of your tree, and of course of your paving.

Plan ahead

Don’t pave by trees

An ounce of prevention is worth a pound of cure. The best way to avoid tree root damage to your pavement is to simply not put the pavement nearby trees. This surefire method will 100% guarantee that no tree roots will damage your property. 

However, that’s not always a great option. Maybe you want a shaded patio. Maybe your house already has trees on it and your driveway is just going to have to deal with roots. Either way, simply not building nearby trees isn’t always an option.

Don’t pave by young trees

If you have a lot of tall old growth trees on your property or business, it’s actually safer to build by them than it is by younger trees. The older trees have much slower growth, and they usually have an established root system. This means that there won’t be quick-growing roots breaking up your pavement over the course of a few years. Paving nearby young trees is much riskier. Small trees may seem harmless at first, but they grow quickly. A root system that starts small can get bigger and work its way under your asphalt in just a few years. Once the roots are underneath, they will continue to grow and do damage. 

Use a smart drainage system

Most asphalt paving is built on a very slight incline so that water doesn’t build up on top of it. Tree roots also have a tendency to seek out where water goes. If you are building your blacktop by trees, make it so that the incline goes towards them, that way the roots will go to where the most water is. If the incline is going down in the opposite direction of the trees, then the tree roots will cross under your pavement in order to get to the earth with the most moisture. Use a drainage system that will hopefully result in trees roots not crisscrossing beneath the paving.

Know how trees grow roots

Do your homework about trees. Know that roots can grow to the crown edge (diameter of the top branches/foliage), and plant trees an appropriate distance from your pavement or put your pavement the correct distance from your trees. 

Another option is to plant trees that don’t have surface-level roots, or trees that have smaller root systems that stay deep underground. 

Root removal

Digging and cutting

OK, so the root is becoming a problem and needs to go. What can be done about it? Manual root removal is the process of digging out the tree root and cutting it. It can be done with a shovel and a chainsaw or ax. Another option would be getting a gas-powered auger, digger, or small excavators. Most excavators you have seen are probably for construction sites, but small ones for trail building are perfect for root removal. 

Copper sulfate

The chemical way to remove damaging tree roots is copper sulfate. Copper sulfate is a toxic chemical however, so unlike digging and chopping the root yourself, you will want to have a professional apply this one. 

Although it is a dangerous and toxic chemical, copper sulfate is used because it does not travel far along the tree root. This prevents it from reaching the whole tree or other roots, and only kills the offending part of the root. 

Be careful with use of copper sulfate though, as overuse can contaminate the environment. Copper sulfate is a heavy metal that is toxic to microorganisms that treat sewage water.

Building a Barrier

After the root that’s been hurting your pavement has been handled, it’s time to set up some defenses. A root barrier can be established between the pavement and the tree. These barriers be physical, made from sheet metal, or some other substance that simply prevents the root from coming in. They can also be softer materials soaked in copper sulfate to create a chemical barrier. Of course, root barriers don’t always work, as persistent roots will definitely find a way over time.

Know what to do to keep the roots at bay

In general, in life, as well as paving, have a plan. If you have had to deal with root damage before, then be prepared for it again on your pavement. There is no substitute for regular maintenance and inspection. If you suspect tree roots are causing your pavement troubles, then that’s all the more reason to engage in preventative maintenance. Fortunately, Reliable Paving is here for you. We are paving contractors with over 35 years of experience, and we know how to install, rebuilt, repair, and maintain asphalt of all kinds. If you think tree roots are causing your parking lot some problems, contact us today, and we will see what we can do.