Tree Roots in Your Foundation, Sewer or Driveway

Root problems arrive as a plumbing bill or a tripping hazard, which is why they get blamed for more than they do. Roots genuinely cause three recurring problems on Chicago-area properties - and they cause a fourth one far less often than homeowners assume.

Worth knowing which is which, because the fix ranges from a $400 pruning visit to a full removal.

What roots actually do

Tree roots are opportunists. They are not strong enough to break sound concrete or intact pipe. They grow where there is water, air, and a path of least resistance, and they thicken over years. Every real root problem is a version of that: a root found an existing opening, or a root got fat in a place something else was sitting.

Most of a tree's roots are also in the top 12 to 18 inches of soil, spread far wider than the canopy. They are shallow and broad, not deep and drilling.

Problem one: roots in the sewer line

This is the real one, and it is common in older North Shore and city neighborhoods with clay tile or cast iron laterals.

How it happens: a joint in old clay tile pipe seeps a little moisture. Roots find the seep, send hair roots through the joint, and then thicken inside the pipe where there is water and nutrients. Over a few seasons you get a root mass that catches everything flushed past it.

What you notice: slow drains, gurgling, repeated backups, and a plumber's camera showing a root ball at a joint 20 to 40 feet from the house.

The honest fix order:

1. Mechanical clearing or hydro-jetting. Opens the line immediately. Does not solve anything permanently - the roots regrow, typically within one to three years.
2. Chemical root treatment (foaming herbicide applied in the line by a plumber). Slows regrowth. Also temporary.
3. Pipe repair or lining. Fixes the actual cause, because the roots were only ever following the leak. A cured-in-place liner or a spot repair at the bad joint ends the cycle.
4. Removing the tree. Only worth it if the tree is also a problem for other reasons, or if the lateral cannot practically be repaired.

That order matters. Removing a tree does not remove the roots already in the pipe, and it does not fix the leaking joint that invited them. A neighboring tree, or the next one you plant, will find the same opening. If your only problem is the sewer, repair the pipe - do not start with the chainsaw.

Problem two: lifted walks, patios and driveways

Large structural roots near the trunk thicken year over year. A flat slab sitting over one gets pushed up, and you get the classic lifted sidewalk edge or the cracked driveway seam.

Options, roughly cheapest to most expensive:

• Grind or cut the high slab edge - cosmetic, but removes the trip hazard
• Replace that section of walk with a root-accommodating detail: a thicker slab, a flexible paver section, or a slight ramp over the root
• Prune the offending root, which is viable if it is a smaller root and far enough from the trunk. Cutting major structural roots close to the trunk destabilizes the tree and can kill it. A crew that offers to just cut whatever roots are in the way, with no discussion of trunk distance, is a crew to decline
• Remove the tree if the roots are clearly under the structure and the structure has to be rebuilt

The general rule of thumb used in the field: do not cut roots inside about three times the trunk's diameter from the trunk, and be cautious anywhere inside the drip line. Beyond that, selective root pruning is often fine.

Problem three: roots in a drain tile, septic field or window well

Same mechanism as the sewer: roots follow moisture into perforated pipe, which is designed to let water in and therefore lets roots in too. Drain tile around a foundation is a frequent victim. Treatment is the same logic - clear it, then fix the entry point or accept periodic maintenance.

Problem four: the foundation itself (mostly a myth, with one real exception)

Roots very rarely crack a sound foundation. What does happen:

• A root grows into an existing crack and widens it over years. The crack came first.
• In heavy clay soil, which the Chicago area has in quantity, a large tree drawing significant water in a dry summer can contribute to soil shrinkage near the house, and the soil swelling back in a wet season contributes to movement. Clay soils move with moisture whether a tree is there or not; a big tree close to the foundation can amplify the seasonal swing. This is a real, documented effect and it is also usually one factor among several - drainage, downspouts, grading, and the original construction all matter more than most homeowners expect.
• A trunk physically pressing against the wall as it grows. That one is unambiguous and it is a removal.

If you have foundation movement and a nearby tree, get a structural opinion before you get a tree opinion. Removing a mature tree in clay soil near a house can occasionally cause its own movement as the soil rehydrates. It is not a decision to make casually in either direction.

When the roots mean the tree goes

Removal is justified when:

• The trunk or major structural roots are inside the structure - foundation, walk, drive - and the structure is being rebuilt
• The root damage cannot be fixed without cutting roots the tree cannot survive without
• The sewer lateral cannot be repaired or lined along its route
• The tree has other problems anyway - decline, decay, a bad lean - and the roots are the deciding vote. See when to remove vs. save a tree

And when it does go, grinding the stump removes the root ball but not the whole root system. The remaining roots decay in place over following seasons, which is fine for lawn and relevant if you plan to replant in the same spot.

The cheaper move

Before authorizing a removal over roots, get two opinions: a plumber's camera on the actual line, and an arborist consultation on the actual tree. Half the root removals homeowners are quoted turn out to be a pipe repair and a pruning visit.

Root problems come up constantly in Evanston, Wilmette, Skokie, Morton Grove, and Niles, where mature street trees and clay-tile laterals share the same parkway. Use the online estimate tool for a range, or request a free on-site estimate for a straight read on whether the tree is the problem.