Do you want to create a lovely yard, but planted trees have too many roots which break the sidewalk or even cause foundation problems? Fortunately, there’s a way out. The article tells you about tree root removal under concrete.
Methods of tree root removal under concrete
1. You must ensure that the stump is removed since, in most situations, the tree’s roots will regrow if you do not. It’s easy to get rid of it by shredding it. Shred the tree stump to a depth of 12 inches to ensure that the whole stump is removed. Plant the stump as soon as possible after shredding it.
2. Hire a concrete contractor if removal isn’t a possibility. Concrete contractors (or one contractor) you choose will have a significant influence on the outcome of your sidewalk repair or replacement.
The following are some good methods:
Place a layer of gravel beneath the new concrete for root growth.
Reinforce the concrete with rebar so that the roots have to lift many concrete sidewalk slabs at the same time to cause any damage to happen.
To give the tree’s trunk and roots freedom to develop, build a pathway that curves or slopes around it.
Can you cover tree roots with concrete?
You are free to do so, but it’s bad for the tree so don’t. Concrete-encased tree roots are unable to absorb water, oxygen, or nutrients. Professional concrete workers, on the other hand, rarely pour concrete straight on bare ground or roots.
There isn’t much that can be done if the concrete was put right on the earth and tree roots. The concrete should be removed and a sturdy pavement built in its place. This should ideally not be done at the tree’s root zone. Even if the damage has already happened, be sure to remove the concrete from the tree roots.
You can place the concrete near the tree as long as you leave adequate space for tree root growth and the tree’s nutrient supply is not harmed.
How do you cut tree roots under pavers?
1. Remove all paving stones affected by the tree roots and enough rows to allow good access to the soil around the problem roots. Pry the paving stones from their substrate with your gloved hands, a spade, or a pry bar.
2. Number the pavers with chalk, if necessary, so you can replace them in a specific pattern. Place the pavers in a location where they will be protected from damage.
3. Dig out around the roots and remove the substrate from under the pavers and the soil around the roots. Remove enough soil to expose and clearly see the entire section of the tree root system you want to remove.
4. Cleanly sever the unwanted roots with a sharp cutting tool. A spade can be used to cut through small roots less than 1/2 inch in diameter, loppers can be used to cut through roots up to 3/4 inch thick, and a small ax is best for larger diameter roots.
5. Pull all root sections out of the soil and discard them. Make sure that the remaining roots all fall below the surrounding soil surface.
6. Backfill the excavated area with the previously removed topsoil to level the area with the surrounding soil.
7. Cover the soil with a layer of the substrate you will use to lay the pavers, usually gravel or sand, and level it to a smooth surface.
8. Lay the pavers in the desired location and tamp them down with the wooden handle of your spade or a rubber mallet.
9. Brush or wash off any chalk marks on the pavers and fill in the spaces with the remaining sand or aggregate, if applicable to your installation.
What to do when your tree’s root growth is destroying the sidewalk
Move the repaired sidewalk a few feet away from the tree, ideally outside the root plate, i.e. at a distance equal to three times the tree’s diameter.
Excavate beneath the offending roots:
Instead of cutting the roots that have elevated the sidewalk, leave the root intact and remove the dirt beneath the root with an air excavator such as an Air Spade or an Air Knife.
This space under the root can be left open or filled with clean gravel that will be pushed out of the way as the root develops lower. The root should spread downward and fill the space as you replace the asphalt sidewalk above it. This approach should be used in conjunction with reinforced sidewalks and other possible solutions.
Use thicker concrete:
If you increase its thickness from 4 inches to 6 inches, the sidewalk is less likely to crack or lift. This technique should be used in conjunction with the reinforced concrete technique described above for best results. Research is currently being conducted to determine the best concrete thickness. However, no data is available at this time.
Place the sidewalk over a flowers and gravel area:
Recent research on roots and sidewalks has shown that a geogrid placed on the roots spreads the force of the upward pressure of the roots over a large area. If we then cover the geogrid at least 3 to 4 inches deep with clean #57 stone, the concrete sidewalk can be poured onto the stone.
The stone should be covered with a geotextile fabric to prevent sand and soil from penetrating the stones. The stones provide a partially flexible buffer that distributes the force of the lifting roots to the concrete sidewalk slabs above. This arrangement may result in the sidewalk being higher than the original sidewalk.
Place clean gravel under the sidewalk:
Recent research has shown that simply placing clean gravel under a sidewalk slab will make roots spread under the crumbly material rather than directly under the concrete slab. The large air spaces in the material make the roots grow under the foundation.
Consequently, the sidewalk is less likely to be pushed up by the roots.
