Deadwood Can Lead To Fallen Branches
Deadwood reduces the structural integrity of your tree and increases the chances of branches falling during winds and strong weather. Falling branches can cause significant damage to your home and injury to its occupants. This is most likely to happen during storm season, leaving parts of your home open to the elements at the worst time until you can have it repaired.
Deadwood Promotes Rot
Another downside to deadwood is the fact it becomes a home to all manner of pests that prefer to make their home there. Pests can introduce diseases and fungi which can cause the wood to rot. Further spreading damage in the tree and others nearby.
Maintaining the health of your trees is vital. Over time an unchecked infection becomes more difficult to treat, to the point where the whole tree must be removed. This is a much more extensive and expensive process.
Regulation Requires It Be Removed
Depending on your location it can actually be required by regulation to remove deadwood. Many schools and government bodies require dead branches that are 30mm or greater in diameter to be removed in order to preserve public safety.