Is My Tree Dangerous? A Homeowner's Assessment Guide

Every tree carries some risk—they're large, heavy objects that can fail. The question isn't whether a tree could fall, but whether it's likely to fail and whether it would hit something important if it did.

This guide helps you evaluate trees on your property. It won't replace a professional assessment for serious concerns, but it will help you know when to be concerned and what to look for.

The Two-Part Risk Equation

Tree risk has two components:

1. Likelihood of failure: How likely is this tree (or a part of it) to fall?
2. Consequences of failure: If it fails, what would it hit?

A tree with moderate problems over an empty field is low risk. The same tree over a bedroom is high risk. Both factors matter.

Signs of Potential Problems

Look at the Roots and Base

Heaving or lifting soil: If soil is mounding up on one side of the tree while the other side shows exposed roots or a gap, the root system may be failing. This is especially concerning if the tree has started leaning recently.

Fungal growth at the base: Mushrooms or bracket fungi growing at the base of a tree often indicate root rot. The visible fungus is just the fruiting body—the decay may be extensive. Large clusters or shelf-like brackets are particularly concerning.

Damaged or severed roots: Recent construction, trenching, or soil disturbance can damage roots. Trees may not show symptoms immediately but can fail months or years later.

Root girdling: Roots that wrap around the base of the trunk (instead of spreading outward) can strangle the tree over time and create a weak point.

Look at the Trunk

Cracks: Vertical cracks in the trunk indicate internal stress. Deep cracks that you can see into are more serious than surface checking. Multiple cracks or cracks that extend around a significant portion of the trunk are red flags.

Cavities and decay: Holes, soft spots, or visible decay indicate internal rot. Trees can survive with some decay, but extensive hollowing compromises structural strength. Tap the trunk—a hollow sound over large areas suggests significant internal decay.

Cankers: Dead, sunken areas on the trunk where bark is missing or abnormal. Cankers indicate disease and can weaken the trunk structurally.

Leaning: Many trees grow at an angle naturally and are stable. Concerning lean is:

• New or progressive (tree was upright before)
• Accompanied by heaving roots on the opposite side
• Getting worse over time
• Associated with visible trunk cracks

Previous damage: Old wounds that never healed properly, topped trees that regrew with weak attachments, or damage from vehicles, lightning, or construction can create ongoing structural weaknesses.

Look at the Branches and Canopy

Dead branches: Every tree has some deadwood. Concerning deadwood is:

• Large branches (4+ inches diameter)
• Located over high-use areas or structures
• Hanging or partially attached ("hangers")

Weak branch attachments: Where branches meet the trunk or other branches, look at the angle. V-shaped junctions with bark growing into the seam (included bark) are weaker than U-shaped junctions. Codominant stems (two trunks of similar size) with tight V-crotches are common failure points.

Overextended branches: Very long, horizontal branches with heavy end weight can fail, especially under ice or wind load. If branches are sagging significantly, they may be under stress.

Sparse or abnormal canopy: Significant leaf loss, wilting, or dead sections in an otherwise green canopy indicate problems. This could be disease, root damage, or other stress.

Environmental Factors

Exposure

Trees at the edge of a group (recently exposed by removal of neighboring trees) or on hilltops experience more wind stress than protected trees. Trees that grew in a forest and are now standing alone may not be adapted to handle wind on all sides.

Soil Conditions

Saturated soil after heavy rain reduces root anchoring. Trees are more likely to uproot in wet conditions. If your area has been unusually wet, be more cautious.

Recent Changes

Has anything changed recently?

• Construction or grading near the tree
• Removal of nearby trees that provided wind protection
• Changes in drainage or water table
• Significant pruning or damage

Trees can take years to show stress from root damage or environmental changes.

What's in the Target Zone?

The target zone is everything within falling distance of the tree. Consider:

• Structures: House, garage, shed, neighbor's house
• High-use areas: Driveway, sidewalk, patio, deck, play area
• Vehicles: Where cars are regularly parked
• Utilities: Power lines, gas meters
• People: How often are people in the fall zone?

A tree with problems over an empty lawn is lower priority than the same tree over your bedroom. Risk is about consequences, not just likelihood.

When to Call a Professional

Get a professional assessment if you observe:

• Any signs from the lists above, especially in combination
• A tree near a structure or high-use area that you're uncertain about
• Recent changes in a tree's appearance or lean
• Damage from a storm, even if the tree is still standing
• Any gut feeling that something isn't right

For a tree that's clearly hazardous—severe lean with root heaving, major cracks, or significant decay over a house—don't wait. This is urgent.

For trees you're uncertain about, an evaluation from a certified arborist provides peace of mind and expert guidance. The cost of an assessment is trivial compared to the cost of a tree hitting your house—or worse.

What Professionals Look For

A qualified arborist assesses risk more thoroughly:

• Sounding the trunk and major branches for hidden decay
• Evaluating root zone and soil conditions
• Assessing the whole tree systematically
• Considering species-specific failure patterns
• Using diagnostic tools when warranted

They can also advise on options: removal, pruning to reduce weight, cabling to support weak unions, or monitoring over time.

After Your Assessment

If You Found Concerns

Don't ignore them. Get a professional opinion, especially for trees near structures or high-use areas. Document what you've observed with photos in case you need them for insurance or future reference.

If Everything Looks OK

Great—but reassess periodically. Check trees after storms. Notice changes over time. Healthy trees can develop problems, and old damage can progress.

General Risk Reduction

Even for healthy trees, you can reduce risk:

• Remove dead branches (especially large ones over targets)
• Keep trees properly pruned to reduce wind resistance
• Maintain tree health through proper watering and care
• Consider removing high-risk trees proactively rather than waiting for failure

The Bottom Line

You don't need to be paranoid about your trees, but you should be aware. Most trees are fine most of the time. But failures do happen, and the consequences can be serious.

Learn to notice the warning signs. Pay attention to changes. Get professional help when you're uncertain. A little awareness goes a long way toward preventing tree-related disasters.