Rubber sidewalks and pavers:
Rubber sidewalks, other flexible materials, and pavers make it possible to reduce repair costs by removing and replacing a root-damaged section of the sidewalk. However, the repair often requires cutting roots that are raising the sidewalk.
However, these materials do not solve the problem of what to do with a large tree root that is increasing in diameter. Other options may be needed to accommodate the large roots rather than cutting them.
How to stop tree root systems from damaging sidewalks
Start by planting the tree right from the beginning!
Tree roots are not only the foundation of a tree but also a transport system that brings water and nutrients to the interior of the tree. They extend about a foot to a foot and a half out from the trunk for every measured inch of trunk diameter, or about a foot above the ground.
So a tree 12 inches in diameter has roots that extend 12 to 15 feet in every direction! Imagine trees in a forest that are of different heights and widths, and imagine the intersections and the extent of tree roots!
Now imagine your apartment block and the potential impact on your sidewalk. Those roots are looking for water. Not that you want to suppress growth, but you can water longer and less frequently so that the water penetrates deeper into the soil rather than just hitting the surface layer.
In the first few years of a tree’s growth, water the roots deeply to encourage growth and good health. Watering more slowly will help the water penetrate deeper into the tree roots.
Once a tree is about two to three years old, you should also prune it while maintaining good watering. Pruning back branches that are not thriving or growing into the street is a necessary action. You can train the tree to some degree to redirect its growth path. You may need to obtain a permit from the city to trim street trees.
Trees planted along the sidewalk often require root pruning in conjunction with sidewalk replacement and other street improvement projects. Some tree species that tolerate root damage better are Norway maple, ginkgo, hackberry, hawthorn, cherry, and river birch.
Trees that grow more slowly are also potentially less damaging to sidewalks. Some of these trees are known to grow taller, but we will consider the width of your sidewalk, distance from the street, power lines, and house to make the most important recommendation.
Since removing trees defeats the purpose of careful planning when planting a tree and may need to comply with local ordinances, it is important to take all possible precautions in advance.
While it may sound counterproductive to put a hump in the sidewalk, it is one way to avoid tree damage. The practice of pouring concrete over the damaged portion is called “bridging.”
This is often necessary when the roots are too large to cut and are now pushing up the original sidewalk. Another interpretation is more literal: you would actually build a bridge over the protruding tree roots.
Landscape pavers can also be used in these circumstances. Even though they are a different material, these stones can be adjusted to allow the roots to recede as they expand without damaging the entire sidewalk or requiring work.
There are a few other ways concrete can help keep your sidewalk from being damaged by trees.
Gravel can be placed under the sidewalk slabs to create air spaces between the soil and the sidewalk and to escape pushing up the slab in the process of root growth. This is not a foolproof method, but studies have found great success with this method. Pouring a thicker concrete slab can also prevent root systems from breaking through the slab.
A standard thickness is 4 inches, but increasing the depth to 6 inches can be a solution. If the roots begin to lift the sidewalk, it can be removed to level the surface again. Also, if the tree starts to push up the sidewalk again, this should give you several much-needed times to do pruning.
Also, using concrete reinforced with rebar or wire mesh will make the sidewalk more stable.
Options for sidewalk repair around existing tree species
1. Shaving the top of the concrete or installing a ramp to even the surface and reduce the tripping hazard
2. Increasing the distance from the tree to the edge of the sidewalk.
3. Bridging the pavement over the tree’s roots.
4. Replacing concrete with interlocking paver blocks or rubber pavers.
5. Root shaving then installing new concrete.
6. Root removal and lifted sidewalks replacement.
You should plant trees in the right spots so the tree will be protected whenever possible, tree roots are a very important part of a tree. Planning ahead and planting trees in proper good spaces will save you time in the future. If you plant a tree in a good spot, there will be no issues.
Resources for solving problems with the roots of sidewalks and trees
Dr. Ed Gilman, Trees for Urban and Suburban Landscape, Delmar, New York, 1996.
John Roberts, Nick Jackson and Mark Smith, Tree Roots in Built Environment, Center for Ecology and Hydrology, Environmental Research Council, London, 2006.
Smiley, Thomas, Bruce Fredrich, Neil Hendrickson, Ph.D., Tree Risk Management, Bartlett Tree Research Laboratories), Charlotte, NC, 2002.
Dr. L. Costello and Dr. C.S. Jones, Reducing Tree Root Damage to Infrastructure: A Compendium of Strategies, International Forestry Society Western Branch, Cohassit, California, 2003.
Dr. Ed Gilman’s website http://hort.ufl.edu/woody/urbansidewalk.shtml (accessed June 29, 2011)