How Do You Get Rid of Tree Roots Under Concrete?


We all rely on concrete foundations to stay strong and stable for us to stand on. There isn’t a lot that’s more terrifying than a crack in your foundation. Cracks in the driveway or sidewalk aren’t pretty, either.

We also all love trees, but their roots can sometimes run amok and cause damage to sidewalks, walkways, and even underground pipes and building foundations.

Tree roots can cause cracks when they grow through broken pipes or underneath a building or sidewalk and start to intrude into the space above them.

To get rid of tree roots growing in underground pipes or under concrete, use Foaming Root Killer and Polyethelene Root Barrier Panels. Foaming Root Killer goes into your first floor toilet to clear the pipes by making roots brittle. Then use the Root Barrier Panels by cutting intrusive roots and placing panels to block growth toward your concrete.

Clearing Pipes Before Roots Break Out and Escape

Using the Foaming Root Killer is a good first step if you have trees within 20 feet of your pipes.

For best results, flush Foaming Root Killer down your first floor toilet during the time of least usage. You want a 10-hour block of time for the foam to sit.

It will make the roots brittle so that eventually they will dissolve away. It will do this without killing the tree, as long as you don’t kill the roots too close to the tree itself.

Green Gobbler Foaming Root Killer is available from Home Depot for $20, a nice price to solve such a potentially expensive problem. The label claims it is safe on pipes, soil, and trees, when used correctly.

The makers recommend doing this flush each day for three days, and then again every two months, to prevent roots from growing back in the pipes.

This is important because if roots clog up your pipes, the pipes could burst, and then the roots will continue toward your foundation. Tree roots can get into your pipes even when the trees are planted twenty feet away.

If I’m making roots sound like malicious alien plants out to destroy your home, forgive me.

I personally love trees! That’s why I always plant my trees far away from the house, power lines, and any concrete. I don’t want to have to choose between our home infrastructure and a beloved tree.

Okay, so you’ve taken care of the stealthy roots in your pipes. Now to tackle the big problem.

Now For Serious Concrete Protection: Root Barriers

Cutting tree roots back and placing the Polyethelene Root Barrier Panels in front of them is more work, and more expensive than the pipe fix, at $90 for two feet of paneling (available at Home Depot).

It’s still less expensive than the cost to replace concrete, so the price of prevention is definitely well worthwhile!

My sister and her husband have been working on refitting a detached building on their property into a marketable B&B-worthy casita for guests. They’ll already invested a lot of personal DIY hours and money into gutting it, insulting the walls, creating an attic, and framing the rooms.

They’ve even done some of the plumbing themselves.

Their foundation is thick, but there is one part where the concrete has a crack, and they are wondering 1) how deep does the crack go? and 2) was it caused by tree roots from their nearby fruit trees?

It’s possible the crack is only superficial, and in that case, it’s just a matter of patching it up and finding the right flooring to cover it up.

If it was caused by encroaching tree roots, though, that’s a problem that will only get worse as the trees grow bigger and shoot out more roots.

Since the fruit trees are so close to the building, my sister and brother-in-law are going to want to dig down to the roots at least two feet away from the structure or concrete foundation. Then they’ll put in the polyethelene root barriers and bury them.

These root barriers need to be thick so they can do the job of diverting the roots properly.

Other Kinds of Root Barriers and Small Concrete Repair

Root barriers that look like thick garbage sacks might not do the trick for tree roots; they’re mainly for blocking the growth of weeds and grass roots. These thinner root barriers are a great idea for laying down underneath a new driveway or sidewalk.

If you already have tree roots coming up under the sidewalk or driveway, you’re going to have to replace the concrete. This means breaking up the concrete, releveling the ground, and pouring new concrete.

However, lesson learned, right? Make sure to bury root barrier panels at least two feet away next time, to prevent this happening again.

For grass and weeds coming up through the cracks in your sidewalk or driveway, try salting the cracks to prevent future growth.

If you’ve already got a nasty-looking crack in your driveway or walkway, or even a structurally complex area like your front steps, you can buy a Crack Weld Injection Kit. Use it like a caulk gun, and the material will chemically bond to the concrete, just as strong and structurally supportive. This fix will cost you $108 at Home Depot.

If your concern is mostly cosmetic, about how bad it looks, you can also get a bucket of Flo-Coat Resurfacer to make your concrete surface look smooth and new again for $27 at Home Depot.

Small repair might be all you have funds and willingness to do at the moment, but until you can lay down some barrier and new concrete, it’s a good option.

The most important thing is to make sure you’ve blocked the roots to prevent further root-caused damage. Whether you use root killer first or cut and block with root barrier, you’ll want to be sure to take care of that problem first before repairing or replacing your concrete.

Now that you have a good idea what the price point is of each intervention, I hope you can develop a plan to deal with your particular challenge.

Yes, Trees Are Worth the Trouble

While trees can be disruptive when they grow too close to our infrastructure, they are beneficial in many ways.

Here are some of the major benefits we receive from trees:

  1. cooling temperatures in the heat,
  2. turning CO2 into oxygen worth breathing,
  3. offering shade for people and animals,
  4. providing leaf debris to replenish the soil,
  5. often giving fruits, nuts, or seeds people can eat,
  6. and blessing humanity with beauty that brings feelings of peace.

Yes, trees are worth all the trouble. Even when they struggle to stay in their lane. As with so many problems in life with plants, animals, and humans, all they need is firm boundaries.

Katrina Lantz

Katrina Lantz studies neuroscience at BYU. She is a curriculum developer at Ensign Peak Academy. She also writes under the pen name K.L. Lantz. Her published books include middle grade fiction: Drats, Foiled Again! and Bombs Away! and adult Christian inspiration: The Healing Bucket.

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