Do Root Barriers Work? How? Why?

Tree root barriers help to protect your hardscape – including sidewalks, curbs, and driveways – as well as your hardscape infrastructure and landscape, from being uprooted or damaged by tree root systems.

How Do Deep Root Barriers Work?

Over time, tree roots can grow wildly – expanding vastly and rather randomly – in unexpected or unpredictable ways. When this happens, they can cause significant damage to roads, driveways and sidewalks. Tree roots can also interfere with septic lines and cause drainage issues too.

Species of tree, climate zone, soil composition and water are just some of the elements effecting how tree roots will expand. The goal of a deep root barrier is to guide or force tree roots downward in an orchestrated manner, rather than allowing growth to occur haphazardly. Ensuring downward root growth helps to prevent the upheaval of roads and sidewalks by redirecting surface and lateral roots that undermine these structures.

Are Deep Root Barriers Effective?

There have been numerous studies examining the effectiveness of tree root barriers.

One of the most prominent was a Dutch study reviewing sixteen different root barrier treatments[1].

This study discovered that all 16 they looked at were fairly ineffective, with roots burgeoning to such an extent that they expanded out and up enough to break through the surface over time.

Thus, the Dutch study managers concluded that for a root barrier to work well, it needed to:

  • Be deep—ideally, extending below the primary root system
  • Protrude above the ground level slightly
  • Be UV resistant

How Do We Best Ensure the Effectiveness of Deep Root Barriers?

Additional reviews on the effectiveness of root barriers have come up with similar results and answers.

According to the author on shadetreeexpert.com, additional information gleaned includes:

  • Even if redirected roots resurface later, those roots tend to be smaller, weaker, and less intrusive.
  • Deeper root barriers are more effective
  • The root barrier should protrude above grade.
  • A compact soil backfill after root barrier installation has the root barrier in place is helpful/.
  • Using a gravel backfill under both hardscape elements and the root barrier might provide additional benefits.
  • Root pruning prior to installation of root barriers is likely to be beneficial.
  • The area below the tree’s drip line should be mulched with natural wood chips so that when they decay, they provide nutrients for the tree’s root system.

Are All Root Barriers Created Equal?

Clearly, not all deep root barriers meet the above criteria. The good news is that Sidewalk Shield meets them all.

Sidewalk Shield is made of recycled, HDPE plastic. It comes in rolls and three different heights/depths—18 inches, 30 inches, and 36 inches. The width is 2.0mm for the 18 and 30 inch and 2.5mm for the 36 inch. Because of its malleable composition, Sidewalk Shield can be used in straight lines or in a circular design.

Using Sidewalk Shield provides decisive direction for root growth. This allows the tree greater long-term health and allows for longevity of sidewalk and roads in adjacent areas. In addition, uplifted sidewalk and driveways can cause serious tripping hazards that can become liability issues. Installation of Sidewalk Shield directs the tree roots in a downward fashion to protect sidewalks, roads, trees, and ultimately people.

When you need a deep root barrier you can count on, you can trust Sidewalk Shield to do the job right.


[1] John Roberts, Nick Jackson and Mark Smith, Tree Roots in the Built Environment, Centre for Ecology & Hydrology, Natural Environment Research Council, London, 2006, p. 386.

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