Cracks
Separation of wood fibres that appear in the bark. Cracks indicate failure has already ocurred. High to serious risk:
Cracks completely through stem or cracks in large branches. Cracks associated with other defects such as decay.

Decay
Cavities, or wood that has obvious physical and mechanical changes due to decay fungi.
High to serious risk:
t/R (t=Sound wood radius over R=stem radius less bark) is 0.3 or less in main stem or large branches.

Multiple attachments
Co-dominant main stems, or large scaffolds or branches joining to form weak unions.
High to serious risk:
Included bark present between unions; cracks, decay or excessive branch weight with included bark or v-crotches.

Root loss
Roots that provide structural support are decayed or have been cut or severed.
High to serious risk:
Root cutting over 40 per cent of root plate (functional roots supporting the tree). Soil heaving or cracking or root cracking indicating failure has started.

Deadwood
Dead branches will eventually fall
High to serious risk:
Large (greater than 10 cm) deadwood or broken lodged branches in a tree.