Tree Root in Your Foundation: What Happens

The short answer

A tree root growing into your foundation will crack concrete as it thickens, and the crack will widen over years, not weeks. Roots do not bore through solid concrete; they enter through existing cracks, joints, and gaps, then expand as the root grows. The damage is slow and cumulative, and it is usually repairable if you catch it before the crack reaches a structural width.

Roots follow water and weakness. Your foundation crack is both.

Most homeowners notice the problem when they see a crack in the basement wall, a floor that has become uneven, or a door that sticks for no reason. By then the root may have been working at the concrete for a long time.

How a root gets into a foundation in the first place

A root enters a foundation through a pre-existing crack, a cold joint, or the gap where a slab meets a wall. It does not need to break the concrete. If there is a gap of a fraction of an inch, a root tip can find it. Once inside, the root thickens. A root that is a quarter inch across this year can be an inch across in a few years, and that growth pushes the concrete apart.

Three conditions make this more likely:

• Soil that stays damp near the foundation, which draws roots toward the house.
• A crack or joint that was never sealed, which gives the root an entry point.
• A tree planted close to the house, which puts large roots within reach of the footing.

Roots also follow sewer lines and drainage. A leaking pipe under a slab can attract roots from several feet away, and the root will then work along the pipe toward the foundation.

What the damage looks like over time

Foundation damage from roots moves through stages, and each stage changes what you can do about it.

• 1 Root enters a crack or joint. No visible damage yet. The root is thin and the concrete is intact.
• 2 Root thickens. The crack widens. You may see a hairline crack become a visible line, or a basement wall start to bow slightly.
• 3 Concrete moves. Floors become uneven, doors stick, and cracks in drywall appear at corners. Water may start coming through the crack during heavy rain.
• 4 Structural movement. The crack is wide enough to admit water freely, and the wall or slab has shifted. This is the point where repair costs climb and the tree itself becomes part of the problem.

The timeline depends on the tree species, the soil, and how much water is in the ground. A fast-growing tree near a foundation can cause noticeable movement in a few years. A slow-growing tree might take much longer.

Can I just cut the root?

Cutting a single root can solve the foundation problem, but it can also kill or destabilize the tree, so the decision depends on the tree and the root. A large structural root that is cut can remove the tree's anchorage, and the tree may lean or fall in a later storm. Cutting a root also creates a wound that can let decay into the trunk.

If the root is small and far from the trunk, cutting it may be safe. If it is a major root close to the trunk, the better answer is often to remove the tree. The only way to know which situation you have is to look at the tree and the root together, in person.

If you cut a root, do not seal the cut with anything. Let it dry. And watch the tree for the next year for leaning or dieback.

When the tree has to come out

Removing the tree is the right call when the root is large, the tree is already leaning, or the foundation damage is advanced. Removing the tree stops new root growth, but it does not shrink the roots that are already there. Those roots will decay over time, and as they decay the soil around them can settle.

That settling is why tree removal near a foundation is not just a cutting job. The stump and major roots need to be dealt with, and the excavation has to be done without disturbing the foundation further. In some cases, the foundation repair comes first and the tree removal second, or the other way around, depending on which is causing the active movement.

We handle the removal side: cutting the tree, taking the weight off in pieces if it is close to the house, and grinding the stump. We do not repair foundations, and we will tell you when the foundation is the bigger problem.

What to check before you call anyone

Before you call, gather three things: the location of the crack or damage, the species and size of the tree, and how close the trunk is to the foundation. That information determines whether the job is a root cut, a tree removal, or a foundation repair that happens first.

Look at the crack. If it is wider than a credit card, or if the wall is bowed, treat it as structural until someone qualified says otherwise. Look at the tree. If it is leaning, if it has a cavity at the base, or if the root in question is larger than your forearm, the tree is likely the part that has to go.

If you are in Albany or the surrounding area and the tree is the part you need handled, call us at the number on this page. We will look at the tree and the root, tell you what the removal involves, and give you a written quote for the work. If the foundation needs repair first, we will say so.