Published on 04/15/98

Don't Invite Tree Roots into Your Home

The weather is warm and rain abundant, and tree roots are trying to break into your house.

For most well-designed and -installed foundations, sidewalks and driveways, roots can't breach your spaces. But some poor designs actually encourage tree roots to grow, leading to structural damage.

We're surrounded by a hardscape of cement, masonry and asphalt. Within this hardscape are sewers, water pipes and utility lines that bring quality to our lives.

These hardscapes are built to withstand occasional natural calamities and constant use by humans and vehicles. But they're sometimes vulnerable to other natural attacks.

Many sidewalks, driveways, patios and foundations are designed and installed properly for human use but ignore the valuable trees in the area. They aren't designed to withstand slow-acting natural processes. And opportunistic tree roots use these engineering flaws.

Many homeowners and engineers blame tree roots for cracking sidewalks and damaging foundations. Irreplaceable trees have been permanently damaged or removed to minimize damage to a piece of concrete. But the trees are just the scapegoats for faulty design, engineering and maintenance.

We often invite tree roots into the hardscape surrounding us. The ways we design and build things leave gaps, pores and spaces for tree roots to use.

The coarse sand beneath a sidewalk is an open invitation for roots to grow and crack the cement. Without proper soil compaction or protective barriers, roots will colonize areas near pipes, foundations and pavements.

Roots aren't the main cause of damage to hardscapes. Through careful disregard, their roots are invited into warm, moist, protected places with plenty of oxygen and space.

With a full cookie jar left open in the play room, a child may be blamed (or even punished) for cookie indiscretions. But better solutions are clearly present.

Tree roots are made to use soil pores and control space. Providing more space for root systems is the same as providing more resources for the tree. Roots are designed to carefully sense current soil conditions and, in concert with the rest of the tree, exploit open spaces.

As roots explore and colonize soil space, they come into conflict with other structures. These conflicts are most often associated with sewer or septic lines, storm water drains, water supply lines, foundations, sidewalks, streets, parking lots, pavements (floating and with footings), curbs, walls, swimming pools and structures on dimensionally unstable soils.

Most of these conflicts are preventable.

If we understand trees' growth and correctly install structures made of proper materials, we can minimize tree root damage. Ignoring the way tree roots grow will allow trees to remain an excuse for poor workmanship, bad development, ignorant designs and incompetent engineering.

Tree roots take advantage of cracks, pores and gaps in building materials. They can't push into pipes. But they can take advantage of small cracks and improperly sealed joints and connections. They can't break up cement. But they can raise pavements where foot traffic can form cracks. Tree roots can't grow into a solid foundation. But they can grow into settling cracks caused by other problems.

Some tree-illiterate designs inadvertently prepare a great home for tree roots. When the roots move in and start to elongate and grow in diameter, any fault can be expanded.

Don't blame trees for human errors. If you don't want tree roots, don't invite them in.

Kim Coder is a forester with the University of Georgia Warnell School of Forestry and Natural Resources.