Can tree roots damage a foundation? A buyer's guide

Do tree roots near a house foundation cause damage?

Yes, but usually not on their own. Purdue University Extension says roots can damage a foundation "with an invitation to do so": solid concrete turns them aside, but they move into a crack that is already there. So a tree near the house is a reason to check, not proof of damage. Before your inspection deadline, have an arborist look at the roots, and a structural engineer look at the foundation if the report also notes cracks.

Key takeaways

• In clay soil, a thirsty tree can dry the ground under the house and cause uneven settling.
• An arborist's written report plus an engineer's visit typically tops out around $1,480, before any digging to expose the roots.
• Insurance usually won't pay for root damage after you move in, so price it now.

What does it cost to check and fix?

Kept prices every line of an inspection report for $79, usually under 4 hours, and marks lines like foundation movement as needing a contractor's figure.

All rows are national figures from HomeAdvisor, and a tree close to a house will likely cost more to remove than one in the open. Digging out the roots to look at them is extra: one homeowner who wrote to Purdue was quoted $500 by a certified arborist to expose them with an air knife.

Here is how it adds up. Say your report notes an oak close to the house and a crack in the basement wall. An arborist's report and an engineer's visit typically top out around $700 + $780 = $1,480, plus the root dig if the arborist wants one. Now say the engineer calls the crack minor and the arborist says the tree should come out. Crack sealing plus removal is typically up to $800 + $2,000 = $2,800. A very large tree can push removal to $5,000, which brings the total to $5,800. These are national ranges, not caps, and local bids can run higher. Because the tree sits close to the house, use the tree company's written bid over the table. If the engineer finds the foundation moved, the number is the engineer's scope priced by a contractor's written bid.

How do tree roots cause foundation problems?

Roots grow where growing is easy, like loose soil and mulch. Purdue says they normally stay shallow, but when they reach the looser backfill soil beside a foundation they can abruptly turn down. That can put them right against the wall.

Roots also cause trouble without touching the wall. The American Society of Civil Engineers' Geo-Institute, in its homeowner's guide to shrink/swell soils, says roots from trees next to or under a foundation can dry out the soil and cause uneven settlement. Clay loses volume as it dries, and the foundation settles with it.

Roots found in a crack don't prove they made it. A Raleigh, North Carolina tree company says the crack comes first, from water or shifting ground, and the roots get blamed when the wall is dug out.

How close is too close for a tree to be to a house?

The Geo-Institute's rule is to plant trees farther from the foundation than their mature height. A tree company in Eugene, Oregon plants new trees at least 15 to 20 feet from buildings, and it treats visible roots within 10 feet of the house as a warning sign.

Those are rules for planting new trees, not a verdict on a mature tree already closer. What the rest of your report says matters more.

How do you know if tree roots are damaging the foundation?

Look at what else your report says. The Geo-Institute lists typical signs of soil movement under a house:

• Stair-step cracks in brick or block walls
• Cracks above doors and windows, or at wall corners
• Doors and windows that stick
• Sloping floors, cracks in tile flooring, or cracks in a concrete floor 1/16 inch wide or more

The more of these signs a house shows, the more likely the foundation has moved. A tree note with none of them is a smaller question than a tree note next to a crack. Your home inspector isn't required to settle it. Under the American Society of Home Inspectors (ASHI) Standard of Practice, inspectors don't have to judge whether structural parts are adequate.

Two people answer it. A certified arborist checks the roots; Purdue says finding them may mean digging a foot or two down within a few feet of the wall. A structural engineer checks the foundation. Structural engineer inspection before buying covers that visit, and foundation crack on an inspection report covers the crack itself. How to get repair estimates during the inspection period covers getting both in time.

What should you ask the seller for?

Ask for the fix the reports name, priced by written bids.

• Roots at the foundation, tree staying: root pruning plus a root barrier. Purdue says cutting the roots should prevent future problems, especially with a barrier against regrowth.
• Tree coming out: removal by a tree company, priced by its bid.
• Crack or movement: the repair the engineer specifies.
• Work can't finish before closing: a credit sized to the bids, so you hire the contractors yourself.
• Past work on the tree or foundation: the invoices and any warranty paperwork.

What to ask for after a home inspection covers how this line fits your list, and the buyer repair request letter template covers the wording. Your contract sets the deadline and your options, so confirm both with your agent.

Is a tree near the foundation a reason to walk away?

Not by itself. A tree with no cracks, sticking doors or sloping floors is an arborist's call and maybe a barrier. The harder case is a tree next to a crack with no engineer's scope yet, because then you don't know the cost.

If the engineer's number is more than you can carry and the seller won't pay it, when to walk away after a home inspection covers how to decide. Foundation and structure findings lists the other structural lines to weigh with it.

Does homeowners insurance cover foundation damage from tree roots?

Usually not. Allstate lists nearby tree roots among the causes of foundation problems that are often not covered. Progressive says foundation cracks and settling generally aren't covered, and that keeping tree roots from damaging the structure is the owner's job. Read your own policy, but plan on this being your cost once you close.

How do I stop tree roots from growing under the foundation?

Hire an arborist, not a shovel. Purdue describes finding the roots by digging near the wall and cutting the suspect ones, sometimes down to the base of the foundation. The Geo-Institute says pruning only slows soil drying for a while. Where a tree stands closer than its mature height and the foundation moves with the seasons or droughts, it calls for a deep root barrier between the tree and the house.

Roots showing above the ground near the house are a different job. Purdue warns that cutting or grinding them out can hurt the tree, and removing large ones can make it unstable enough to fall in heavy winds. Its fix is 2 to 3 inches of wood mulch over them, with any root pruning done by a professional arborist.

How do I price the rest of my report?

Upload your inspection report to Kept so your days go to the arborist and the engineer, and the rest of your request goes in with numbers behind it.

Sources

• Purdue University Extension, Can tree roots cause damage to a home's foundation?
• ASCE Geo-Institute, Living With Shrink/Swell Soils: A Homeowners' Guide
• ASHI Standard of Practice
• HomeAdvisor, How Much Does an Arborist Cost?
• HomeAdvisor, How Much Does Foundation Repair Cost?
• Sperry Tree Care, Tree Roots vs. Your Foundation
• Leaf & Limb, Do Roots Cause Damage? Debunking Common Myths
• Purdue Extension, Surface Root Syndrome
• Allstate, Does Homeowners Insurance Cover Foundation Issues?
• Progressive, Does Home Insurance Cover Foundation Repairs?