1. Old and overgrown branches might fall and injure people.
2. They may cause damage to electricity and telephone lines, houses, cars and other belongings.
3. Broken branches and leaves may create gutter.
4. Large root systems can cause damage to the foundation of your house.
5. Constant shade from the Sun will cause dampness on the roof.
To prevent all these problems you should trim and prune all trees and vegetation within 3 metres height standing near your house.