Hollow Oak Tree: Assessing Safety and Longevity

A 36-inch diameter backyard oak is completely hollow—tape measure extends 23 inches inside. It leafs out well but owner fears it falling on neighbor's house.

Heart Rot ≠ Hazard

Hollow trees can stand decades. Safety depends on:

• Sound wood thickness: 36-inch oak needs ≥5.5 inches of solid wood outside the hollow.
• Growth rate: good growth = thicker sapwood = safer.
• Callus formation: healthy callus at wounds indicates vigor.
• Crown condition: full, green foliage is positive.
• Lean: upright trees are lower risk.

Oaks Are Low-Hazard

Even with 70% internal wood loss, heart rot alone rarely causes failure if no other defects exist.

Next Steps

• If crown is healthy and tree upright, likely safe.
• Hire a Certified Arborist or state Urban Forester for professional assessment.
• Large limbs typically fail before whole tree falls.

Don't rush removal; get expert evaluation first.